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cu(1C)			    Communication Commands			cu(1C)

NAME
       cu - call another UNIX system

SYNOPSIS
       cu  [-c device |	-l line]  [-s speed] [-b bits] [-h] [-n] [-t] [-d] [-o
       | -e]  [-L] [-C]	[-H]  telno | systemname [local-cmd]

DESCRIPTION
       The command cu calls up another UNIX system, a terminal,	or possibly  a
       non-UNIX	 system.  It manages an	interactive conversation with possible
       transfers of files. It is convenient to think of	cu as operating	in two
       phases. The first phase is the connection phase in which	the connection
       is established. cu then enters the conversation phase. The -d option is
       the only	one that applies to both phases.

OPTIONS
       cu  accepts many	options. The -c, -l, and -s options play a part	in se-
       lecting the medium. The remaining options are used in  configuring  the
       line.

       -b bits
	     Forces  bits to be	the number of bits processed on	the line. bits
	     is	either	7 or 8.	This allows connection	between	 systems  with
	     different character sizes.	 By default, the character size	of the
	     line is set to the	same value as the current local	terminal,  but
	     the character size	setting	is affected by LC_CTYPE	also.

       -c device
	     Forces  cu	 to  use  only	entries	in the "Type" field (the first
	     field in the /etc/uucp/Devices file) that match the  user	speci-
	     fied device, usually the name of a	local area network.

       -C    Runs  the	local-cmd specified at the end of the command line in-
	     stead of entering interactive mode. The stdin and stdout  of  the
	     command that is run refer to the remote connection.

       -d    Prints diagnostic traces.

       -e    Sets  an EVEN data	parity.	 This option designates	that EVEN par-
	     ity is to be generated for	data sent to the remote	system.

       -h    Sets communication	mode to	half-duplex.  This option emulates lo-
	     cal echo in order to support calls	to other computer systems that
	     expect terminals to be set	to half-duplex mode.

       -H    Ignores one hangup. This allows the user to remain	 in  cu	 while
	     the  remote machine disconnects and places	a call back to the lo-
	     cal machine.  This	option should be used when connecting to  sys-
	     tems  with	 callback or dialback modems. Once the callback	occurs
	     subsequent	hangups	will cause cu to terminate.  This  option  can
	     be	 specified more	than once. For more information	about dialback
	     configuration, see	remote(4) and System Administration Guide:  IP
	     Services

       -l line
	     Specifies	a  device  name	to use as the communication line. This
	     can be used to override the  search  that	would  otherwise  take
	     place  for	 the first available line having the right speed. When
	     the -l option is used without the -s option, the speed of a  line
	     is	 taken	from  the  /etc/uucp/Devices file record in which line
	     matches the second	field (the Line	field).	When the -l and	-s op-
	     tions  are	 both  used together, cu will search the /etc/uucp/De-
	     vices file	to check if the	requested speed	for the	requested line
	     is	available. If so, the connection will be made at the requested
	     speed, otherwise, an error	message	will be	printed	and  the  call
	     will  not	be made.  In the general case where a specified	device
	     is	 a  directly  connected	 asynchronous  line   (for   instance,
	     /dev/term/a),  a  telephone  number  (telno) is not required. The
	     specified device need not be in the /dev directory. If the	speci-
	     fied device is associated with an auto dialer, a telephone	number
	     must be  provided.

       -L    Goes  through  the	 login	chat   sequence	  specified   in   the
	     /etc/uucp/Systems	file.  For more	information about the chat se-
	     quence, see System	Administration Guide: IP Services

       -n    Requests user prompt for telephone	number.	 For  added  security,
	     this  option will prompt the user to provide the telephone	number
	     to	be dialed, rather than	taking it from the command line.

       -o    Sets an ODD data parity.  This option designates that ODD	parity
	     is	to be generated	for data sent to the remote system.

       -s speed
	     Specifies	the  transmission  speed (300, 1200, 2400, 4800, 9600,
	     19200, 38400). The	default	value is "Any" speed which will	depend
	     on	the order of the lines in the /etc/uucp/Devices	file.

       -t    Dials  a  terminal	which has been set to auto answer. Appropriate
	     mapping of	carriage-return	to carriage-return-line-feed pairs  is
	     set.

OPERANDS
       The following operands are supported:

       telno When  using  an automatic dialler,	specifies the telephone	number
	     with equal	signs for secondary dial tone or  minus	 signs	placed
	     appropriately for delays of 4 seconds.

       systemname
	     Specifies	a  uucp	 system	 name, which can be used rather	than a
	     telephone number; in this case, cu	will obtain an appropriate di-
	     rect line or telephone number from	a system file.

USAGE
   Connection Phase
       cu  uses	 the  same mechanism that uucp(1C) does	to establish a connec-
       tion. This means	that it	will use the uucp control files	 /etc/uucp/De-
       vices  and  /etc/uucp/Systems. This gives cu the	ability	to choose from
       several different media to establish the	connection. The	possible media
       include	telephone  lines,  direct connections, and local area networks
       (LAN). The /etc/uucp/Devices file contains a list  of  media  that  are
       available  on your system. The /etc/uucp/Systems	file contains informa-
       tion for	connecting to remote systems, but it is	 not  generally	 read-
       able.

       Note: cu	determines which /etc/uucp/Systems and /etc/uucp/Devices files
       to use based upon the name used to invoke cu. In	the simple case,  this
       name  will  be  "cu", but you could also	have created a link to cu with
       another name, such as "pppcu", in which case cu would then look	for  a
       "service=pppcu"	entry  in  the	 /etc/uucp/Sysfiles  file to determine
       which /etc/uucp/Systems file to use.

       The telno or systemname parameter from the command line is used to tell
       cu  what	 system	you wish to connect to.	This parameter can be blank, a
       telephone number, a system name,	or a LAN specific address.

       telephone number
	     A telephone number	is a string consisting of the tone dial	 char-
	     acters (the digits	 0 through 9, *, and #)	plus the special char-
	     acters = and -. The equal sign designates a secondary  dial  tone
	     and the minus sign	creates	a  4 second delay.

       system name
	     A system name is the name of any computer that uucp can call; the
	     uuname(1C)	command	prints a list of these names.

       LAN address
	     The documentation for your	 LAN will show the  form  of  the  LAN
	     specific address.

       If  cu's	 default behavior is invoked (not using	the -c or -l options),
       cu will use the telno or	systemname parameter to	determine which	medium
       to  use.	 If  a	telephone number is specified, cu will assume that you
       wish to use a telephone line and	it will	select an automatic call  unit
       (ACU). Otherwise, cu will assume	that it	is a system name. cu will fol-
       low the uucp  calling  mechanism	 and  use  the	/etc/uucp/Systems  and
       /etc/uucp/Devices  files	to obtain the best available connection. Since
       cu will choose a	speed that is appropriate for the medium that  it  se-
       lects,  you  may	 not use the -s	option when this parameter is a	system
       name.

       The -c and -l options modify this default behavior. -c  is  most	 often
       used to select a	 LAN by	specifying a Type field	from the /etc/uucp/De-
       vices file. You must include either a telno or  systemname  value  when
       using  the  -c option. If the connection	to systemname fails, a connec-
       tion will be attempted using systemname as a  LAN specific address. The
       -l  option is used to specify a device associated with a	direct connec-
       tion. If	the connection is truly	a direct connection to the remote  ma-
       chine,  then there is no	need to	specify	a systemname. This is the only
       case where a telno or systemname	parameter is unnecessary. On the other
       hand,  there  may  be cases in which the	specified device connects to a
       dialer, so it is	valid to specify a telephone number. The -c and	-l op-
       tions should not	be specified on	the same command line.

   Conversation	Phase
       After  making  the  connection,	cu runs	as two processes. The transmit
       process reads data from the standard input and, except for lines	begin-
       ning  with  ~,  passes it to the	remote system. The receive process ac-
       cepts data from the remote system and, except for lines beginning  with
       ~,  passes  it  to  the standard	output.	Normally, an automatic DC3/DC1
       protocol	is used	to control input from the remote so the	buffer is  not
       overrun.	Lines beginning	with ~ have special meanings.

   Commands
       The transmit process interprets the following user initiated commands:

       ~.    Terminates	the conversation.

       ~!    Escapes to	an interactive shell on	the local system.

       ~!cmd...
	     Runs cmd on the local system (via sh -c).

       ~$cmd...
	     Runs cmd locally and send its output to the remote	system.

       ~%cd  Changes  the directory on the local system. Note: ~!cd will cause
	     the command to be run by a	sub-shell, probably not	what  was  in-
	     tended.

       ~%take from [to]
	     Copies  file  from	(on the	remote system) to file to on the local
	     system. If	to is omitted, the  from  argument  is	used  in  both
	     places.

       ~%put from [to]
	     Copies  file  from	(on local system) to file to on	remote system.
	     If	to is omitted, the from	argument is used in both places.

       ~~line
	     Sends the line ~ line to the remote system.

       ~%break
	     Transmits a  BREAK	to the remote system (which can	also be	speci-
	     fied as ~%b).

       ~%debug
	     Toggles  the  -d  debugging  option  on or	off (which can also be
	     specified as ~%d).

       ~t    Prints the	values of  the	termio	structure  variables  for  the
	     user's terminal (useful for debugging).

       ~l    Prints  the  values of the	termio structure variables for the re-
	     mote communication	line (useful for debugging).

       ~%ifc Toggles between DC3/DC1 input control protocol and	no input  con-
	     trol.  This  is  useful  when  the	remote system does not respond
	     properly to the DC3 and DC1 characters (can also be specified  as
	     ~%nostop).

       ~%ofc Toggles  the output flow control setting.	When enabled, outgoing
	     data may be flow controlled by the	remote host (can also be spec-
	     ified as ~%noostop).

       ~%divert
	     Allows/disallows unsolicited diversions.  That is,	diversions not
	     specified by ~%take.

       ~%old Allows/disallows old style	syntax for received diversions.

       ~%nostop
	     Same as  ~%ifc.

       The receive process normally copies data	from the remote	system to  the
       standard	 output	of the local system.  It may also direct the output to
       local files.

       The use of ~%put	requires stty(1) and cat(1) on	the  remote  side.  It
       also  requires that the current erase and kill characters on the	remote
       system be identical to these current control characters	on  the	 local
       system. Backslashes are inserted	at appropriate places.

       The  use	 of ~%take requires the	existence of echo(1) and cat(1)	on the
       remote system, and that the remote system  must	be  using  the	Bourne
       shell,  sh.  Also,  tabs	mode (see stty(1)) should be set on the	remote
       system if tabs are to be	copied without expansion to spaces.

       When cu is used on system X to connect to  system  Y  and  subsequently
       used  on	 system	 Y to connect to system	Z, commands on system Y	can be
       executed	by using ~~. Executing a tilde command reminds the user	of the
       local  system  uname. For example, uname	can be executed	on Z, X, and Y
       as follows:

       uname
       Z
       ~[X]!uname
       X
       ~~[Y]!uname
       Y

       In general, ~ causes the	command	to be executed	on  the	 original  ma-
       chine.  ~~ causes the command to	be executed on the next	machine	in the
       chain.

EXAMPLES
       Example 1: Dialling a system

       To dial a system	whose telephone	number is  9  1	 201  555  1234	 using
       1200 baud (where	dialtone is expected after the	9):

       example%	cu -s 1200 9=12015551234
       If the speed is not specified, "Any" is the default value.

       Example 2: Logging in to	a system on a direct line

       To login	to a system connected by a direct line:

       example%	cu -l /dev/term/b
       or

       example%	cu -l term/b

       Example 3: Dialling a system with specific line and speed

       To dial a system	with a specific	line and speed:

       example%	cu -s 1200 -l term/b

       Example 4: Using	a system name

       To use a	system name:

       example%	cu systemname

ENVIRONMENT VARIABLES
       See  environ(5) for descriptions	of the following environment variables
       that affect the execution of cu:	LC_CTYPE, LC_MESSAGES, and NLSPATH.

EXIT STATUS
       The following exit values are returned:

       0     Successful	completion.

       >0    An	error occurred.

FILES
       /etc/uucp/Devices
	     device file

       /etc/uucp/Sysfiles
	     system file

       /etc/uucp/Systems
	     system file

       /var/spool/locks/*
	     lock file

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE	TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWbnuu			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       cat(1),	echo(1),  stty(1),  tip(1),  uname(1),	 ct(1C),   uuname(1C),
       uucp(1C), remote(4), attributes(5), environ(5)

       System Administration Guide: IP Services

NOTES
       The  cu	utility	takes the default action upon receipt of signals, with
       the exception of:

       SIGHUP
	     Close the connection and terminate.

       SIGINT
	     Forward to	the remote system.

       SIGQUIT
	     Forward to	the remote system.

       SIGUSR1
	     Terminate the cu process without the  normal  connection  closing
	     sequence.

       The cu command does not do any integrity	checking on data it transfers.
       Data fields with	special	cu characters may not be transmitted properly.
       Depending on the	interconnection	hardware, it may be necessary to use a
       ~. to terminate the conversion, even if stty  0	has  been  used.  Non-
       printing	 characters  are  not  dependably transmitted using either the
       ~%put or	~%take commands. ~%put and ~%take cannot be used  over	multi-
       ple links.  Files must be moved one link	at a time.

       There  is  an artificial	slowing	of transmission	by cu during the ~%put
       operation so that loss of data is unlikely.   Files  transferred	 using
       ~%take  or ~%put	must contain a trailing	newline, otherwise, the	opera-
       tion will hang.	Entering a <Control-D> command usually clears the hang
       condition.

SunOS 5.9			  11 May 2001				cu(1C)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | USAGE | EXAMPLES | ENVIRONMENT VARIABLES | EXIT STATUS | FILES | ATTRIBUTES | SEE ALSO | NOTES

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