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PROC(5)                    Linux Programmer's Manual                   PROC(5)

NAME
       proc - process information pseudo-filesystem

DESCRIPTION
       /proc is a pseudo-filesystem which is used as an interface to kernel
       data structures rather than reading and interpreting /dev/kmem.  Most
       of it is read-only, but some files allow kernel variables to be
       changed.

       The following outline gives a quick tour through the /proc hierarchy.

       [number]
              There is a numerical subdirectory for each running process; the
              subdirectory is named by the process ID.  Each contains the
              following pseudo-files and directories.

              cmdline
                     This holds the complete command line for the process,
                     unless the whole process has been swapped out, or unless
                     the process is a zombie.  In either of these later cases,
                     there is nothing in this file: i.e. a read on this file
                     will return 0 characters.  The command line arguments
                     appear in this file as a set of null-separated strings,
                     with a further null byte after the last string.

              cwd    This is a link to the current working directory of the
                     process.  To find out the cwd of process 20, for
                     instance, you can do this:

                     cd /proc/20/cwd; /bin/pwd

                     Note that the pwd command is often a shell builtin, and
                     might not work properly. In bash, you may use pwd -P.

              environ
                     This file contains the environment for the process.  The
                     entries are separated by null characters, and there may
                     be a null character at the end.  Thus, to print out the
                     environment of process 1, you would do:

                     (cat /proc/1/environ; echo) | tr "\000" "\n"

                     (For a reason why one should want to do this, see
                     lilo(8).)

              exe    Under Linux 2.2 and 2.4 exe is a symbolic link containing
                     the actual path name of the executed command.  The exe
                     symbolic link can be dereferenced normally - attempting
                     to open exe will open the executable.  You can even type
                     /proc/[number]/exe to run another copy of the same
                     process as [number].

                     Under Linux 2.0 and earlier exe is a pointer to the
                     binary which was executed, and appears as a symbolic
                     link. A readlink(2) call on the exe special file under
                     Linux 2.0 returns a string in the format:

                     [device]:inode

                     For example, [0301]:1502 would be inode 1502 on device
                     major 03 (IDE, MFM, etc. drives) minor 01 (first
                     partition on the first drive).

                     find(1) with the -inum option can be used to locate the
                     file.

              fd     This is a subdirectory containing one entry for each file
                     which the process has open, named by its file descriptor,
                     and which is a symbolic link to the actual file (as the
                     exe entry does).  Thus, 0 is standard input, 1 standard
                     output, 2 standard error, etc.

                     Programs that will take a filename, but will not take the
                     standard input, and which write to a file, but will not
                     send their output to standard output, can be effectively
                     foiled this way, assuming that -i is the flag designating
                     an input file and -o is the flag designating an output
                     file:
                     foobar -i /proc/self/fd/0 -o /proc/self/fd/1 ...
                     and you have a working filter.  Note that this will not
                     work for programs that seek on their files, as the files
                     in the fd directory are not seekable.

                     /proc/self/fd/N is approximately the same as /dev/fd/N in
                     some UNIX and UNIX-like systems.  Most Linux MAKEDEV
                     scripts symbolically link /dev/fd to /proc/self/fd, in
                     fact.

              maps   A file containing the currently mapped memory regions and
                     their access permissions.

                     The format is:

        address           perms offset  dev   inode      pathname
        08048000-08056000 r-xp 00000000 03:0c 64593      /usr/sbin/gpm
        08056000-08058000 rw-p 0000d000 03:0c 64593      /usr/sbin/gpm
        08058000-0805b000 rwxp 00000000 00:00 0
        40000000-40013000 r-xp 00000000 03:0c 4165       /lib/ld-2.2.4.so
        40013000-40015000 rw-p 00012000 03:0c 4165       /lib/ld-2.2.4.so
        4001f000-40135000 r-xp 00000000 03:0c 45494      /lib/libc-2.2.4.so
        40135000-4013e000 rw-p 00115000 03:0c 45494      /lib/libc-2.2.4.so
        4013e000-40142000 rw-p 00000000 00:00 0
        bffff000-c0000000 rwxp 00000000 00:00 0

              where address is the address space in the process that it
              occupies, perms is a set of permissions:

                   r = read
                   w = write
                   x = execute
                   s = shared
                   p = private (copy on write)

              offset is the offset into the file/whatever, dev is the device
              (major:minor), and inode is the inode on that device.  0
              indicates that no inode is associated with the memory region, as
              the case would be with bss.

              Under Linux 2.0 there is no field giving pathname.

              mem    Via the mem file one can access the pages of a process's
                     memory through open(2), read(2), and fseek(3).

              root   Unix and Linux support the idea of a per-process root of
                     the filesystem, set by the chroot(2) system call.  Root
                     points to the file system root, and behaves as exe, fd/*,
                     etc. do.

              stat   Status information about the process.  This is used by
                     ps(1).  It is defined in /usr/src/linux/fs/proc/array.c.

                     The fields, in order, with their proper scanf(3) format
                     specifiers, are:

                     pid %d The process id.

                     comm %s
                            The filename of the executable, in parentheses.
                            This is visible whether or not the executable is
                            swapped out.

                     state %c
                            One character from the string "RSDZTW" where R is
                            running, S is sleeping in an interruptible wait, D
                            is waiting in uninterruptible disk sleep, Z is
                            zombie, T is traced or stopped (on a signal), and
                            W is paging.

                     ppid %d
                            The PID of the parent.

                     pgrp %d
                            The process group ID of the process.

                     session %d
                            The session ID of the process.

                     tty_nr %d
                            The tty the process uses.

                     tpgid %d
                            The process group ID of the process which
                            currently owns the tty that the process is
                            connected to.

                     flags %lu
                            The flags of the process.  The math bit is decimal
                            4, and the traced bit is decimal 10.

                     minflt %lu
                            The number of minor faults the process has made
                            which have not required loading a memory page from
                            disk.

                     cminflt %lu
                            The number of minor faults that the process and
                            its children have made.

                     majflt %lu
                            The number of major faults the process has made
                            which have required loading a memory page from
                            disk.

                     cmajflt %lu
                            The number of major faults that the process and
                            its children have made.

                     utime %lu
                            The number of jiffies that this process has been
                            scheduled in user mode.

                     stime %lu
                            The number of jiffies that this process has been
                            scheduled in kernel mode.

                     cutime %ld
                            The number of jiffies that this process and its
                            children have been scheduled in user mode.

                     cstime %ld
                            The number of jiffies that this process and its
                            children have been scheduled in kernel mode.

                     priority %ld
                            The standard nice value, plus fifteen.  The value
                            is never negative in the kernel.

                     nice %ld
                            The nice value ranges from 19 (nicest) to -19 (not
                            nice to others).

                     0 %ld  This value is hard coded to 0 as a placeholder for
                            a removed field.

                     itrealvalue %ld
                            The time in jiffies before the next SIGALRM is
                            sent to the process due to an interval timer.

                     starttime %lu
                            The time in jiffies the process started after
                            system boot.

                     vsize %lu
                            Virtual memory size in bytes.

                     rss %ld
                            Resident Set Size: number of pages the process has
                            in real memory, minus 3 for administrative
                            purposes. This is just the pages which count
                            towards text, data, or stack space.  This does not
                            include pages which have not been demand-loaded
                            in, or which are swapped out.

                     rlim %lu
                            Current limit in bytes on the rss of the process
                            (usually 4,294,967,295).

                     startcode %lu
                            The address above which program text can run.

                     endcode %lu
                            The address below which program text can run.

                     startstack %lu
                            The address of the start of the stack.

                     kstkesp %lu
                            The current value of esp (stack pointer), as found
                            in the kernel stack page for the process.

                     kstkeip %lu
                            The current EIP (instruction pointer).

                     signal %lu
                            The bitmap of pending signals (usually 0).

                     blocked %lu
                            The bitmap of blocked signals (usually 0, 2 for
                            shells).

                     sigignore %lu
                            The bitmap of ignored signals.

                     sigcatch %lu
                            The bitmap of catched signals.

                     wchan %lu
                            This is the "channel" in which the process is
                            waiting.  It is the address of a system call, and
                            can be looked up in a namelist if you need a
                            textual name.  (If you have an up-to-date
                            /etc/psdatabase, then try ps -l to see the WCHAN
                            field in action.)

                     nswap %lu
                            Number of pages swapped - not maintained.

                     cnswap %lu
                            Cumulative nswap for child processes.

                     exit_signal %d
                            Signal to be sent to parent when we die.

                     processor %d
                            Processor number last executed on.

              statm  Provides information about memory status in pages.  The
                     columns are:
                      size       total program size
                      resident   resident set size
                      share      shared pages
                      trs        text (code)
                      drs        data/stack
                      lrs        library
                      dt         dirty pages

              status Provides much of the information in stat and statm in an
                     format that's easier for humans to parse.

       bus    Contains subdirectories for installed busses.

              pci    Contains various bus subdirectories and pseudo-files
                     containing information about pci busses, installed
                     devices, and device drivers.  Some of these files are not
                     ASCII.

                     devices
                            Information about pci devices.  They may be
                            accessed through lspci(8) and setpci(8).

       cmdline
              Argments passed to the Linux kernel at boot time.  Often done
              via a boot manager such as lilo(1).

       cpuinfo
              This is a collection of CPU and system architecture dependent
              items, for each supported architecture a different list.  Two
              common entries are processor which gives CPU number and
              bogomips; a system constant that is calculated during kernel
              initialization.  SMP machines have information for each CPU.

       devices
              Text listing of major numbers and device groups.  This can be
              used by MAKEDEV scripts for consistency with the kernel.

       dma    This is a list of the registered ISA DMA (direct memory access)
              channels in use.

       driver Empty subdirectory.

       execdomains
              List of the execution domains (ABI personalities).

       fb     Frame buffer information when CONFIG_FB is defined during kernel
              compilation.

       filesystems
              A text listing of the filesystems which were compiled into the
              kernel.  Incidentally, this is used by mount(1) to cycle through
              different filesystems when none is specified.

       ide    ide exists on systems with the ide bus.  There are directories
              for each ide channel and attached device.  Files include:

              cache              buffer size in KB
              capacity           number of sectors
              driver             driver version
              geometry           physical and logical geometry
              identify           in hexidecimal
              media              media type
              model              manufacturer's model number
              settings           drive settings
              smart_thresholds   in hexidecimal
              smart_values       in hexidecimal

              The hdparm(8) utility provides access to this information in a
              friendly format.

       interrupts
              This is used to record the number of interrupts per each IRQ on
              (at least) the i386 architechure.  Very easy to read formatting,
              done in ASCII.

       iomem  I/O memory map in Linux 2.4.

       ioports
              This is a list of currently registered Input-Output port regions
              that are in use.

       kcore  This file represents the physical memory of the system and is
              stored in the ELF core file format.  With this pseudo-file, and
              an unstripped kernel (/usr/src/linux/vmlinux) binary, GDB can be
              used to examine the current state of any kernel data structures.

              The total length of the file is the size of physical memory
              (RAM) plus 4KB.

       kmsg   This file can be used instead of the syslog(2) system call to
              read kernel log messages.  A process must have superuser
              privileges to read this file, and only one process should make
              use of this facility or syslog(2) to read this file.

              Information in this file is retrieved with the dmesg(8) program.

       ksyms  This holds the kernel exported symbol definitions used by the
              modules(X) tools to dynamically link and bind loadable modules.

       loadavg
              The load average numbers give the number of jobs in the run
              queue (state R) or waiting for disk I/O (state D) averaged over
              1, 5, and 15 minutes.  They are the same as the load average
              numbers given by uptime(1) and other programs.

       locks  This file shows current file locks (flock(2) and fcntl(2)) and
              leases (fcntl(2)).

       malloc This file is only present if CONFIGDEBUGMALLOC was defined
              during compilation.

       meminfo
              This is used by free(1) to report the amount of free and used
              memory (both physical and swap) on the system as well as the
              shared memory and buffers used by the kernel.

              It is in the same format as free(1), except in bytes rather than
              KB.

       mounts This is a list of all the file systems currently mounted on the
              system.  The format of this file is documented in fstab(5).

       modules
              A text list of the modules that have been loaded by the system.
              See also lsmod(8).

       mtrr   Memory Type Range Registers.  See
              /usr/src/linux/Documentation/mtrr.txt for details.

       net    various net pseudo-files, all of which give the status of some
              part of the networking layer.  These files contain ASCII
              structures and are, therefore, readable with cat.  However, the
              standard netstat(8) suite provides much cleaner access to these
              files.

              arp    This holds an ASCII readable dump of the kernel ARP table
                     used for address resolutions. It will show both
                     dynamically learned and pre-programmed ARP entries.  The
                     format is:

        IP address     HW type   Flags     HW address          Mask   Device
        192.168.0.50   0x1       0x2       00:50:BF:25:68:F3   *      eth0
        192.168.0.250  0x1       0xc       00:00:00:00:00:00   *      eth0

              Here 'IP address' is the IPv4 address of the machine and the 'HW
              type' is the hardware type of the address from RFC 826. The
              flags are the internal flags of the ARP structure (as defined in
              /usr/include/linux/if_arp.h) and the 'HW address' is the
              physical layer mapping for that IP address if it is known.

              dev    The dev pseudo-file contains network device status
                     information. This gives the number of received and sent
                     packets, the number of errors and collisions and other
                     basic statistics. These are used by the ifconfig(8)
                     program to report device status.  The format is:

 Inter-|   Receive                                                |  Transmit
  face |bytes    packets errs drop fifo frame compressed multicast|bytes    packets errs drop fifo colls carrier compressed
     lo: 2776770   11307    0    0    0     0          0         0  2776770   11307    0    0    0     0       0          0
   eth0: 1215645    2751    0    0    0     0          0         0  1782404    4324    0    0    0   427       0          0
   ppp0: 1622270    5552    1    0    0     0          0         0   354130    5669    0    0    0     0       0          0
   tap0:    7714      81    0    0    0     0          0         0     7714      81    0    0    0     0       0          0

              rarp   This file uses the same format as the arp file and
                     contains the current reverse mapping database used to
                     provide rarp(8) reverse address lookup services. If RARP
                     is not configured into the kernel, this file will not be
                     present.

              raw    Holds a dump of the RAW socket table. Much of the
                     information is not of use apart from debugging. The 'sl'
                     value is the kernel hash slot for the socket, the 'local
                     address' is the local address and protocol number
                     pair."St" is the internal status of the socket. The
                     "tx_queue" and "rx_queue" are the outgoing and incoming
                     data queue in terms of kernel memory usage. The "tr",
                     "tm->when", and "rexmits" fields are not used by RAW. The
                     uid field holds the creator euid of the socket.

              snmp   This file holds the ASCII data needed for the IP, ICMP,
                     TCP, and UDP management information bases for an snmp
                     agent.

              tcp    Holds a dump of the TCP socket table. Much of the
                     information is not of use apart from debugging. The "sl"
                     value is the kernel hash slot for the socket, the "local
                     address" is the local address and port number pair. The
                     "remote address" is the remote address and port number
                     pair (if connected). 'St' is the internal status of the
                     socket. The 'tx_queue' and 'rx_queue' are the outgoing
                     and incoming data queue in terms of kernel memory usage.
                     The "tr", "tm->when", and "rexmits" fields hold internal
                     information of the kernel socket state and are only
                     useful for debugging. The uid field holds the creator
                     euid of the socket.

              udp    Holds a dump of the UDP socket table. Much of the
                     information is not of use apart from debugging. The "sl"
                     value is the kernel hash slot for the socket, the "local
                     address" is the local address and port number pair. The
                     "remote address" is the remote address and port number
                     pair (if connected). "St" is the internal status of the
                     socket. The "tx_queue" and "rx_queue" are the outgoing
                     and incoming data queue in terms of kernel memory usage.
                     The "tr", "tm->when", and "rexmits" fields are not used
                     by UDP. The uid field holds the creator euid of the
                     socket.  The format is:

 sl  local_address rem_address   st tx_queue rx_queue tr rexmits  tm->when uid
  1: 01642C89:0201 0C642C89:03FF 01 00000000:00000001 01:000071BA 00000000 0
  1: 00000000:0801 00000000:0000 0A 00000000:00000000 00:00000000 6F000100 0
  1: 00000000:0201 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0

              unix   Lists the UNIX domain sockets present within the system
                     and their status.  The format is:
                     Num RefCount Protocol Flags    Type St Path
                      0: 00000002 00000000 00000000 0001 03
                      1: 00000001 00000000 00010000 0001 01 /dev/printer

              Here 'Num' is the kernel table slot number, 'RefCount' is the
              number of users of the socket, 'Protocol' is currently always 0,
              'Flags' represent the internal kernel flags holding the status
              of the socket. Currently, type is always '1' (Unix domain
              datagram sockets are not yet supported in the kernel). 'St' is
              the internal state of the socket and Path is the bound path (if
              any) of the socket.

       partitions
              Contains major and minor numbers of each partition as well as
              number of blocks and partition name.

       pci    This is a listing of all PCI devices found during kernel
              initialization and their configuration.

       scsi   A directory with the scsi midlevel pseudo-file and various SCSI
              lowlevel driver directories, which contain a file for each SCSI
              host in this system, all of which give the status of some part
              of the SCSI IO subsystem.  These files contain ASCII structures
              and are, therefore, readable with cat.

              You can also write to some of the files to reconfigure the
              subsystem or switch certain features on or off.

              scsi   This is a listing of all SCSI devices known to the
                     kernel. The listing is similar to the one seen during
                     bootup.  scsi currently supports only the add-single-
                     device command which allows root to add a hotplugged
                     device to the list of known devices.

                     An echo 'scsi add-single-device 1 0 5 0' >
                     /proc/scsi/scsi will cause host scsi1 to scan on SCSI
                     channel 0 for a device on ID 5 LUN 0. If there is already
                     a device known on this address or the address is invalid,
                     an error will be returned.

              drivername
                     drivername can currently be NCR53c7xx, aha152x, aha1542,
                     aha1740, aic7xxx, buslogic, eata_dma, eata_pio, fdomain,
                     in2000, pas16, qlogic, scsi_debug, seagate, t128,
                     u15-24f, ultrastore, or wd7000.  These directories show
                     up for all drivers that registered at least one SCSI HBA.
                     Every directory contains one file per registered host.
                     Every host-file is named after the number the host was
                     assigned during initialization.

                     Reading these files will usually show driver and host
                     configuration, statistics etc.

                     Writing to these files allows different things on
                     different hosts.  For example, with the latency and
                     nolatency commands, root can switch on and off command
                     latency measurement code in the eata_dma driver. With the
                     lockup and unlock commands, root can control bus lockups
                     simulated by the scsi_debug driver.

       self   This directory refers to the process accessing the /proc
              filesystem, and is identical to the /proc directory named by the
              process ID of the same process.

       slabinfo
              Information about kernel caches.  The columns are:
              cache-name
              num-active-objs
              total-objs
              object-size
              num-active-slabs
              total-slabs
              num-pages-per-slab
              See slabinfo(5) for details.

       stat   kernel/system statistics.  Varies with architecture.  Common
              entries include:

              cpu  3357 0 4313 1362393
                     The number of jiffies (1/100ths of a second) that the
                     system spent in user mode, user mode with low priority
                     (nice), system mode, and the idle task, respectively.
                     The last value should be 100 times the second entry in
                     the uptime pseudo-file.

              page 5741 1808
                     The number of pages the system paged in and the number
                     that were paged out (from disk).

              swap 1 0
                     The number of swap pages that have been brought in and
                     out.

              intr 1462898
                     The number of interrupts received from the system boot.

              disk_io: (2,0):(31,30,5764,1,2) (3,0):...
                     (major,minor):(noinfo, read_io_ops, blks_read,
                     write_io_ops, blks_written)

              ctxt 115315
                     The number of context switches that the system underwent.

              btime 769041601
                     boot time, in seconds since the epoch (January 1, 1970).

              processes 86031
                     Number of forks since boot.

       swaps  Swap areas in use.  See also swapon(8).

       sys    This directory (present since 1.3.57) contains a number of files
              and subdirectories corresponding to kernel variables.  These
              variables can be read and sometimes modified using the proc file
              system, and the sysctl(2) system call. Presently, there are
              subdirectories abi, debug, dev, fs, kernel, net, proc, sunrpc
              and vm that each contain more files and subdirectories.

              abi    This directory may be empty.  On some systems, it is not
                     present.

              debug  This directory may be empty.

              dev    This directory contains device specific information (eg
                     dev/cdrom/info).  On some systems, it may be empty.

              fs     This contains the subdirectory binfmt_misc and files
                     dentry-state, dir-notify-enable, dquot-nr, file-max,
                     file-nr, inode-max, inode-nr, inode-state,
                     lease-break-time, leases-enable, overflowgid, overflowuid
                     super-max and super-nr with function fairly clear from
                     the name.

              Documentation for the files in /proc/sys/binfmt_misc is in the
              kernel sources in Documentation/binfmt_misc.txt.

              The file dentry-state contains six numbers, nr_dentry,
              nr_unused, age_limit (age in seconds), want_pages (pages
              requested by system) and two dummy values.  nr_dentry seems to
              be 0 all the time.  nr_unused seems to be the number of unused
              dentries.  age_limit is the age in seconds after which dcache
              entries can be reclaimed when memory is short and want_pages is
              nonzero when the kernel has called shrink_dcache_pages() and the
              dcache isn't pruned yet.

              The file dir-notify-enable can be used to disable or enable the
              dnotify interface described in fcntl(2) on a system-wide basis.
              A value of 0 in this file disables the interface, and a value of
              1 enables it.

              The file dquot-max shows the maximum number of cached disk quota
              entries.  On some (2.4) systems, it is not present.  If the
              number of free cached disk quotas is very low and you have some
              awesome number of simultaneous system users, you might want to
              raise the limit.

              The file dquot-nr shows the number of allocated disk quota
              entries and the number of free disk quota entries.

              The file file-max is a system-wide limit on the number of open
              files for all processes.  (See also setrlimit(2), which can be
              used by a process to set the per-process limit, RLIMIT_NOFILE,
              on the number of files it may open.)  If you get lots of error
              messages about running out of file handles, try increasing this
              value:

              echo 100000 > /proc/sys/fs/file-max

              The kernel constant NR_OPEN imposes an upper limit on the value
              that may be placed in file-max.

              If you increase file-max, be sure to increase inode-max to 3-4
              times the new value of file-max, or you will run out of inodes.

              The (read-only) file file-nr gives the number of files presently
              opened.  It contains three numbers: The number of allocated file
              handles, the number of free file handles and the maximum number
              of file handles.  The kernel allocates file handles dynamically,
              but it doesn't free them again.  If the number of allocated
              files is close to the maximum, you should consider increasing
              the maximum.  When the number of free file handles is large,
              you've encountered a peak in your usage of file handles and you
              probably don't need to increase the maximum.

              The file inode-max contains the maximum number of in-memory
              inodes.  On some (2.4) systems, it may not be present. This
              value should be 3-4 times larger than the value in file-max,
              since stdin, stdout and network sockets also need an inode to
              handle them. When you regularly run out of inodes, you need to
              increase this value.

              The file inode-nr contains the first two values from inode-
              state.

              The file inode-state contains seven numbers: nr_inodes,
              nr_free_inodes, preshrink and four dummy values.  nr_inodes is
              the number of inodes the system has allocated.  This can be
              slightly more than inode-max because Linux allocates them one
              pageful at a time.  nr_free_inodes represents the number of free
              inodes.  preshrink is nonzero when the nr_inodes > inode-max and
              the system needs to prune the inode list instead of allocating
              more.

              The file lease-break-time specifies the grace period that the
              kernel grants to a process holding a file lease (fcntl(2)) after
              it has sent a signal to that process notifying it that another
              process is waiting to open the file.  If the lease holder does
              not remove or downgrade the lease within this grace period, the
              kernel forcibly breaks the lease.

              The file leases-enable can be used to enable or disable file
              leases (fcntl(2)) on a system-wide basis.  If this file contains
              the value 0, leases are disabled.  A non-zero value enables
              leases.

              The files overflowgid and  overflowuid allow you to change the
              value of the fixed UID and GID.  The default is 65534.  Some
              filesystems only support 16-bit UIDs and GIDs, although in Linux
              UIDs and GIDs are 32 bits. When one of these filesystems is
              mounted with writes enabled, any UID or GID that would exceed
              65535 is translated to the overflow value before being written
              to disk.

              The file super-max controls the maximum number of superblocks,
              and thus the maximum number of mounted filesystems the kernel
              can have. You only need to increase super-max if you need to
              mount more filesystems than the current value in super-max
              allows you to.  The file super-nr contains the number of
              filesystems currently mounted.

              kernel This directory contains files acct, cad_pid, cap-bound,
                     core_uses_pid,  ctrl-alt-del, dentry-state, domainname,
                     hostname,  htab-reclaim (PowerPC only),
                     java-appletviewer (binfmt_java, obsolete),
                     java-interpreter (binfmt_java, obsolete), l2cr (PowerPC
                     only),  modprobe, msgmax, msgmnb,  msgmni, osrelease,
                     ostype, overflowgid, overflowuid,  panic, powersave-nap
                     (PowerPC only), printk, random,  real-root-dev,
                     reboot-cmd (SPARC only), rtsig-max,  rtsig-nr, sem,
                     sg-big-buff,  shmall, shmmax, shmmni, sysrq, tainted,
                     threads-max,  version and zero-paged (PowerPC only)  with
                     function fairly clear from the name.

              The file acct contains three numbers: highwater, lowwater and
              frequency.  If BSD-style process accounting is enabled these
              values control its behaviour. If free space on filesystem where
              the log lives goes below lowwater percent accounting suspends.
              If free space gets above highwater percent accounting resumes.
              Frequency determines how often the kernel checks the amount of
              free space (value is in seconds). Default values are 4, 2 and
              30.  That is, suspend accounting if <= 2% of space is free;
              resume it if >= 4% of space is free; consider information about
              amount of free space valid for 30 seconds.

              The file cap-bound holds the value of the kernel capability
              bounding set (expressed as a signed decimal number).  This set
              is ANDed against the capabilities permitted to a process during
              exec.

              The file core_uses_pid can be used control the naming of a core
              dump file on Linux 2.4.  If this file contains the value 0, then
              a core dump file is simply named core.  If this file contains a
              non-zero value, then the core dump file includes the process ID
              in a name of the form core.PID.

              The file ctrl-alt-del controls the handling of Ctrl-Alt-Del from
              the keyboard.  When the value in this file is 0, Ctrl-Alt-Del is
              trapped and sent to the init(1) program to handle a graceful
              restart.  When the value is > 0, Linux's reaction to a Vulcan
              Nerve Pinch (tm) will be an immediate reboot, without even
              syncing its dirty buffers.  Note: when a program (like dosemu)
              has the keyboard in 'raw' mode, the ctrl-alt-del is intercepted
              by the program before it ever reaches the kernel tty layer, and
              it's up to the program to decide what to do with it.

              The files domainname and  hostname can be used to set the NIS/YP
              domainname and the hostname of your box in exactly the same way
              as the commands domainname and hostname, i.e.:

              # echo "darkstar" > /proc/sys/kernel/hostname
              # echo "mydomain" > /proc/sys/kernel/domainname

              has the same effect as

              # hostname "darkstar"
              # domainname "mydomain"

              Note, however, that the classic darkstar.frop.org has the
              hostname "darkstar" and DNS (Internet Domain Name Server)
              domainname "frop.org", not to be confused with the NIS (Network
              Information Service) or YP (Yellow Pages) domainname. These two
              domain names are in general different. For a detailed discussion
              see the hostname(1) man page.

              If the file htab-reclaim (PowerPC only) is set to a non-zero
              value, the PowerPC htab (see kernel file
              Documentation/powerpc/ppc_htab.txt) is pruned each time the
              system hits the idle loop.

              The file l2cr (PowerPC only) contains a flag that controls the
              L2 cache of G3 processor boards. If 0, the cache is disabled.
              Enabled if nonzero.

              The file modprobe is described by the kernel source file
              Documentation/kmod.txt.

              The file msgmax is a system-wide limit specifying the maximum
              number of bytes in a single message written on a System V
              message queue.

              The file msgmni defines the system-wide limit on the number of
              message queue identifiers.  (This file is only present in Linux
              2.4 onwards.)

              The file msgmnb is a system-wide paramter used to initialise the
              msg_qbytes setting for subsequenly created message queues.  The
              msg_qbytes setting specifies the maximum number of bytes that
              may be written to the message queue.

              The files ostype and osrelease give substrings of
              /proc/version.

              The files overflowgid and  overflowuid duplicate the files
              /proc/sys/fs/overflowgid and /proc/sys/fs/overflowuid.

              The file panic gives read/write access to the kernel variable
              panic_timeout.  If this is zero, the kernel will loop on a
              panic; if nonzero it indicates that the kernel should autoreboot
              after this number of seconds.  When you use the software
              watchdog device driver, the recommended setting is 60.

              The file powersave-nap (PowerPC only) contains a flag.  If set,
              Linux-PPC will use the 'nap' mode of powersaving, otherwise the
              'doze' mode will be used.

              The four values in the file printk are console_loglevel,
              default_message_loglevel, minimum_console_level and
              default_console_loglevel.  These values influence printk()
              behavior when printing or logging error messages. See syslog(2)
              for more info on the different loglevels.  Messages with a
              higher priority than console_loglevel will be printed to the
              console.  Messages without an explicit priority will be printed
              with priority default_message_level.  minimum_console_loglevel
              is the minimum (highest) value to which console_loglevel can be
              set.  default_console_loglevel is the default value for
              console_loglevel.

              The directory random contains various parameters controlling the
              operation of the file /dev/random.

              The file real-root-dev is documented in the kernel source file
              Documentation/initrd.txt.

              The file reboot-cmd (Sparc only)  seems to be a way to give an
              argument to the SPARC ROM/Flash boot loader. Maybe to tell it
              what to do after rebooting?

              The file rtsig-max can be used to tune the maximum number of
              POSIX realtime (queued) signals that can be outstanding in the
              system.

              The file rtsig-nr shows the number POSIX realtime signals
              currently queued.

              The file sem (available in Linux 2.4 onwards) contains 4 numbers
              defining limits for System V IPC semaphores.  These fields are,
              in order:

              SEMMSL  The maximum semaphores per semaphore set.

              SEMMNS  A system-wide limit on the number of semaphores in all
                      semaphore sets.

              SEMOPM  The maximum number of operations that may be specified
                      in a semop(2) call.

              SEMNI   A system-wide limit on the maximum number of semaphore
                      identifiers.

              The file sg-big-buff shows the size of the generic SCSI device
              (sg) buffer.  You can't tune it just yet, but you could change
              it on compile time by editing include/scsi/sg.h and changing the
              value of SG_BIG_BUFF.  However, there shouldn't be any reason to
              change this value.

              The file shmall contains the system-wide limit on the total
              number of pages of System V shared memory.

              The file shmmax can be used to query and set the run time limit
              on the maximum (System V IPC) shared memory segment size that
              can be created.  Shared memory segments up to 1Gb are now
              supported in the kernel.  This value defaults to SHMMAX.

              The file shmmni (available in Linux 2.4 and onwards) specifies
              the system-wide maximum number of System V shared memory
              segments that can be created.

              The file version contains a string like:

              #5 Wed Feb 25 21:49:24 MET 1998.TP

              The '#5' means that this is the fifth kernel built from this
              source base and the date behind it indicates the time the kernel
              was built.

              The file zero-paged (PowerPC only)  contains a flag. When
              enabled (non-zero), Linux-PPC will pre-zero pages in the idle
              loop, possibly speeding up get_free_pages.

              The    net This directory contains networking stuff.

              proc   This directory may be empty.

              sunrpc This directory supports Sun remote procedure call for
                     network file system (NFS).  On some systems, it is not
                     present.

              vm     This directory contains files for memory management
                     tuning, buffer and cache management.

       sysvipc
              Subdirectory containing the pseudo-files msg, sem and shm.
              These files list the System V Interprocess Communication (IPC)
              objects (respectively: message queues, semaphores, and shared
              memory) that currently exist on the system, providing similar
              information to that available via ipcs(1).  These files have
              headers and are formatted (one IPC object per line) for easy
              understanding.  ipc(5) provides further background on the
              information shown by these files.

       tty    Subdirectory containing the psuedo-files and subdirectories for
              tty drivers and line disciplines.

       uptime This file contains two numbers: the uptime of the system
              (seconds), and the amount of time spent in idle process
              (seconds).

       version
              This string identifies the kernel version that is currently
              running.  It includes the contents of /proc/sys/ostype,
              /proc/sys/osrelease and /proc/sys/version.  For example:
            Linux version 1.0.9 (quinlan@phaze) #1 Sat May 14 01:51:54 EDT 1994

SEE ALSO
       cat(1), find(1), free(1), mount(1), ps(1), tr(1), uptime(1), chroot(2),
       mmap(2), readlink(2), syslog(2), slabinfo(5), hier(7), arp(8),
       dmesg(8), hdparm(8), ifconfig(8), lsmod(8), lspci(8), netstat(8),
       procinfo(8), route(8) /usr/src/linux/Documentation/filesystems/proc.txt

CONFORMS TO
       This roughly conforms to a Linux 2.4.17 kernel.  Please update this as
       necessary!

       Last updated for Linux 2.4.17.

CAVEATS
       Note that many strings (i.e., the environment and command line) are in
       the internal format, with sub-fields terminated by NUL bytes, so you
       may find that things are more readable if you use od -c or tr "\000"
       "\n" to read them.  Alternatively, echo `cat _file_` works well.

       This manual page is incomplete, possibly inaccurate, and is the kind of
       thing that needs to be updated very often.

ACKNOWLEDGEMENTS
       The material on /proc/sys/fs and /proc/sys/kernel is closely based on
       kernel source documentation files written by Rik van Riel.

                                  2002-07-13                           PROC(5)

NAME | DESCRIPTION | SEE ALSO | CONFORMS TO | CAVEATS | ACKNOWLEDGEMENTS

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