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proc(4)								       proc(4)

NAME
       proc - /proc, the process file system

       /proc  is  a  file  system  that	 provides  access to the state of each
       process and light-weight	process	(lwp) in the system. The name of  each
       entry  in  the  /proc  directory	is a decimal number corresponding to a
       process-ID. These entries are  themselves  subdirectories.   Access  to
       process	state  is  provided  by	additional files contained within each
       subdirectory; the hierarchy is described	more completely	below. In this
       document,  ``/proc file'' refers	to a non-directory file	within the hi-
       erarchy rooted at /proc.	The owner of each /proc	file and  subdirectory
       is determined by	the user-ID of the process.

       /proc  can  be  mounted on any mount point, in addition to the standard
       /proc mount point, and can be mounted several places at once. Such  ad-
       ditional	 mounts	 are allowed in	order to facilitate the	confinement of
       processes to subtrees of	the file system	via chroot(1M) and  yet	 allow
       such processes access to	commands like ps(1).

       Standard	 system	 calls	are  used  to  access  /proc  files:  open(2),
       close(2),  read(2),  and	 write(2)  (including	readv(2),   writev(2),
       pread(2),  and  pwrite(2)).  Most  files	describe process state and can
       only be opened for reading. ctl and lwpctl (control) files  permit  ma-
       nipulation of process state and can only	be opened for writing. as (ad-
       dress space) files contain the image of the running process and can  be
       opened for both reading and writing. An open for	writing	allows process
       control;	a read-only open allows	inspection but not  control.  In  this
       document, we refer to the process as open for reading or	writing	if any
       of its associated /proc files is	open for reading or writing.

       In general, more	than one process can open the same /proc file  at  the
       same  time.  Exclusive  open is an advisory mechanism provided to allow
       controlling processes to	avoid collisions with each  other.  A  process
       can obtain exclusive control of a target	process, with respect to other
       cooperating processes, if it successfully opens any /proc file  in  the
       target  process for writing (the	as or ctl files, or the	lwpctl file of
       any lwp)	while specifying O_EXCL	in the open(2).	Such an	open will fail
       if  the	target process is already open for writing (that is, if	an as,
       ctl, or lwpctl file is already open for writing). There can be any num-
       ber of concurrent read-only opens; O_EXCL is ignored on opens for read-
       ing. It is recommended that the first open for writing by a controlling
       process use the O_EXCL flag; multiple controlling processes usually re-
       sult in chaos.

       If a process opens one of its own /proc files  for  writing,  the  open
       succeeds	 regardless  of	 O_EXCL	 and  regardless of whether some other
       process has the process open for	writing. Self-opens do not count  when
       another process attempts	an exclusive open. (A process cannot exclude a
       debugger	by opening itself for writing and the application of a	debug-
       ger  cannot  prevent a process from opening itself.) All	self-opens for
       writing are forced to be	close-on-exec (see the	F_SETFD	 operation  of
       fcntl(2)).

       Data  may  be transferred from or to any	locations in the address space
       of the traced process by	applying lseek(2) to position the as  file  at
       the  virtual address of interest	followed by read(2) or write(2)	(or by
       using pread(2) or pwrite(2) for the combined operation).	 The  address-
       map  file  /proc/pid/map	 can be	read to	determine the accessible areas
       (mappings) of the address space.	I/O transfers may span contiguous map-
       pings.  An  I/O request extending into an unmapped area is truncated at
       the boundary. A write request beginning at an unmapped virtual  address
       fails with EIO; a read request beginning	at an unmapped virtual address
       returns zero (an	end-of-file indication).

       Information and control	operations  are	 provided  through  additional
       files.  <procfs.h>  contains definitions	of data	structures and message
       formats used with these files. Some of these  definitions  involve  the
       use  of	sets  of flags.	The set	types sigset_t,	fltset_t, and sysset_t
       correspond, respectively, to signal, fault, and	system	call  enumera-
       tions  defined  in  <sys/signal.h>, <sys/fault.h>, and <sys/syscall.h>.
       Each set	type is	large enough to	hold flags for	its  own  enumeration.
       Although	 they are of different sizes, they have	a common structure and
       can be manipulated by these macros:

       prfillset(&set);		    /* turn on all flags in set	*/
       premptyset(&set);	    /* turn off	all flags in set */
       praddset(&set, flag);	    /* turn on the specified flag */
       prdelset(&set, flag);	    /* turn off	the specified flag */
       r = prismember(&set, flag);  /* != 0 iff	flag is	turned on */

       One of prfillset() or premptyset() must be used to initialize  set  be-
       fore  it	 is  used in any other operation. flag must be a member	of the
       enumeration corresponding to set.

       Every process contains at least one light-weight	process, or lwp.  Each
       lwp  represents	a flow of execution that is independently scheduled by
       the operating system. All lwps in a process share its address space  as
       well as many other attributes.  Through the use of lwpctl and ctl files
       as described below, it is possible  to  affect  individual  lwps	 in  a
       process or to affect all	of them	at once, depending on the operation.

       When  the process has more than one lwp,	a representative lwp is	chosen
       by the system for certain process status	files and control  operations.
       The  representative  lwp	 is a stopped lwp only if all of the process's
       lwps are	stopped; is stopped on an event	of interest only if all	of the
       lwps are	so stopped (excluding PR_SUSPENDED lwps); is in	a PR_REQUESTED
       stop only if there are no other events of interest  to  be  found;  or,
       failing	everything  else, is in	a PR_SUSPENDED stop (implying that the
       process is deadlocked).	See the	description of	the  status  file  for
       definitions of stopped states. See the PCSTOP control operation for the
       definition of ``event of	interest''.

       The representative lwp remains fixed (it	will be	chosen	again  on  the
       next operation) as long as all of the lwps are stopped on events	of in-
       terest or are in	a PR_SUSPENDED stop and	the PCRUN control operation is
       not applied to any of them.

       When applied to the process control file, every /proc control operation
       that must act on	an lwp uses the	same algorithm to choose which lwp  to
       act  upon. Together with	synchronous stopping (see PCSET), this enables
       a debugger to control a multiple-lwp process using  only	 the  process-
       level status and	control	files if it so chooses.	More fine-grained con-
       trol can	be achieved using the lwp-specific files.

       The system supports two process data  models,  the  traditional	32-bit
       data  model in which ints, longs	and pointers are all 32	bits wide (the
       ILP32 data model), and on some platforms	the 64-bit data	model in which
       longs  and  pointers, but not ints, are 64 bits in width	(the LP64 data
       model). In the LP64 data	model some system data types, notably  size_t,
       off_t, time_t and dev_t,	grow from 32 bits to 64	bits as	well.

       The  /proc  interfaces  described here are available to both 32-bit and
       64-bit controlling processes. However, many operations attempted	 by  a
       32-bit  controlling  process  on	a 64-bit target	process	will fail with
       EOVERFLOW because the address space range of a  32-bit  process	cannot
       encompass  a  64-bit  process or	because	the data in some 64-bit	system
       data type cannot	be compressed to fit  into  the	 corresponding	32-bit
       type  without loss of information. Operations that fail in this circum-
       stance include reading and writing the address space, reading  the  ad-
       dress-map file, and setting the target process's	registers. There is no
       restriction on operations applied by  a	64-bit	process	 to  either  a
       32-bit or a 64-bit target processes.

       The  format of the contents of any /proc	file depends on	the data model
       of the observer (the controlling	process), not on the data model	of the
       target process. A 64-bit	debugger does not have to translate the	infor-
       mation it reads from a /proc file for a 32-bit process from 32-bit for-
       mat  to	64-bit format. However,	it usually has to be aware of the data
       model of	the target process. The	pr_dmodel field	of  the	 status	 files
       indicates the target process's data model.

       To help deal with system	data structures	that are read from 32-bit pro-
       cesses, a 64-bit	controlling program can	be compiled with  the  C  pre-
       processor  symbol _SYSCALL32 defined before system header files are in-
       cluded. This makes explicit 32-bit fixed-width  data  structures	 (like
       cstruct stat32) visible to the 64-bit program. See types32.h(3HEAD).

DIRECTORY STRUCTURE
       At  the	top  level, the	directory /proc	contains entries each of which
       names an	existing process in the	system.	These entries  are  themselves
       directories.  Except  where  otherwise noted, the files described below
       can be opened for reading only. In addition, if	a  process  becomes  a
       zombie  (one  that  has exited but whose	parent has not yet performed a
       wait(3C)	upon it), most of its associated /proc	files  disappear  from
       the  hierarchy;	subsequent  attempts to	open them, or to read or write
       files opened before the process exited, will elicit the error ENOENT.

       Although	process	state and consequently the contents of /proc files can
       change  from  instant  to  instant, a single read(2) of a /proc file is
       guaranteed to return a sane representation of state; that is, the  read
       will  be	atomic with respect to the state of the	process. No such guar-
       antee applies to	successive reads applied to a /proc file for a running
       process.	 In  addition,	atomicity is not guaranteed for	I/O applied to
       the as (address-space) file for a running  process  or  for  a  process
       whose address space contains memory shared by another running process.

       A number	of structure definitions are used to describe the files. These
       structures may grow by the addition of elements at the  end  in	future
       releases	of the system and it is	not legitimate for a program to	assume
       that they will not.

STRUCTURE OF /proc/pid
       A given directory /proc/pid contains the	following entries.  A  process
       can  use	the invisible alias /proc/self if it wishes to open one	of its
       own /proc files (invisible in the sense that the	name ``self'' does not
       appear  in  a  directory	 listing  of  /proc  obtained from ls(1), get-
       dents(2), or readdir(3C)).

   contracts
       A directory containing references to the	contracts held by the process.
       Each  entry is a	symlink	to the contract's directory under /system/con-
       tract. See contract(4).

   as
       Contains	the address-space image	of the process;	it can be  opened  for
       both  reading and writing. lseek(2) is used to position the file	at the
       virtual address of interest and then the	address	space can be  examined
       or  changed  through  read(2)  or  write(2)  (or	 by  using pread(2) or
       pwrite(2) for the combined operation).

   ctl
       A write-only file to which structured messages  are  written  directing
       the  system to change some aspect of the	process's state	or control its
       behavior	in some	way. The seek offset is	not relevant when  writing  to
       this file. Individual lwps also have associated lwpctl files in the lwp
       subdirectories.	A  control  message  may  be  written  either  to  the
       process's ctl file or to	a specific lwpctl file with operation-specific
       effects.	The effect of a	control	message	is  immediately	 reflected  in
       the  state of the process visible through appropriate status and	infor-
       mation files. The types of control messages  are	 described  in	detail
       later. See CONTROL MESSAGES.

   status
       Contains	 state	information  about  the	process	and the	representative
       lwp. The	file contains a	pstatus	structure which	contains  an  embedded
       lwpstatus structure for the representative lwp, as follows:

       typedef struct pstatus {
	    int	pr_flags;	      /* flags (see below) */
	    int	pr_nlwp;	      /* number	of active lwps in the process */
	    int	pr_nzomb;	      /* number	of zombie lwps in the process */
	    pid_tpr_pid;	      /* process id */
	    pid_tpr_ppid;	      /* parent	process	id */
	    pid_tpr_pgid;	      /* process group id */
	    pid_tpr_sid;	      /* session id */
	    id_t pr_aslwpid;	      /* obsolete */
	    id_t pr_agentid;	      /* lwp-id	of the agent lwp, if any */
	    sigset_t pr_sigpend;      /* set of	process	pending	signals	*/
	    uintptr_t pr_brkbase;     /* virtual address of the	process	heap */
	    size_t pr_brksize;	      /* size of the process heap, in bytes */
	    uintptr_t pr_stkbase;     /* virtual address of the	process	stack */
	    size_tpr_stksize;	      /* size of the process stack, in bytes */
	    timestruc_t	pr_utime;     /* process user cpu time */
	    timestruc_t	pr_stime;     /* process system	cpu time */
	    timestruc_t	pr_cutime;    /* sum of	children's user	times */
	    timestruc_t	pr_cstime;    /* sum of	children's system times	*/
	    sigset_t pr_sigtrace;     /* set of	traced signals */
	    fltset_t pr_flttrace;     /* set of	traced faults */
	    sysset_t pr_sysentry;     /* set of	system calls traced on entry */
	    sysset_t pr_sysexit;      /* set of	system calls traced on exit */
	    char pr_dmodel;	      /* data model of the process */
	    taskid_t pr_taskid;	      /* task id */
	    projid_t pr_projid;	      /* project id */
	    zoneid_t pr_zoneid;	      /* zone id */
	    lwpstatus_t	pr_lwp;	      /* status	of the representative lwp */
       } pstatus_t;

       pr_flags	 is a bit-mask holding the following process flags. For	conve-
       nience, it also contains	the lwp	flags for the representative lwp,  de-
       scribed later.

       PR_ISSYS	       process is a system process (see	PCSTOP).

       PR_VFORKP       process is the parent of	a vforked child	(see PCWATCH).

       PR_FORK	       process has its inherit-on-fork mode set	(see PCSET).

       PR_RLC	       process has its run-on-last-close mode set (see PCSET).

       PR_KLC	       process	has  its  kill-on-last-close mode set (see PC-
		       SET).

       PR_ASYNC	       process has its asynchronous-stop mode set (see PCSET).

       PR_MSACCT       Set by default in all processes to  indicate  that  mi-
		       crostate	 accounting is enabled.	However, this flag has
		       been deprecated and  no	longer	has  any  effect.  Mi-
		       crostate	accounting may not be disabled;	however, it is
		       still possible to toggle	the flag.

       PR_MSFORK       Set by default in all processes to  indicate  that  mi-
		       crostate	 accounting will be enabled for	processes that
		       this parent forks(). However, this flag has been	depre-
		       cated  and  no longer has any effect. It	is possible to
		       toggle this flag; however, it is	not possible  to  dis-
		       able microstate accounting.

       PR_BPTADJ       process has its breakpoint adjustment mode set (see PC-
		       SET).

       PR_PTRACE       process has its ptrace-compatibility mode set (see  PC-
		       SET).

       pr_nlwp	is the total number of active lwps in the process. pr_nzomb is
       the total number	of zombie lwps in the process. A zombie	lwp is a  non-
       detached	 lwp  that  has	 terminated  but  has  not  been  reaped  with
       thr_join(3C) or pthread_join(3C).

       pr_pid, pr_ppid,	pr_pgid, and pr_sid are, respectively, the process ID,
       the ID of the process's parent, the process's process group ID, and the
       process's session ID.

       pr_aslwpid is obsolete and is always zero.

       pr_agentid is the lwp-ID	for the	/proc agent lwp	(see the PCAGENT  con-
       trol operation).	It is zero if there is no agent	lwp in the process.

       pr_sigpend identifies asynchronous signals pending for the process.

       pr_brkbase is the virtual address of the	process	heap and pr_brksize is
       its size	in bytes. The address formed by	the sum	of these values	is the
       process	break  (see  brk(2)).  pr_stkbase  and pr_stksize are, respec-
       tively, the virtual address of the process stack	and its	size in	bytes.
       (Each  lwp  runs	on a separate stack; the distinguishing	characteristic
       of the process stack is that the	operating system  will	grow  it  when
       necessary.)

       pr_utime,  pr_stime,  pr_cutime,	 and  pr_cstime	are, respectively, the
       user CPU	and system CPU time consumed by	the process, and  the  cumula-
       tive  user  CPU and system CPU time consumed by the process's children,
       in seconds and nanoseconds.

       pr_sigtrace and pr_flttrace contain, respectively, the set  of  signals
       and  the	set of hardware	faults that are	being traced (see PCSTRACE and
       PCSFAULT).

       pr_sysentry and pr_sysexit contain, respectively, the  sets  of	system
       calls being traced on entry and exit (see PCSENTRY and PCSEXIT).

       pr_dmodel indicates the data model of the process. Possible values are:

       PR_MODEL_ILP32	       process data model is ILP32.

       PR_MODEL_LP64	       process data model is LP64.

       PR_MODEL_NATIVE	       process data model is native.

       The  pr_taskid,	pr_projid,  and	pr_zoneid fields contain respectively,
       the numeric IDs of the task, project, and zone in which the process was
       running.

       The constant PR_MODEL_NATIVE reflects the data model of the controlling
       process,	that is, its value is PR_MODEL_ILP32 or	PR_MODEL_LP64  accord-
       ing  to	whether	 the controlling process has been compiled as a	32-bit
       program or a 64-bit program, respectively.

       pr_lwp contains the status information for the representative lwp:

       typedef struct lwpstatus	{
	   int pr_flags;	       /* flags	(see below) */
	   id_t	pr_lwpid;	       /* specific lwp identifier */
	   short pr_why;	       /* reason for lwp stop, if stopped */
	   short pr_what;	       /* more detailed	reason */
	   short pr_cursig;	       /* current signal, if any */
	   siginfo_t pr_info;	       /* info associated with signal or fault */
	   sigset_t pr_lwppend;	       /* set of signals pending to the	lwp */
	   sigset_t pr_lwphold;	       /* set of signals blocked by the	lwp */
	   struct sigaction pr_action; /* signal action	for current signal */
	   stack_t pr_altstack;	       /* alternate signal stack info */
	   uintptr_t pr_oldcontext;    /* address of previous ucontext */
	   short pr_syscall;	       /* system call number (if in syscall) */
	   short pr_nsysarg;	       /* number of arguments to this syscall */
	   int pr_errno;	       /* errno	for failed syscall */
	   long	pr_sysarg[PRSYSARGS];  /* arguments to this syscall */
	   long	pr_rval1;	       /* primary syscall return value */
	   long	pr_rval2;	       /* second syscall return	value, if any */
	   char	pr_clname[PRCLSZ];     /* scheduling class name	*/
	   timestruc_t pr_tstamp;      /* real-time time stamp of stop */
	   timestruc_t pr_utime;       /* lwp user cpu time */
	   timestruc_t pr_stime;       /* lwp system cpu time */
	   uintptr_t pr_ustack;	       /* stack	boundary data (stack_t)	address	*/
	   ulong_t pr_instr;	       /* current instruction */
	   prgregset_t pr_reg;	       /* general registers */
	   prfpregset_t	pr_fpreg;      /* floating-point registers */
       } lwpstatus_t;

       pr_flags	is a bit-mask holding the  following  lwp  flags.  For	conve-
       nience, it also contains	the process flags, described previously.

       PR_STOPPED      The lwp is stopped.

       PR_ISTOP	       The  lwp	 is  stopped  on an event of interest (see PC-
		       STOP).

       PR_DSTOP	       The lwp has a stop directive in effect (see PCSTOP).

       PR_STEP	       The lwp has a  single-step  directive  in  effect  (see
		       PCRUN).

       PR_ASLEEP       The  lwp	 is  in	an interruptible sleep within a	system
		       call.

       PR_PCINVAL      The lwp's current instruction (pr_instr)	is undefined.

       PR_DETACH       This is a  detached  lwp	 (see  pthread_create(3C)  and
		       pthread_join(3C)).

       PR_DAEMON       This is a daemon	lwp (see pthread_create(3C)).

       PR_ASLWP	       This flag is obsolete and is never set.

       PR_AGENT	       This is the /proc agent lwp for the process.

       pr_lwpid	names the specific lwp.

       pr_why and pr_what together describe, for a stopped lwp,	the reason for
       the stop. Possible values of pr_why and the associated pr_what are:

       PR_REQUESTED    indicates that the stop occurred	in response to a  stop
		       directive,  normally  because PCSTOP was	applied	or be-
		       cause another lwp stopped on an event of	 interest  and
		       the  asynchronous-stop flag (see	PCSET) was not set for
		       the process. pr_what is unused in this case.

       PR_SIGNALLED    indicates that the lwp stopped on receipt of  a	signal
		       (see  PCSTRACE);	 pr_what  holds	the signal number that
		       caused the stop (for  a	newly-stopped  lwp,  the  same
		       value is	in pr_cursig).

       PR_FAULTED      indicates  that the lwp stopped on incurring a hardware
		       fault (see PCSFAULT); pr_what holds  the	 fault	number
		       that caused the stop.

       PR_SYSENTRY     indicate	 a stop	on entry to or exit from a system call
       PR_SYSEXIT      (see PCSENTRY and PCSEXIT); pr_what  holds  the	system
		       call number.

       PR_JOBCONTROL   indicates  that	the lwp	stopped	due to the default ac-
		       tion of a job control stop signal  (see	sigaction(2));
		       pr_what holds the stopping signal number.

       PR_SUSPENDED    indicates that the lwp stopped due to internal synchro-
		       nization	of lwps	within the process. pr_what is	unused
		       in this case.

       pr_cursig  names	the current signal, that is, the next signal to	be de-
       livered to the lwp, if any. pr_info, when the lwp is in a  PR_SIGNALLED
       or  PR_FAULTED  stop,  contains additional information pertinent	to the
       particular signal or fault (see <sys/siginfo.h>).

       pr_lwppend identifies any synchronous or	directed signals  pending  for
       the  lwp.  pr_lwphold  identifies those signals whose delivery is being
       blocked by the lwp (the signal mask).

       pr_action contains the signal action information	pertaining to the cur-
       rent  signal  (see sigaction(2)); it is undefined if pr_cursig is zero.
       pr_altstack contains the	alternate signal stack information for the lwp
       (see sigaltstack(2)).

       pr_oldcontext,  if not zero, contains the address on the	lwp stack of a
       ucontext	structure describing  the  previous  user-level	 context  (see
       ucontext.h(3HEAD)).  It is non-zero only	if the lwp is executing	in the
       context of a signal handler.

       pr_syscall is the number	of the system call, if any, being executed  by
       the  lwp; it is non-zero	if and only if the lwp is stopped on PR_SYSEN-
       TRY or PR_SYSEXIT, or is	asleep within a	system	call  (	 PR_ASLEEP  is
       set).  If pr_syscall is non-zero, pr_nsysarg is the number of arguments
       to the system call and pr_sysarg	contains the actual arguments.

       pr_rval1, pr_rval2, and pr_errno	are defined only if the	lwp is stopped
       on  PR_SYSEXIT  or  if  the PR_VFORKP flag is set. If pr_errno is zero,
       pr_rval1	and pr_rval2 contain the return	values from the	 system	 call.
       Otherwise,  pr_errno  contains  the error number	for the	failing	system
       call (see <sys/errno.h>).

       pr_clname contains the name of the lwp's	scheduling class.

       pr_tstamp, if the lwp is	stopped, contains a time  stamp	 marking  when
       the  lwp	 stopped,  in real time	seconds	and nanoseconds	since an arbi-
       trary time in the past.

       pr_utime	is the amount of user level CPU	time used by this LWP.

       pr_stime	is the amount of system	level CPU time used by this LWP.

       pr_ustack is the	virtual	address	of the stack_t that contains the stack
       boundaries for this LWP.	See getustack(2) and _stack_grow(3C).

       pr_instr	 contains  the	machine	instruction to which the lwp's program
       counter refers. The amount of data retrieved from the  process  is  ma-
       chine-dependent.	 On  SPARC  based  machines,  it  is a 32-bit word. On
       -based machines,	it is a	single byte. In	general, the size is  that  of
       the  machine's  smallest	instruction. If	PR_PCINVAL is set, pr_instr is
       undefined; this occurs whenever the lwp is not stopped or when the pro-
       gram counter refers to an invalid virtual address.

       pr_reg is an array holding the contents of a stopped lwp's general reg-
       isters.

       SPARC

	   On SPARC-based machines, the	predefined constants  R_G0  ...	 R_G7,
	   R_O0	 ...  R_O7, R_L0 ... R_L7, R_I0	... R_I7, R_PC,	R_nPC, and R_Y
	   can be used as indices to refer  to	the  corresponding  registers;
	   previous register windows can be read from their overflow locations
	   on  the  stack   (however,	see   the   gwindows   file   in   the
	   /proc/pid/lwp/lwpid subdirectory).

       SPARC V8	(32-bit)

	   For	SPARC  V8  (32-bit) controlling	processes, the predefined con-
	   stants R_PSR, R_WIM,	and R_TBR can be used as indices to  refer  to
	   the	corresponding  special	registers.  For	SPARC V9 (64-bit) con-
	   trolling processes, the  predefined	constants  R_CCR,  R_ASI,  and
	   R_FPRS can be used as indices to refer to the corresponding special
	   registers.

	(32-bit)

	   For 32-bit  processes, the predefined constants listed belowcan  be
	   used	as indices to refer to the corresponding registers.

	   SS
	   UESP
	   EFL
	   CS
	   EIP
	   ERR
	   TRAPNO
	   EAX
	   ECX
	   EDX
	   EBX
	   ESP
	   EBP
	   ESI
	   EDI
	   DS
	   ES
	   GS

	   The preceding constants are listed in <sys/regset.h>.

	   Note	 that a	32-bit process can run on an  64-bit system, using the
	   constants listed above.

	(64-bit)

	   To read the registers of a  32-  or	a  64-bit  process,  a	64-bit
	   process should use the predefined constants listed below.

	   REG_GSBASE
	   REG_FSBASE
	   REG_DS
	   REG_ES
	   REG_GS
	   REG_FS
	   REG_SS
	   REG_RSP
	   REG_RFL
	   REG_CS
	   REG_RIP
	   REG_ERR
	   REG_TRAPNO
	   REG_RAX
	   REG_RCX
	   REG_RDX
	   REG_RBX
	   REG_RBP
	   REG_RSI
	   REG_RDI
	   REG_R8
	   REG_R9
	   REG_R10
	   REG_R11
	   REG_R12
	   REG_R13
	   REG_R14
	   REG_R15

	   The preceding constants are listed in <sys/regset.h>.

       pr_fpreg	is a structure holding the contents of the floating-point reg-
       isters.

       SPARC registers,	both general and floating-point, as seen by  a	64-bit
       controlling  process  are the V9	versions of the	registers, even	if the
       target process is a 32-bit (V8) process.	V8 registers are a  subset  of
       the V9 registers.

       If the lwp is not stopped, all register values are undefined.

   psinfo
       Contains	 miscellaneous information about the process and the represen-
       tative lwp needed by the	ps(1) command. psinfo remains accessible after
       a  process becomes a zombie. The	file contains a	psinfo structure which
       contains	an embedded lwpsinfo structure for the representative lwp,  as
       follows:

       typedef struct psinfo {
	   int pr_flag;		     /*	process	flags (DEPRECATED: see below) */
	   int pr_nlwp;		     /*	number of active lwps in the process */
	   int pr_nzomb;	     /*	number of zombie lwps in the process */
	   pid_t pr_pid;	     /*	process	id */
	   pid_t pr_ppid;	     /*	process	id of parent */
	   pid_t pr_pgid;	     /*	process	id of process group leader */
	   pid_t pr_sid;	     /*	session	id */
	   uid_t pr_uid;	     /*	real user id */
	   uid_t pr_euid;	     /*	effective user id */
	   gid_t pr_gid;	     /*	real group id */
	   gid_t pr_egid;	     /*	effective group	id */
	   uintptr_t pr_addr;	     /*	address	of process */
	   size_t pr_size;	     /*	size of	process	image in Kbytes	*/
	   size_t pr_rssize;	     /*	resident set size in Kbytes */
	   dev_t pr_ttydev;	     /*	controlling tty	device (or PRNODEV) */
	   ushort_t pr_pctcpu;	     /*	% of recent cpu	time used by all lwps */
	   ushort_t pr_pctmem;	     /*	% of system memory used	by process */
	   timestruc_t pr_start;     /*	process	start time, from the epoch */
	   timestruc_t pr_time;	     /*	cpu time for this process */
	   timestruc_t pr_ctime;     /*	cpu time for reaped children */
	   char	pr_fname[PRFNSZ];    /*	name of	exec'ed	file */
	   char	pr_psargs[PRARGSZ];  /*	initial	characters of arg list */
	   int pr_wstat;	     /*	if zombie, the wait() status */
	   int pr_argc;		     /*	initial	argument count */
	   uintptr_t pr_argv;	     /*	address	of initial argument vector */
	   uintptr_t pr_envp;	     /*	address	of initial environment vector */
	   char	pr_dmodel;	     /*	data model of the process */
	   lwpsinfo_t pr_lwp;	     /*	information for	representative lwp */
	   taskid_t pr_taskid;	     /*	task id	*/
	   projid_t pr_projid;	     /*	project	id */
	   poolid_t pr_poolid;	     /*	pool id	*/
	   zoneid_t pr_zoneid;	     /*	zone id	*/
	   ctid_t pr_contract;	     /*	process	contract id */
       } psinfo_t;

       Some  of	the entries in psinfo, such as pr_addr,	refer to internal ker-
       nel data	structures and should not be expected to retain	their meanings
       across different	versions of the	operating system.

       psinfo_t.pr_flag	 is  a	deprecated  interface that should no longer be
       used. Applications currently relying on the SSYS	bit in pr_flag	should
       migrate to checking PR_ISSYS in the pstatus structure's pr_flags	field.

       pr_pctcpu and pr_pctmem are 16-bit binary fractions in the range	0.0 to
       1.0 with	the binary point to the	right of the high-order	 bit  (1.0  ==
       0x8000).	pr_pctcpu is the summation over	all lwps in the	process.

       pr_lwp  contains	 the  ps(1) information	for the	representative lwp. If
       the process is a	zombie,	pr_nlwp,  pr_nzomb,  and  pr_lwp.pr_lwpid  are
       zero and	the other fields of pr_lwp are undefined:

       typedef struct lwpsinfo {
	   int pr_flag;		     /*	lwp flags (DEPRECATED: see below) */
	   id_t	pr_lwpid;	     /*	lwp id */
	   uintptr_t pr_addr;	     /*	internal address of lwp	*/
	   uintptr_t pr_wchan;	     /*	wait addr for sleeping lwp */
	   char	pr_stype;	     /*	synchronization	event type */
	   char	pr_state;	     /*	numeric	lwp state */
	   char	pr_sname;	     /*	printable character for	pr_state */
	   char	pr_nice;	     /*	nice for cpu usage */
	   short pr_syscall;	     /*	system call number (if in syscall) */
	   char	pr_oldpri;	     /*	pre-SVR4, low value is high priority */
	   char	pr_cpu;		     /*	pre-SVR4, cpu usage for	scheduling */
	   int pr_pri;		     /*	priority, high value = high priority */
	   ushort_t pr_pctcpu;	     /*	% of recent cpu	time used by this lwp */
	   timestruc_t pr_start;     /*	lwp start time,	from the epoch */
	   timestruc_t pr_time;	     /*	cpu time for this lwp */
	   char	pr_clname[PRCLSZ];   /*	scheduling class name */
	   char	pr_name[PRFNSZ];     /*	name of	system lwp */
	   processorid_t pr_onpro;   /*	processor which	last ran this lwp */
	   processorid_t pr_bindpro; /*	processor to which lwp is bound	*/
	   psetid_t pr_bindpset;     /*	processor set to which lwp is bound */
       } lwpsinfo_t;

       Some  of	 the entries in	lwpsinfo, such as pr_addr, pr_wchan, pr_stype,
       pr_state, and pr_name, refer to internal	 kernel	 data  structures  and
       should  not  be expected	to retain their	meanings across	different ver-
       sions of	the operating system.

       lwpsinfo_t.pr_flag is a deprecated interface that should	no  longer  be
       used.

       pr_pctcpu  is  a	 16-bit	binary fraction, as described above. It	repre-
       sents the CPU time used by the specific lwp. On a  multi-processor  ma-
       chine, the maximum value	is 1/N,	where N	is the number of CPUs.

       pr_contract is the id of	the process contract of	which the process is a
       member. See contract(4) and process(4).

   cred
       Contains	a description of the credentials associated with the process:

       typedef struct prcred {
	    uid_t pr_euid;	/* effective user id */
	    uid_t pr_ruid;	/* real	user id	*/
	    uid_t pr_suid;	/* saved user id (from exec) */
	    gid_t pr_egid;	/* effective group id */
	    gid_t pr_rgid;	/* real	group id */
	    gid_t pr_sgid;	/* saved group id (from	exec) */
	    int	pr_ngroups;	/* number of supplementary groups */
	    gid_t pr_groups[1];	/* array of supplementary groups */
       } prcred_t;

       The array of associated supplementary groups in pr_groups is  of	 vari-
       able  length;  the  cred	file contains all of the supplementary groups.
       pr_ngroups indicates the	number of supplementary	groups.	(See also  the
       PCSCRED and PCSCREDX control operations.)

   priv
       Contains	a description of the privileges	associated with	the process:

       typedef struct prpriv {
	    uint32_t	    pr_nsets;	   /* number of	privilege set */
	    uint32_t	    pr_setsize;	   /* size of privilege	set */
	    uint32_t	    pr_infosize;   /* size of supplementary data */
	    priv_chunk_t    pr_sets[1];	   /* array of sets */
       } prpriv_t;

       The actual dimension of the pr_sets[] field is

       pr_sets[pr_nsets][pr_setsize]

       which  is  followed  by	additional information about the process state
       pr_infosize bytes in size.

       The   full   size   of	the   structure	  can	be   computed	 using
       PRIV_PRPRIV_SIZE(prpriv_t *).

   sigact
       Contains	an array of sigaction structures describing the	current	dispo-
       sitions of all signals associated with the traced process  (see	sigac-
       tion(2)).   Signal  numbers  are	 displaced by 1	from array indices, so
       that the	action for signal number n appears in position n-1 of the  ar-
       ray.

   auxv
       Contains	 the initial values of the process's aux vector	in an array of
       auxv_t structures (see <sys/auxv.h>). The values	are  those  that  were
       passed  by  the	operating system as startup information	to the dynamic
       linker.

   ldt
       This file exists	only on	-based machines. It is non-empty only  if  the
       process	has  established a local descriptor table (LDT). If non-empty,
       the file	contains the array of currently	active LDT entries in an array
       of  elements of type struct ssd,	defined	in <sys/sysi86.h>, one element
       for each	active LDT entry.

   map
       Contains	information about the virtual address map of the process.  The
       file  contains  an array	of prmap structures, each of which describes a
       contiguous virtual address region in the	address	space  of  the	traced
       process:

       typedef struct prmap {
	    uintptr_tpr_vaddr;	       /* virtual address of mapping */
	    size_t pr_size;	       /* size of mapping in bytes */
	    char pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	    offset_t pr_offset;	       /* offset into mapped object, if	any */
	    int	pr_mflags;	       /* protection and attribute flags */
	    int	pr_pagesize;	       /* pagesize for this mapping in bytes */
	    int	pr_shmid;	       /* SysV shared memory identifier	*/
       } prmap_t;

       pr_vaddr	 is  the  virtual  address  of	the  mapping within the	traced
       process and pr_size is its size in bytes. pr_mapname, if	 it  does  not
       contain a null string, contains the name	of a file in the object	direc-
       tory (see below)	that can be opened read-only to	obtain a file descrip-
       tor for the mapped file associated with the mapping. This enables a de-
       bugger to find object file symbol tables	without	 having	 to  know  the
       real  path  names  of  the  executable file and shared libraries	of the
       process.	pr_offset is the 64-bit	offset within the mapped file (if any)
       to which	the virtual address is mapped.

       pr_mflags is a bit-mask of protection and attribute flags:

       MA_READ	       mapping is readable by the traced process.

       MA_WRITE	       mapping is writable by the traced process.

       MA_EXEC	       mapping is executable by	the traced process.

       MA_SHARED       mapping changes are shared by the mapped	object.

       MA_ISM	       mapping	is  intimate  shared  memory  (shared  MMU re-
		       sources)

       MAP_NORESERVE   mapping does not	have swap space	reserved (mapped  with
		       MAP_NORESERVE)

       MA_SHM	       mapping System V	shared memory

       A  contiguous  area  of	the  address  space having the same underlying
       mapped object may appear	as multiple  mappings  due  to	varying	 read,
       write,  and  execute  attributes. The underlying	mapped object does not
       change over the range of	a single mapping. An I/O operation to  a  map-
       ping  marked MA_SHARED fails if applied at a virtual address not	corre-
       sponding	to a valid page	in the underlying mapped object. A write to  a
       MA_SHARED  mapping  that	is not marked MA_WRITE fails. Reads and	writes
       to private mappings always succeed. Reads and writes  to	 unmapped  ad-
       dresses fail.

       pr_pagesize is the page size for	the mapping, currently always the sys-
       tem pagesize.

       pr_shmid	is the shared memory identifier, if any, for the mapping.  Its
       value  is  -1  if  the  mapping	is  not	 System	 V  shared memory. See
       shmget(2).

   rmap
       Contains	information about the reserved address ranges of the  process.
       The  file  contains  an array of	prmap structures, as defined above for
       the map file. Each structure describes a	contiguous virtual address re-
       gion in the address space of the	traced process that is reserved	by the
       system in the sense that	an mmap(2) system call that does  not  specify
       MAP_FIXED  will not use any part	of it for the new mapping. Examples of
       such reservations include the address ranges reserved for  the  process
       stack and the individual	thread stacks of a multi-threaded process.

   cwd
       A  symbolic  link  to  the  process's  current  working	directory. See
       chdir(2). A readlink(2) of /proc/pid/cwd	yields a null string. However,
       it  can	be opened, listed, and searched	as a directory,	and can	be the
       target of chdir(2).

   root
       A symbolic link to the process's	 root  directory.  /proc/pid/root  can
       differ  from the	system root directory if the process or	one of its an-
       cestors executed	chroot(2) as super user. It has	the same semantics  as
       /proc/pid/cwd.

   fd
       A  directory  containing	 references  to	the open files of the process.
       Each entry is a decimal number corresponding to an open file descriptor
       in the process.

       If an entry refers to a regular file, it	can be opened with normal file
       system semantics	but, to	ensure that  the  controlling  process	cannot
       gain  greater  access  than the controlled process, with	no file	access
       modes other than	its read/write open modes in the  controlled  process.
       If an entry refers to a directory, it can be accessed with the same se-
       mantics as /proc/pid/cwd. An attempt to open any	other  type  of	 entry
       fails with EACCES.

   object
       A  directory containing read-only files with names corresponding	to the
       pr_mapname entries in the map and pagedata files. Opening such  a  file
       yields a	file descriptor	for the	underlying mapped file associated with
       an address-space	mapping	in the process.	The file name a.out appears in
       the directory as	an alias for the process's executable file.

       The  object  directory  makes  it possible for a	controlling process to
       gain access to the object file and any  shared  libraries  (and	conse-
       quently the symbol tables) without having to know the actual path names
       of the executable files.

   path
       A directory containing symbolic links to	files opened by	 the  process.
       The  directory  includes	one entry for cwd and root. The	directory also
       contains	a numerical entry for each file	descriptor in  the  fd	direc-
       tory,  and  entries matching those in the object	directory. If this in-
       formation is not	avilable, any attempt to read the contents of the sym-
       bolic  link  will fail. This is most common for files that do not exist
       in the filesystem namespace (such as FIFOs and sockets),	but  can  also
       happen for regular files. For the file descriptor entries, the path may
       be different from the one used by the process to	open the file.

   pagedata
       Opening the page	data file enables tracking of address space references
       and modifications on a per-page basis.

       A read(2) of the	page data file descriptor returns structured page data
       and atomically clears the page data maintained for the file by the sys-
       tem.  That  is  to say, each read returns data collected	since the last
       read; the first read returns data collected since the file was  opened.
       When  the call completes, the read buffer contains the following	struc-
       ture as its header and thereafter contains a number of  section	header
       structures  and associated byte arrays that must	be accessed by walking
       linearly	through	the buffer.

       typedef struct prpageheader {
	   timestruc_t pr_tstamp; /* real time stamp, time of read() */
	   ulong_t pr_nmap;	  /* number of address space mappings */
	   ulong_t pr_npage;	  /* total number of pages */
       } prpageheader_t;

       The header is followed by pr_nmap  prasmap  structures  and  associated
       data arrays. The	prasmap	structure contains the following elements:

       typedef struct prasmap {
	   uintptr_t pr_vaddr;	      /* virtual address of mapping */
	   ulong_t pr_npage;	      /* number	of pages in mapping */
	   char	pr_mapname[PRMAPSZ];  /* name in /proc/pid/object */
	   offset_t pr_offset;	      /* offset	into mapped object, if any */
	   int pr_mflags;	      /* protection and	attribute flags	*/
	   int pr_pagesize;	      /* pagesize for this mapping in bytes */
	   int pr_shmid;	      /* SysV shared memory identifier */
       } prasmap_t;

       Each  section  header  is followed by pr_npage bytes, one byte for each
       page in the mapping, plus 0-7 null bytes	at the end so  that  the  next
       prasmap	structure  begins on an	eight-byte aligned boundary. Each data
       byte may	contain	these flags:

       PG_REFERENCED	       page has	been referenced.

       PG_MODIFIED	       page has	been modified.

       If the read buffer is not large enough to contain all of	the page data,
       the  read  fails	 with  E2BIG and the page data is not cleared. The re-
       quired size of the read buffer can be determined	through	fstat(2).  Ap-
       plication  of lseek(2) to the page data file descriptor is ineffective;
       every read starts from the beginning of the file. Closing the page data
       file descriptor terminates the system overhead associated with collect-
       ing the data.

       More than one page data file descriptor for the	same  process  can  be
       opened,	up to a	system-imposed limit per traced	process. A read	of one
       does not	affect the data	being collected	by the system for the  others.
       An  open	 of the	page data file will fail with ENOMEM if	the system-im-
       posed limit would be exceeded.

   watch
       Contains	an array of prwatch structures,	one for	each watched area  es-
       tablished by the	PCWATCH	control	operation. See PCWATCH for details.

   usage
       Contains	 process  usage	 information  described	by a prusage structure
       which contains at least the following fields:

       typedef struct prusage {
	   id_t	pr_lwpid;	    /* lwp id.	0: process or defunct */
	   int pr_count;	    /* number of contributing lwps */
	   timestruc_t pr_tstamp;   /* real time stamp,	time of	read() */
	   timestruc_t pr_create;   /* process/lwp creation time stamp */
	   timestruc_t pr_term;	    /* process/lwp termination time stamp */
	   timestruc_t pr_rtime;    /* total lwp real (elapsed)	time */
	   timestruc_t pr_utime;    /* user level CPU time */
	   timestruc_t pr_stime;    /* system call CPU time */
	   timestruc_t pr_ttime;    /* other system trap CPU time */
	   timestruc_t pr_tftime;   /* text page fault sleep time */
	   timestruc_t pr_dftime;   /* data page fault sleep time */
	   timestruc_t pr_kftime;   /* kernel page fault sleep time */
	   timestruc_t pr_ltime;    /* user lock wait sleep time */
	   timestruc_t pr_slptime;  /* all other sleep time */
	   timestruc_t pr_wtime;    /* wait-cpu	(latency) time */
	   timestruc_t pr_stoptime; /* stopped time */
	   ulong_t pr_minf;	    /* minor page faults */
	   ulong_t pr_majf;	    /* major page faults */
	   ulong_t pr_nswap;	    /* swaps */
	   ulong_t pr_inblk;	    /* input blocks */
	   ulong_t pr_oublk;	    /* output blocks */
	   ulong_t pr_msnd;	    /* messages	sent */
	   ulong_t pr_mrcv;	    /* messages	received */
	   ulong_t pr_sigs;	    /* signals received	*/
	   ulong_t pr_vctx;	    /* voluntary context switches */
	   ulong_t pr_ictx;	    /* involuntary context switches */
	   ulong_t pr_sysc;	    /* system calls */
	   ulong_t pr_ioch;	    /* chars read and written */
       } prusage_t;

       Microstate accounting is	now continuously enabled. While	this  informa-
       tion  was previously an estimate, if microstate accounting were not en-
       abled, the current information is now never an estimate represents time
       the process has spent in	various	states.

   lstatus
       Contains	 a prheader structure followed by an array of lwpstatus	struc-
       tures,  one  for	 each  active	lwp   in   the	 process   (see	  also
       /proc/pid/lwp/lwpid/lwpstatus, below). The prheader structure describes
       the number and size of the array	entries	that follow.

       typedef struct prheader {
	   long	pr_nent;	/* number of entries */
	   size_t pr_entsize;	/* size	of each	entry, in bytes	*/
       } prheader_t;

       The lwpstatus structure may grow	by the addition	of elements at the end
       in  future  releases of the system. Programs must use pr_entsize	in the
       file header to index through the	array. These  comments	apply  to  all
       /proc  files that include a prheader structure (lpsinfo and lusage, be-
       low).

   lpsinfo
       Contains	a prheader structure followed by an array of  lwpsinfo	struc-
       tures,  one  for	 eachactive  and  zombie  lwp in the process. See also
       /proc/pid/lwp/lwpid/lwpsinfo, below.

   lusage
       Contains	a prheader structure followed by an array  of  prusage	struc-
       tures,  one for each active lwp in the process, plus an additional ele-
       ment at the beginning that contains the summation over all defunct lwps
       (lwps  that once	existed	but no longer exist in the process). Excluding
       the pr_lwpid, pr_tstamp,	pr_create, and pr_term entries,	the  entry-by-
       entry  summation	 over  all  these  structures is the definition	of the
       process usage information obtained  from	 the  usage  file.  (See  also
       /proc/pid/lwp/lwpid/lwpusage, below.)

   lwp
       A  directory containing entries each of which names an active or	zombie
       lwp within the process. These entries are themselves  directories  con-
       taining additional files	as described below. Only the lwpsinfo file ex-
       ists in the directory of	a zombie lwp.

STRUCTURE OF /proc/pid/lwp/ lwpid
       A given directory /proc/pid/lwp/lwpid contains the following entries:

   lwpctl
       Write-only control file.	The messages written to	this file  affect  the
       specific	lwp rather than	the representative lwp,	as is the case for the
       process's ctl file.

   lwpstatus
       lwp-specific state information. This file contains the lwpstatus	struc-
       ture for	the specific lwp as described above for	the representative lwp
       in the process's	status file.

   lwpsinfo
       lwp-specific ps(1) information. This file contains the lwpsinfo	struc-
       ture for	the specific lwp as described above for	the representative lwp
       in the process's	psinfo file. The lwpsinfo file remains accessible  af-
       ter an lwp becomes a zombie.

   lwpusage
       This  file  contains  the prusage structure for the specific lwp	as de-
       scribed above for the process's usage file.

   gwindows
       This file exists	only on	SPARC based machines. If it is	non-empty,  it
       contains	 a  gwindows_t	structure, defined in <sys/regset.h>, with the
       values of those SPARC register windows that could not be	stored on  the
       stack when the lwp stopped. Conditions under which register windows are
       not stored on the stack are: the	stack pointer  refers  to  nonexistent
       process	memory	or the stack pointer is	improperly aligned. If the lwp
       is not stopped or if there are no register windows that	could  not  be
       stored on the stack, the	file is	empty (the usual case).

   xregs
       Extra state registers. The extra	state register set is architecture de-
       pendent;	this file is empty if the system does not support extra	 state
       registers. If the file is non-empty, it contains	an architecture	depen-
       dent structure of type prxregset_t, defined  in	<procfs.h>,  with  the
       values  of  the lwp's extra state registers. If the lwp is not stopped,
       all register values are undefined. See also the PCSXREG control	opera-
       tion, below.

   asrs
       This  file  exists  only	 for 64-bit SPARC V9 processes.	It contains an
       asrset_t	structure, defined in <sys/regset.h>, containing the values of
       the  lwp's  platform-dependent ancillary	state registers. If the	lwp is
       not stopped, all	register values	are undefined. See  also  the  PCSASRS
       control operation, below.

   templates
       A  directory  which contains references to the active templates for the
       lwp, named by the contract type.	Changes	made to	an active template de-
       scriptor	 do  not  affect  the  original	 template which	was activated,
       though they do affect the active	template. It is	not possible to	 acti-
       vate an active template descriptor. See contract(4).

CONTROL	MESSAGES
       Process	state  changes	are  effected  through	messages  written to a
       process's ctl file or to	an individual lwp's lwpctl file.  All  control
       messages	 consist  of a long that names the specific operation followed
       by additional data containing the operand, if any.

       Multiple	control	messages may be	combined  in  a	 single	 write(2)  (or
       writev(2)) to a control file, but no partial writes are permitted. That
       is, each	control	message, operation code	plus operand, if any, must  be
       presented  in  its entirety to the write(2) and not in pieces over sev-
       eral system calls. If a control operation fails,	no  subsequent	opera-
       tions contained in the same write(2) are	attempted.

       Descriptions  of	 the  allowable	control	messages follow. In all	cases,
       writing a message to a control file for a process or lwp	that has  ter-
       minated elicits the error ENOENT.

   PCSTOP PCDSTOP PCWSTOP PCTWSTOP
       When  applied  to  the process control file, PCSTOP directs all lwps to
       stop and	waits for them to stop,	PCDSTOP	directs	all lwps to stop with-
       out  waiting for	them to	stop, and PCWSTOP simply waits for all lwps to
       stop. When applied to an	lwp control file, PCSTOP directs the  specific
       lwp  to	stop  and waits	until it has stopped, PCDSTOP directs the spe-
       cific lwp to stop without waiting for it	to stop,  and  PCWSTOP	simply
       waits  for  the	specific  lwp  to stop.	When applied to	an lwp control
       file, PCSTOP and	PCWSTOP	complete when the lwp stops on an event	of in-
       terest,	immediately if already so stopped; when	applied	to the process
       control file, they complete when	every lwp has  stopped	either	on  an
       event of	interest or on a PR_SUSPENDED stop.

       PCTWSTOP	 is  identical to PCWSTOP except that it enables the operation
       to time out, to avoid waiting forever for a process  or	lwp  that  may
       never stop on an	event of interest. PCTWSTOP takes a long operand spec-
       ifying a	number of milliseconds;	the wait will  terminate  successfully
       after  the  specified number of milliseconds even if the	process	or lwp
       has not stopped;	a timeout value	of zero	makes the operation  identical
       to PCWSTOP.

       An  ``event  of interest'' is either a PR_REQUESTED stop	or a stop that
       has been	specified in the process's tracing  flags  (set	 by  PCSTRACE,
       PCSFAULT,  PCSENTRY, and	PCSEXIT). PR_JOBCONTROL	and PR_SUSPENDED stops
       are specifically	not events of interest.	(An lwp	may stop twice due  to
       a  stop	signal,	first showing PR_SIGNALLED if the signal is traced and
       again showing PR_JOBCONTROL if the lwp is set running without  clearing
       the signal.) If PCSTOP or PCDSTOP is applied to an lwp that is stopped,
       but not on an event of interest,	the stop directive takes  effect  when
       the  lwp	is restarted by	the competing mechanism. At that time, the lwp
       enters a	PR_REQUESTED stop before executing any user-level code.

       A write of a control message that blocks	is interruptible by  a	signal
       so  that,  for example, an alarm(2) can be set to avoid waiting forever
       for a process or	lwp that may never stop	on an event  of	 interest.  If
       PCSTOP  is  interrupted,	 the lwp stop directives remain	in effect even
       though the write(2) returns an error. (Use of PCTWSTOP with a  non-zero
       timeout is recommended over PCWSTOP with	an alarm(2).)

       A  system  process  (indicated  by the PR_ISSYS flag) never executes at
       user level, has no user-level address space visible through /proc,  and
       cannot be stopped. Applying one of these	operations to a	system process
       or any of its lwps elicits the error EBUSY.

   PCRUN
       Make an lwp runnable again after	a stop.	This operation	takes  a  long
       operand containing zero or more of the following	flags:

       PRCSIG	       clears the current signal, if any (see PCCSIG).

       PRCFAULT	       clears the current fault, if any	(see PCCFAULT).

       PRSTEP	       directs	the  lwp  to execute a single machine instruc-
		       tion. On	completion of the instruction,	a  trace  trap
		       occurs.	If  FLTTRACE  is  being	traced,	the lwp	stops;
		       otherwise, it is	sent  SIGTRAP.	If  SIGTRAP  is	 being
		       traced  and is not blocked, the lwp stops. When the lwp
		       stops on	an event of interest, the  single-step	direc-
		       tive  is	 cancelled, even if the	stop occurs before the
		       instruction is executed.	This operation requires	 hard-
		       ware and	operating system support and may not be	imple-
		       mented on all processors. It is	implemented  on	 SPARC
		       and -based machines.

       PRSABORT	       is  meaningful only if the lwp is in a PR_SYSENTRY stop
		       or is marked PR_ASLEEP; it instructs the	lwp  to	 abort
		       execution  of  the  system  call	 (see PCSENTRY and PC-
		       SEXIT).

       PRSTOP	       directs the lwp to stop again as	soon as	possible after
		       resuming	execution (see PCDSTOP). In particular,	if the
		       lwp is stopped on PR_SIGNALLED or PR_FAULTED, the  next
		       stop  will  show	 PR_REQUESTED, no other	stop will have
		       intervened, and the lwp	will  not  have	 executed  any
		       user-level code.

       When  applied  to an lwp	control	file, PCRUN clears any outstanding di-
       rected-stop request and makes the specific lwp runnable.	The  operation
       fails  with EBUSY if the	specific lwp is	not stopped on an event	of in-
       terest or has not been directed to stop or if the agent lwp exists  and
       this is not the agent lwp (see PCAGENT).

       When  applied to	the process control file, a representative lwp is cho-
       sen for the operation as	described for /proc/pid/status.	The  operation
       fails  with  EBUSY if the representative	lwp is not stopped on an event
       of interest or has not been directed to stop or if the  agent  lwp  ex-
       ists. If	PRSTEP or PRSTOP was requested,	the representative lwp is made
       runnable	and its	outstanding directed-stop request is  cleared;	other-
       wise  all outstanding directed-stop requests are	cleared	and, if	it was
       stopped on an event of  interest,  the  representative  lwp  is	marked
       PR_REQUESTED. If, as a consequence, all lwps are	in the PR_REQUESTED or
       PR_SUSPENDED  stop  state,  all	lwps  showing  PR_REQUESTED  are  made
       runnable.

   PCSTRACE
       Define a	set of signals to be traced in the process. The	receipt	of one
       of these	signals	by an lwp causes the lwp to stop. The set  of  signals
       is  defined using an operand sigset_t contained in the control message.
       Receipt of SIGKILL cannot be traced; if specified, it is	 silently  ig-
       nored.

       If  a  signal  that is included in an lwp's held	signal set (the	signal
       mask) is	sent to	the lwp, the signal is not received and	does not cause
       a  stop until it	is removed from	the held signal	set, either by the lwp
       itself or by setting the	held signal set	with PCSHOLD.

   PCCSIG
       The current signal, if any, is cleared from the specific	or representa-
       tive lwp.

   PCSSIG
       The  current  signal and	its associated signal information for the spe-
       cific or	representative lwp are set according to	the  contents  of  the
       operand	siginfo	structure (see <sys/siginfo.h>). If the	specified sig-
       nal number is zero, the current signal is  cleared.  The	 semantics  of
       this  operation	are different from those of kill(2) in that the	signal
       is delivered to the lwp immediately after execution is resumed (even if
       it  is  being blocked) and an additional	PR_SIGNALLED stop does not in-
       tervene even if the signal is traced. Setting  the  current  signal  to
       SIGKILL terminates the process immediately.

   PCKILL
       If applied to the process control file, a signal	is sent	to the process
       with semantics identical	to those of kill(2). If	applied	to an lwp con-
       trol file, a directed signal is sent to the specific lwp. The signal is
       named in	a long operand contained in the	message. Sending SIGKILL  ter-
       minates the process immediately.

   PCUNKILL
       A  signal  is  deleted,	that is, it is removed from the	set of pending
       signals.	If applied to the process control file,	the signal is  deleted
       from  the process's pending signals. If applied to an lwp control file,
       the signal is deleted from the lwp's pending signals. The current  sig-
       nal  (if	 any)  is unaffected. The signal is named in a long operand in
       the control message. It is an  error  (EINVAL)  to  attempt  to	delete
       SIGKILL.

   PCSHOLD
       Set  the	 set  of  held	signals	for the	specific or representative lwp
       (signals	whose delivery will be blocked if sent to the lwp). The	set of
       signals	is specified with a sigset_t operand. SIGKILL and SIGSTOP can-
       not be held; if specified, they are silently ignored.

   PCSFAULT
       Define a	set of hardware	faults to be traced in the process. On	incur-
       ring  one of these faults, an lwp stops.	The set	is defined via the op-
       erand fltset_t structure. Fault names are defined in <sys/fault.h>  and
       include	the  following.	Some of	these may not occur on all processors;
       there may be processor-specific faults in addition to these.

       FLTILL	       illegal instruction

       FLTPRIV	       privileged instruction

       FLTBPT	       breakpoint trap

       FLTTRACE	       trace trap (single-step)

       FLTWATCH	       watchpoint trap

       FLTACCESS       memory access fault (bus	error)

       FLTBOUNDS       memory bounds violation

       FLTIOVF	       integer overflow

       FLTIZDIV	       integer zero divide

       FLTFPE	       floating-point exception

       FLTSTACK	       unrecoverable stack fault

       FLTPAGE	       recoverable page	fault

       When not	traced,	a fault	normally results in the	posting	of a signal to
       the lwp that incurred the fault.	If an lwp stops	on a fault, the	signal
       is posted to the	lwp when execution is  resumed	unless	the  fault  is
       cleared	by  PCCFAULT or	by the PRCFAULT	option of PCRUN. FLTPAGE is an
       exception; no signal is posted. The  pr_info  field  in	the  lwpstatus
       structure  identifies  the  signal to be	sent and contains machine-spe-
       cific information about the fault.

   PCCFAULT
       The current fault, if any, is cleared; the associated signal  will  not
       be sent to the specific or representative lwp.

   PCSENTRY PCSEXIT
       These  control  operations instruct the process's lwps to stop on entry
       to or exit from specified system	calls. The set of system calls	to  be
       traced is defined via an	operand	sysset_t structure.

       When  entry to a	system call is being traced, an	lwp stops after	having
       begun the call to the system but	before the system call arguments  have
       been  fetched  from  the	 lwp.  When  exit  from	a system call is being
       traced, an lwp stops on completion of the system	 call  just  prior  to
       checking	 for  signals  and returning to	user level. At this point, all
       return values have been stored into the lwp's registers.

       If an lwp is stopped on entry to	a system call  (PR_SYSENTRY)  or  when
       sleeping	 in an interruptible system call (PR_ASLEEP is set), it	may be
       instructed to go	 directly  to  system  call  exit  by  specifying  the
       PRSABORT	 flag  in a PCRUN control message. Unless exit from the	system
       call is being traced, the lwp returns to	user level showing EINTR.

   PCWATCH
       Set or clear a watched area in the controlled process  from  a  prwatch
       structure operand:

       typedef struct prwatch {
	   uintptr_t pr_vaddr;	/* virtual address of watched area */
	   size_t pr_size;	/* size	of watched area	in bytes */
	   int pr_wflags;	/* watch type flags */
       } prwatch_t;

       pr_vaddr	 specifies  the	 virtual  address  of  an area of memory to be
       watched in the controlled process. pr_size specifies the	 size  of  the
       area,  in  bytes.  pr_wflags  specifies the type	of memory access to be
       monitored as a bit-mask of the following	flags:

       WA_READ		       read access

       WA_WRITE		       write access

       WA_EXEC		       execution access

       WA_TRAPAFTER	       trap after the instruction completes

       If pr_wflags is non-empty, a watched area is established	for  the  vir-
       tual  address  range specified by pr_vaddr and pr_size. If pr_wflags is
       empty, any previously-established watched area starting at  the	speci-
       fied virtual address is cleared;	pr_size	is ignored.

       A  watchpoint  is  triggered  when an lwp in the	traced process makes a
       memory reference	that covers at least one byte of a  watched  area  and
       the memory reference is as specified in pr_wflags. When an lwp triggers
       a watchpoint, it	incurs a watchpoint trap. If FLTWATCH is being traced,
       the  lwp	 stops;	 otherwise, it is sent a SIGTRAP signal; if SIGTRAP is
       being traced and	is not blocked,	the lwp	stops.

       The watchpoint trap occurs  before  the	instruction  completes	unless
       WA_TRAPAFTER  was specified, in which case it occurs after the instruc-
       tion completes. If it occurs before completion, the memory is not modi-
       fied. If	it occurs after	completion, the	memory is modified (if the ac-
       cess is a write access).

       Physical	i/o is an exception for	watchpoint traps.  In  this  instance,
       there  is  no guarantee that memory before the watched area has already
       been modified (or in the	case of	WA_TRAPAFTER, that the memory  follow-
       ing  the	 watched  area has not been modified) when the watchpoint trap
       occurs and the lwp stops.

       pr_info in the lwpstatus	structure contains  information	 pertinent  to
       the watchpoint trap. In particular, the si_addr field contains the vir-
       tual address of the memory reference that triggered the watchpoint, and
       the   si_code  field  contains  one  of	TRAP_RWATCH,  TRAP_WWATCH,  or
       TRAP_XWATCH, indicating read, write, or execute	access,	 respectively.
       The  si_trapafter  field	 is  zero unless WA_TRAPAFTER is in effect for
       this watched area; non-zero indicates that the current  instruction  is
       not  the	instruction that incurred the watchpoint trap. The si_pc field
       contains	the virtual address of the instruction that incurred the trap.

       A watchpoint trap may be	triggered while	executing a system  call  that
       makes reference to the traced process's memory. The lwp that is execut-
       ing the system call incurs the watchpoint trap while still in the  sys-
       tem call. If it stops as	a result, the lwpstatus	structure contains the
       system call number and its arguments. If	the lwp	does not stop,	or  if
       it  is set running again	without	clearing the signal or fault, the sys-
       tem call	fails with EFAULT. If WA_TRAPAFTER was specified,  the	memory
       reference  will	have  completed	and the	memory will have been modified
       (if the access was a write access) when the watchpoint trap occurs.

       If more than one	of WA_READ, WA_WRITE, and WA_EXEC is specified	for  a
       watched	area,  and  a  single  instruction incurs more than one	of the
       specified types,	only one is reported when the watchpoint trap  occurs.
       The  precedence is WA_EXEC, WA_READ, WA_WRITE (WA_EXEC and WA_READ take
       precedence over WA_WRITE), unless WA_TRAPAFTER was specified, in	 which
       case it is WA_WRITE, WA_READ, WA_EXEC (WA_WRITE takes precedence).

       PCWATCH	fails with EINVAL if an	attempt	is made	to specify overlapping
       watched areas or	if pr_wflags contains flags other than those specified
       above.  It  fails  with	ENOMEM if an attempt is	made to	establish more
       watched areas than the system can support (the system can support thou-
       sands).

       The  child  of  a  vfork(2)  borrows the	parent's address space.	When a
       vfork(2)	is executed by a traced	process, all watched areas established
       for  the	parent are suspended until the child terminates	or performs an
       exec(2).	Any watched areas established independently in the  child  are
       cancelled  when	the  parent  resumes  after the	child's	termination or
       exec(2).	PCWATCH	fails with  EBUSY  if  applied	to  the	 parent	 of  a
       vfork(2)	 before	 the child has terminated or performed an exec(2). The
       PR_VFORKP flag is set in	 the  pstatus  structure  for  such  a	parent
       process.

       Certain accesses	of the traced process's	address	space by the operating
       system are immune to watchpoints. The initial construction of a	signal
       stack  frame  when  a  signal is	delivered to an	lwp will not trigger a
       watchpoint trap even if the new	frame  covers  watched	areas  of  the
       stack.  Once the	signal handler is entered, watchpoint traps occur nor-
       mally. On SPARC based machines, register	window overflow	and  underflow
       will not	trigger	watchpoint traps, even if the register window save ar-
       eas cover watched areas of the stack.

       Watched areas are not inherited by child	processes, even	if the	traced
       process's inherit-on-fork mode, PR_FORK,	is set (see PCSET, below). All
       watched areas are cancelled when	the traced process performs a success-
       ful exec(2).

   PCSET PCUNSET
       PCSET sets one or more modes of operation for the traced	process. PCUN-
       SET unsets these	modes. The modes to be set or unset are	 specified  by
       flags in	an operand long	in the control message:

       PR_FORK	       (inherit-on-fork):  When	 set,  the  process's  tracing
		       flags and its inherit-on-fork mode are inherited	by the
		       child  of a fork(2), fork1(2), or vfork(2). When	unset,
		       child processes start with all tracing flags cleared.

       PR_RLC	       (run-on-last-close): When set  and  the	last  writable
		       /proc  file  descriptor referring to the	traced process
		       or any of its lwps is  closed,  all  of	the  process's
		       tracing	flags  and watched areas are cleared, any out-
		       standing	stop directives	are canceled, and if any  lwps
		       are stopped on events of	interest, they are set running
		       as though PCRUN had been	applied	to them.  When	unset,
		       the  process's  tracing flags and watched areas are re-
		       tained and lwps are not set running on last close.

       PR_KLC	       (kill-on-last-close): When set and  the	last  writable
		       /proc  file  descriptor referring to the	traced process
		       or any of its lwps is closed, the process is terminated
		       with SIGKILL.

       PR_ASYNC	       (asynchronous-stop):  When  set,	 a stop	on an event of
		       interest	by one lwp does	not directly affect any	 other
		       lwp  in	the process. When unset	and an lwp stops on an
		       event of	interest other than  PR_REQUESTED,  all	 other
		       lwps in the process are directed	to stop.

       PR_MSACCT       (microstate  accounting):  Microstate accounting	is now
		       continuously enabled. This flag is  deprecated  and  no
		       longer  has  any	effect upon microstate accounting. Ap-
		       plications may toggle this  flag;  however,  microstate
		       accounting will remain enabled regardless.

       PR_MSFORK       (inherit	 microstate accounting): All processes now in-
		       herit microstate	accounting, as it is continuously  en-
		       abled.  This  flag  has	been deprecated	and its	use no
		       longer has any effect upon the behavior	of  microstate
		       accounting.

       PR_BPTADJ       (breakpoint  trap pc adjustment): On -based machines, a
		       breakpoint trap leaves the program  counter  (the  EIP)
		       referring  to  the  breakpointed	 instruction  plus one
		       byte.  When PR_BPTADJ is	set, the  system  will	adjust
		       the  program counter back to the	location of the	break-
		       pointed instruction when	the lwp	stops on a breakpoint.
		       This  flag has no effect	on SPARC based machines, where
		       breakpoint traps	leave the program counter referring to
		       the breakpointed	instruction.

       PR_PTRACE       (ptrace-compatibility): When set, a stop	on an event of
		       interest	by the traced process is reported to the  par-
		       ent  of the traced process by wait(3C), SIGTRAP is sent
		       to the traced process when  it  executes	 a  successful
		       exec(2),	 setuid/setgid flags are not honored for execs
		       performed by the	traced process,	any exec of an	object
		       file that the traced process cannot read	fails, and the
		       process dies when its parent dies. This mode is	depre-
		       cated;  it  is  provided	only to	allow ptrace(3C) to be
		       implemented as a	library	function using /proc.

       It is an	error (EINVAL) to specify flags	 other	than  those  described
       above  or  to  apply  these operations to a system process. The current
       modes are reported  in  the  pr_flags  field  of	 /proc/pid/status  and
       /proc/pid/lwp/lwp/lwpstatus.

   PCSREG
       Set  the	 general  registers for	the specific or	representative lwp ac-
       cording to the operand prgregset_t structure.

       On SPARC	based systems, only the	condition-code bits of the  processor-
       status  register	(R_PSR)	of SPARC V8 (32-bit) processes can be modified
       by PCSREG. Other	privileged registers cannot be modified	at all.

       On -based systems, only certain bits of the flags register (EFL)	can be
       modified	 by  PCSREG: these include the condition codes,	direction-bit,
       and overflow-bit.

       PCSREG fails with EBUSY if the lwp is not stopped on an event of	inter-
       est.

   PCSVADDR
       Set the address at which	execution will resume for the specific or rep-
       resentative lwp from the	operand	long. On SPARC based systems, both %pc
       and  %npc  are set, with	%npc set to the	instruction following the vir-
       tual address. On	-based systems,	only %eip is set. PCSVADDR fails  with
       EBUSY if	the lwp	is not stopped on an event of interest.

   PCSFPREG
       Set the floating-point registers	for the	specific or representative lwp
       according to the	operand	prfpregset_t structure.	 An error (EINVAL)  is
       returned	 if  the system	does not support floating-point	operations (no
       floating-point hardware and the system does not emulate	floating-point
       machine	instructions).	PCSFPREG  fails	 with  EBUSY if	the lwp	is not
       stopped on an event of interest.

   PCSXREG
       Set the extra state registers for the specific  or  representative  lwp
       according  to the architecture-dependent	operand	prxregset_t structure.
       An error	(EINVAL) is returned if	the  system  does  not	support	 extra
       state  registers. PCSXREG fails with EBUSY if the lwp is	not stopped on
       an event	of interest.

   PCSASRS
       Set the ancillary state registers for the  specific  or	representative
       lwp  according  to  the	SPARC  V9  platform-dependent operand asrset_t
       structure. An error (EINVAL) is returned	if either the  target  process
       or  the	controlling  process is	not a 64-bit SPARC V9 process. Most of
       the ancillary state registers are privileged registers that  cannot  be
       modified.  Only	those  that  can  be  modified are set;	all others are
       silently	ignored. PCSASRS fails with EBUSY if the lwp is	not stopped on
       an event	of interest.

   PCAGENT
       Create an agent lwp in the controlled process with register values from
       the operand prgregset_t structure (see PCSREG, above). The agent	lwp is
       created	in  the	 stopped  state	showing	PR_REQUESTED and with its held
       signal set (the signal mask) having  all	 signals  except  SIGKILL  and
       SIGSTOP blocked.

       The  PCAGENT  operation	fails  with  EBUSY unless the process is fully
       stopped via /proc, that is, unless all of the lwps in the  process  are
       stopped either on events	of interest or on PR_SUSPENDED,	or are stopped
       on PR_JOBCONTROL	and have been directed to stop via PCDSTOP.  It	 fails
       with EBUSY if an	agent lwp already exists. It fails with	ENOMEM if sys-
       tem resources for creating new lwps have	been exhausted.

       Any PCRUN operation applied to the process control file or to the  con-
       trol  file  of an lwp other than	the agent lwp fails with EBUSY as long
       as the agent lwp	exists.	The agent lwp must be caused to	 terminate  by
       executing  the  SYS_lwp_exit system call	trap before the	process	can be
       restarted.

       Once the	agent lwp is created, its lwp-ID can be	found by  reading  the
       process	status file. To	facilitate opening the agent lwp's control and
       status files, the directory name	/propc/pid/lwp/agent is	 accepted  for
       lookup  operations as an	invisible alias	for /proc/pid/lwp/lwpid, lwpid
       being the lwp-ID	of the agent lwp (invisible in the sense that the name
       ``agent''  does	not appear in a	directory listing of /proc/pid/lwp ob-
       tained from ls(1), getdents(2), or readdir(3C)).

       The purpose of the agent	lwp is to perform operations in	the controlled
       process on behalf of the	controlling process: to	gather information not
       directly	available via /proc files, or in general to make  the  process
       change  state  in  ways not directly available via /proc	control	opera-
       tions. To make use of an	agent lwp, the controlling process must	be ca-
       pable of	making it execute system calls (specifically, the SYS_lwp_exit
       system call trap). The register values given to the agent lwp  on  cre-
       ation  are  typically  the registers of the representative lwp, so that
       the agent lwp can use its stack.

       The agent lwp is	not allowed to execute any variation of	 the  SYS_fork
       or  SYS_exec  system call traps.	Attempts to do so yield	ENOTSUP	to the
       agent lwp.

       Symbolic	constants for system call trap numbers like  SYS_lwp_exit  and
       SYS_lwp_create can be found in the header file <sys/syscall.h>.

   PCREAD PCWRITE
       Read  or	 write the target process's address space via a	priovec	struc-
       ture operand:

       typedef struct priovec {
	   void	*pio_base;	/* buffer in controlling process */
	   size_t pio_len;	/* size	of read/write request in bytes */
	   off_t pio_offset;	/* virtual address in target process */
       } priovec_t;

       These operations	have the same effect as	pread(2)  and  pwrite(2),  re-
       spectively,  of the target process's address space file.	The difference
       is that more than one PCREAD or PCWRITE control operation can be	 writ-
       ten  to	the  control  file  at once, and they can be interspersed with
       other control operations	in a single write to the control file. This is
       useful,	for example, when planting many	breakpoint instructions	in the
       process's address space,	or when	stepping over a	breakpointed  instruc-
       tion.  Unlike  pread(2) and pwrite(2), no provision is made for partial
       reads or	writes;	if the operation cannot	be  performed  completely,  it
       fails with EIO.

   PCNICE
       The  traced process's nice(2) value is incremented by the amount	in the
       operand long. Only a process with  the  {PRIV_PROC_PRIOCNTL}  privilege
       asserted	 in  its effective set can better a process's priority in this
       way, but	any user may lower the priority. This operation	is  not	 mean-
       ingful for all scheduling classes.

   PCSCRED
       Set  the	 target	process	credentials to the values contained in the pr-
       cred_t structure	operand	(see /proc/pid/cred). The effective, real, and
       saved  user-IDs and group-IDs of	the target process are set. The	target
       process's supplementary groups are  not	changed;  the  pr_ngroups  and
       pr_groups members of the	structure operand are ignored. Only the	privi-
       leged processes can perform this	operation; for	all  others  it	 fails
       with EPERM.

   PCSCREDX
       Operates	 like  PCSCRED	but  also  sets	 the supplementary groups; the
       length of the data  written  with  this	control	 operation  should  be
       "sizeof (prcred_t) + sizeof (gid_t) * (#groups -	1)".

   PCSPRIV
       Set  the	 target	 process  privilege  to	 the  values  contained	in the
       prpriv_t	operand	(see /proc/pid/priv). The effective, permitted,	inher-
       itable,	and  limit  sets  are all changed. Privilege flags can also be
       set. The	process	is made	privilege aware	unless it can relinquish priv-
       ilege awareness.	See privileges(5).

       The  limit  set of the target process cannot be grown. The other	privi-
       lege sets must be subsets of the	intersection of	the effective  set  of
       the  calling  process  with  the	new limit set of the target process or
       subsets of the original values of the sets in the target	process.

       If any of the above restrictions	are not	met, EPERM is returned.	If the
       structure written is improperly formatted, EINVAL is returned.

PROGRAMMING NOTES
       For  security  reasons,	except for the psinfo, usage, lpsinfo, lusage,
       lwpsinfo, and lwpusage files, which are world-readable, and except  for
       privileged  processes,  an  open	 of a /proc file fails unless both the
       user-ID and group-ID of the caller match	those of  the  traced  process
       and  the	process's object file is readable by the caller. The effective
       set of the caller is a superset of both the inheritable and the permit-
       ted  set	of the target process. The limit set of	the caller is a	super-
       set of the limit	set of the target process. Except for the  world-read-
       able  files  just  mentioned,  files corresponding to setuid and	setgid
       processes can be	opened only by the appropriately privileged process.

       A process that is missing the basic privilege  {PRIV_PROC_INFO}	cannot
       see any processes under /proc that it cannot send a signal to.

       A  process that has {PRIV_PROC_OWNER} asserted in its effective set can
       open any	file for reading. To manipulate	or control a process, the con-
       trolling	process	must have at least as many privileges in its effective
       set as the target process has in	its effective, inheritable,  and  per-
       mitted  sets. The limit set of the controlling process must be a	super-
       set of the limit	set of the target process. Additional restrictions ap-
       ply if any of the uids of the target process are	0. See privileges(5).

       Even  if	 held by a privileged process, an open process or lwp file de-
       scriptor	(other than file descriptors for the world-readable files) be-
       comes  invalid  if  the	traced	process	 performs  an exec(2) of a se-
       tuid/setgid object file or an object file that the traced process  can-
       not read. Any operation performed on an invalid file descriptor,	except
       close(2), fails with EAGAIN. In this situation, if  any	tracing	 flags
       are set and the process or any lwp file descriptor is open for writing,
       the process will	have been directed to stop and	its  run-on-last-close
       flag will have been set (see PCSET). This enables a controlling process
       (if it has permission) to reopen	the /proc files	to get new valid  file
       descriptors, close the invalid file descriptors,	unset the run-on-last-
       close flag (if desired),	and proceed. Just closing the invalid file de-
       scriptors  causes the traced process to resume execution	with all trac-
       ing flags cleared. Any process  not  currently  open  for  writing  via
       /proc,  but  that has left-over tracing flags from a previous open, and
       that executes a setuid/setgid or	unreadable object file,	 will  not  be
       stopped but will	have all its tracing flags cleared.

       To wait for one or more of a set	of processes or	lwps to	stop or	termi-
       nate, /proc file	descriptors (other than	those obtained by opening  the
       cwd  or root directories	or by opening files in the fd or object	direc-
       tories) can be used in a	poll(2)	system call. When  requested  and  re-
       turned,	either	of  the	polling	events POLLPRI or POLLWRNORM indicates
       that the	process	or lwp stopped on an event of interest.	Although  they
       cannot  be requested, the polling events	POLLHUP, POLLERR, and POLLNVAL
       may be returned.	POLLHUP	indicates that the process or lwp  has	termi-
       nated.  POLLERR	indicates that the file	descriptor has become invalid.
       POLLNVAL	is returned immediately	if POLLPRI or POLLWRNORM is  requested
       on  a  file  descriptor referring to a system process (see PCSTOP). The
       requested events	may be empty to	wait simply for	termination.

       /proc

	   directory (list of processes)

       /proc/pid

	   specific process directory

       /proc/self

	   alias for a process's own directory

       /proc/pid/as

	   address space file

       /proc/pid/ctl

	   process control file

       /proc/pid/status

	   process status

       /proc/pid/lstatus

	   array of lwp	status structs

       /proc/pid/psinfo

	   process ps(1) info

       /proc/pid/lpsinfo

	   array of lwp	ps(1) info structs

       /proc/pid/map

	   address space map

       /proc/pid/rmap

	   reserved address map

       /proc/pid/cred

	   process credentials

       /proc/pid/priv

	   process privileges

       /proc/pid/sigact

	   process signal actions

       /proc/pid/auxv

	   process aux vector

       /proc/pid/ldt

	   process LDT ( only)

       /proc/pid/usage

	   process usage

       /proc/pid/lusage

	   array of lwp	usage structs

       /proc/pid/path

	   symbolic links to process open files

       /proc/pid/pagedata

	   process page	data

       /proc/pid/watch

	   active watchpoints

       /proc/pid/cwd

	   alias for the current working directory

       /proc/pid/root

	   alias for the root directory

       /proc/pid/fd

	   directory (list of open files)

       /proc/pid/fd/*

	   aliases for process's open files

       /proc/pid/object

	   directory (list of mapped files)

       /proc/pid/object/a.out

	   alias for process's executable file

       /proc/pid/object/*

	   aliases for other mapped files

       /proc/pid/lwp

	   directory (list of lwps)

       /proc/pid/lwp/lwpid

	   specific lwp	directory

       /proc/pid/lwp/agent

	   alias for the agent lwp directory

       /proc/pid/lwp/lwpid/lwpctl

	   lwp control file

       /proc/pid/lwp/lwpid/lwpstatus

	   lwp status

       /proc/pid/lwp/lwpid/lwpsinfo

	   lwp ps(1) info

       /proc/pid/lwp/lwpid/lwpusage

	   lwp usage

       /proc/pid/lwp/lwpid/gwindows

	   register windows (SPARC only)

       /proc/pid/lwp/lwpid/xregs

	   extra state registers

       /proc/pid/lwp/lwpid/asrs

	   ancillary state registers (SPARC V9 only)

       ls(1),  ps(1),  chroot(1M),  alarm(2),  brk(2),	chdir(2),   chroot(2),
       close(2),  creat(2),  dup(2), exec(2), fcntl(2),	fork(2), fork1(2), fs-
       tat(2), getdents(2), getustack(2), kill(2), lseek(2), mmap(2), nice(2),
       open(2),	 poll(2),  pread(2),  ptrace(3C),  pwrite(2),  read(2),	 read-
       link(2),	readv(2), shmget(2), sigaction(2),  sigaltstack(2),  vfork(2),
       write(2),  writev(2), _stack_grow(3C), readdir(3C), pthread_create(3C),
       pthread_join(3C),  siginfo.h(3HEAD),  signal.h(3HEAD),  thr_create(3C),
       thr_join(3C),   types32.h(3HEAD),   ucontext.h(3HEAD),  wait(3C),  con-
       tract(4), process(4), lfcompile(5), privileges(5)

       Errors that can occur in	addition to  the  errors  normally  associated
       with file system	access:

       E2BIG	       Data  to	be returned in a read(2) of the	page data file
		       exceeds the size	of the read  buffer  provided  by  the
		       caller.

       EACCES	       An attempt was made to examine a	process	that ran under
		       a  different  uid  than	the  controlling  process  and
		       {PRIV_PROC_OWNER}  was  not  asserted  in the effective
		       set.

       EAGAIN	       The traced process has performed	an exec(2)  of	a  se-
		       tuid/setgid  object  file  or of	an object file that it
		       cannot read; all	further	operations on the  process  or
		       lwp  file  descriptor (except close(2)) elicit this er-
		       ror.

       EBUSY	       PCSTOP, PCDSTOP,	PCWSTOP, or PCTWSTOP was applied to  a
		       system process; an exclusive open(2) was	attempted on a
		       /proc file for a	 process  already  open	 for  writing;
		       PCRUN,  PCSREG,	PCSVADDR, PCSFPREG, or PCSXREG was ap-
		       plied to	a process or lwp not stopped on	 an  event  of
		       interest;  an  attempt  was made	to mount /proc when it
		       was already mounted; PCAGENT was	applied	to  a  process
		       that was	not fully stopped or that already had an agent
		       lwp.

       EINVAL	       In general, this	means that some	invalid	 argument  was
		       supplied	 to  a	system	call. A	non-exhaustive list of
		       conditions eliciting this  error	 includes:  a  control
		       message	operation  code	 is undefined; an out-of-range
		       signal number was specified  with  PCSSIG,  PCKILL,  or
		       PCUNKILL; SIGKILL was specified with PCUNKILL; PCSFPREG
		       was applied on a	system that does not support floating-
		       point  operations; PCSXREG was applied on a system that
		       does not	support	extra state registers.

       EINTR	       A signal	was received by	the controlling	process	 while
		       waiting	for  the traced	process	or lwp to stop via PC-
		       STOP, PCWSTOP, or PCTWSTOP.

       EIO	       A write(2) was attempted	at an illegal address  in  the
		       traced process.

       ENOENT	       The  traced  process  or	lwp has	terminated after being
		       opened. The basic privilege {PRIV_PROC_INFO} is not as-
		       serted  in the effective	set of the calling process and
		       the calling process cannot send a signal	to the	target
		       process.

       ENOMEM	       The  system-imposed  limit  on  the number of page data
		       file  descriptors   was	 reached   on	an   open   of
		       /proc/pid/pagedata; an attempt was made with PCWATCH to
		       establish more watched areas than the system  can  sup-
		       port;  the PCAGENT operation was	issued when the	system
		       was out of resources for	creating lwps.

       ENOSYS	       An attempt was made to perform an unsupported operation
		       (such  as  creat(2), link(2), or	unlink(2)) on an entry
		       in /proc.

       EOVERFLOW       A 32-bit	controlling process attempted to read or write
		       the  as	file  or  attempted  to	read the map, rmap, or
		       pagedata	file of	a 64-bit target	process. A 32-bit con-
		       trolling	 process attempted to apply one	of the control
		       operations PCSREG, PCSXREG, PCSVADDR, PCWATCH, PCAGENT,
		       PCREAD, PCWRITE to a 64-bit target process.

       EPERM	       The  process that issued	the PCSCRED or PCSCREDX	opera-
		       tion did	not have the {PRIV_PROC_SETID}	privilege  as-
		       serted in its effective set, or the process that	issued
		       the PCNICE operation did	not have the {PRIV_PROC_PRIOC-
		       NTL} in its effective set.

		       An  attempt  was	made to	control	a process of which the
		       E, P, and I privilege sets were not a subset of the ef-
		       fective set of the controlling process or the limit set
		       of the controlling process is not a superset  of	 limit
		       set of the controlled process.

		       Any  of	the uids of the	target process are 0 or	an at-
		       tempt was made to change	any of the uids	to 0 using PC-
		       SCRED  and  the	security policy	imposed	additional re-
		       strictions. See privileges(5).

       Descriptions of structures in this document  include  only  interesting
       structure  elements,  not  filler and padding fields, and may show ele-
       ments out of order for descriptive clarity. The actual structure	 defi-
       nitions are contained in	<procfs.h>.

       Because	the old	ioctl(2)-based version of /proc	is currently supported
       for binary compatibility	with old applications, the top-level directory
       for  a  process,	 /proc/pid,  is	 not  world-readable, but it is	world-
       searchable. Thus, anyone	can open /proc/pid/psinfo  even	 though	 ls(1)
       applied to /proc/pid will fail for anyone but the owner or an appropri-
       ately privileged	process. Support for the old ioctl(2)-based version of
       /proc  will be dropped in a future release, at which time the top-level
       directory for a process will be made world-readable.

       On SPARC	based machines,	the types gregset_t and	fpregset_t defined  in
       <sys/regset.h> are similar to but not the same as the types prgregset_t
       and prfpregset_t	defined	in <procfs.h>.

				  24 May 2005			       proc(4)

NAME | DIRECTORY STRUCTURE | CONTROL MESSAGES | PROGRAMMING NOTES

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