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CU(1)			FreeBSD	General	Commands Manual			 CU(1)

     cu	-- call	UNIX

     cu	[-ehot]	[-a acu] [-l line] [-s speed | -speed] [phone-number]

     The cu utility establishes	a full-duplex connection to another machine,
     giving the	appearance of being logged in directly on the remote CPU.  It
     goes without saying that you must have a login on the machine (or equiva-
     lent) to which you	wish to	connect.

     The options are as	follows:

     -a	acu  Set the acu.

     -e	     Use even parity.  If both -e and -o are given, then no parity is
	     used (the default).

     -h	     Echo characters locally (half-duplex mode).

     -l	line
	     Specify the line to use.  Either of the forms like	cuau0 or
	     /dev/cuau0	are permitted.

     -o	     Use odd parity.  If both -e and -o	are given, then	no parity is
	     used (the default).

     -s	speed |	-speed
	     Set the speed of the connection.  The default is 9600.

     -t	     Connect via a hard-wired connection to a host on a	dial-up	line.

     Typed characters are normally transmitted directly	to the remote machine
     (which does the echoing as	well).	A tilde	(`~') appearing	as the first
     character of a line is an escape signal; the following are	recognized:

     ~^D or ~.
	     Drop the connection and exit.  Only the connection	is dropped -
	     the login session is not terminated.

     ~c	[name]
	     Change directory to name (no argument implies change to home di-

     ~!	     Escape to a shell (exiting	the shell will return to cu).

     ~>	     Copy file from local to remote.  The cu utility prompts for the
	     name of a local file to transmit.

     ~<	     Copy file from remote to local.  The cu utility prompts first for
	     the name of the file to be	sent, then for a command to be exe-
	     cuted on the remote machine.

     ~p	from [to]
	     Send a file to a remote UNIX host.	 This command causes the re-
	     mote UNIX system to run the following command string, sending it
	     the from file:

		   stty	-echo; cat > 'to'; stty	echo

	     If	the to file is not specified, the from file name is used.
	     This command is actually a	UNIX specific version of the ~>	com-

     ~t	from [to]
	     Take a file from a	remote UNIX host.  As in the ~p	command, the
	     to	file defaults to the from file name if it is not specified.
	     The remote	host executes the following command string to send the
	     file to cu:

		   cat 'from'; echo '' | tr '\012' '\01'

     ~|	     Pipe the output from a remote command to a	local UNIX process.
	     The command string	sent to	the local UNIX system is processed by
	     the shell.

     ~$	     Pipe the output from a local UNIX process to the remote host.
	     The command string	sent to	the local UNIX system is processed by
	     the shell.

     ~C	     Fork a child process on the local system to perform special pro-
	     tocols such as XMODEM.  The child program will be run with	the
	     following arrangement of file descriptors:

		   0 <-> remote	tty in
		   1 <-> remote	tty out
		   2 <-> local tty stderr

     ~#	     Send a BREAK to the remote	system.	 For systems which do not sup-
	     port the necessary	ioctl()	call, the break	is simulated by	a se-
	     quence of line speed changes and DEL characters.

     ~s	     Set a variable (see the discussion	below).

     ~v	     List all variables	and their values (if set).

     ~^Z     Stop cu (only available with job control).

     ~^Y     Stop only the "local side"	of cu (only available with job con-
	     trol); the	"remote	side" of cu, the side that displays output
	     from the remote host, is left running.

     ~?	     Get a summary of the tilde	escapes.

     When cu prompts for an argument, for example during setup of a file
     transfer, the line	typed may be edited with the standard erase and	kill
     characters.  A null line in response to a prompt, or an interrupt,	will
     abort the dialogue	and return the user to the remote machine.

     The cu utility guards against multiple users connecting to	a remote sys-
     tem by opening modems and terminal	lines with exclusive access, and by
     honoring the locking protocol used	by uucico(8) (ports/net/freebsd-uucp).

     During file transfers cu provides a running count of the number of	lines
     transferred.  When	using the ~> and ~< commands, the eofread and eofwrite
     variables are used	to recognize end-of-file when reading, and specify
     end-of-file when writing (see below).  File transfers normally depend on
     hardwareflow or tandem mode for flow control.  If the remote system does
     not support hardwareflow or tandem	mode, echocheck	may be set to indicate
     that cu should synchronize	with the remote	system on the echo of each
     transmitted character.

     When cu must dial a phone number to connect to a system, it will print
     various messages indicating its actions.  The cu utility supports a vari-
     ety of auto-call units and	modems with the	at capability in system	de-

     Support for Ventel	212+ (ventel), Hayes AT-style (hayes), USRobotics
     Courier (courier),	Telebit	T3000 (t3000) and Racal-Vadic 831 (vadic)
     units is enabled by default.

     Support for Bizcomp 1031[fw] (biz31[fw]), Bizcomp 1022[fw]	(biz22[fw]),
     DEC DF0[23]-AC (df0[23]), DEC DN-11 (dn11)	and Racal-Vadic	3451 (v3451)
     units can be added	by recompiling cu with the appropriate defines.

     Note that if support for both the Racal-Vadic 831 and 3451	is enabled,
     they are referred to as the v831 and v3451, respectively.	If only	one of
     the two is	supported, it is referred to as	vadic.

     The cu utility maintains a	set of variables which control its operation.
     Some of these variables are read-only to normal users (root is allowed to
     change anything of	interest).  Variables may be displayed and set through
     the ~s escape.  The syntax	for variables is patterned after vi(1) and
     Mail(1).  Supplying "all" as an argument to the set command displays all
     variables readable	by the user.  Alternatively, the user may request dis-
     play of a particular variable by attaching	a `?' to the end.  For exam-
     ple, "escape?" displays the current escape	character.

     Variables are numeric, string, character, or boolean values.  Boolean
     variables are set merely by specifying their name;	they may be reset by
     prepending	a `!' to the name.  Other variable types are set by concate-
     nating an `=' and the value.  The entire assignment must not have any
     blanks in it.  A single set command may be	used to	interrogate as well as
     set a number of variables.	 Certain common	variables have abbreviations.
     The following is a	list of	common variables, their	abbreviations, and
     their default values:

	     (num) The baud rate at which the connection was established; ab-
	     breviated ba.

	     (bool) Discard unprintable	characters when	a session is being
	     scripted; abbreviated be.

	     (num) When	dialing	a phone	number,	the time (in seconds) to wait
	     for a connection to be established; abbreviated dial.

	     (bool) Synchronize	with the remote	host during file transfer by
	     waiting for the echo of the last character	transmitted; default
	     is	off.

	     (str) The set of characters which signify an end-of-transmission
	     during a ~< file transfer command;	abbreviated eofr.

	     (str) The string sent to indicate end-of-transmission during a ~>
	     file transfer command; abbreviated	eofw.

     eol     (str) The set of characters which indicate	an end-of-line.	 The
	     cu	utility	will recognize escape characters only after an end-of-

     escape  (char) The	command	prefix (escape)	character; abbreviated es; de-
	     fault value is `~'.

	     (str) The set of characters which should not be discarded due to
	     the beautification	switch;	abbreviated ex;	default	value is

     force   (char) The	character used to force	literal	data transmission; ab-
	     breviated fo; default value is `^P'.

	     (num) The amount of data (in bytes) to buffer between file	system
	     writes when receiving files; abbreviated fr.

	     (bool) Whether hardware flow control (CRTSCTS) is enabled for the
	     connection; abbreviated hf; default value is off.

     host    (str) The name of the host	to which you are connected; abbrevi-
	     ated ho.

	     (num) The line discipline to use; abbreviated ld.

     prompt  (char) The	character which	indicates an end-of-line on the	remote
	     host; abbreviated pr; default value is `\n'.  This	value is used
	     to	synchronize during data	transfers.  The	count of lines trans-
	     ferred during a file transfer command is based on receipt of this

     raise   (bool) Upper case mapping mode; abbreviated ra; default value is
	     off.  When	this mode is enabled, all lowercase letters will be
	     mapped to uppercase by cu for transmission	to the remote machine.

	     (char) The	input character	used to	toggle uppercase mapping mode;
	     abbreviated rc; not set by	default.

     record  (str) The name of the file	in which a session script is recorded;
	     abbreviated rec.

     script  (bool) Session scripting mode; abbreviated	sc; default is off.
	     When script is true, cu will record everything transmitted	by the
	     remote machine in the script record file specified	in record.  If
	     the beautify switch is on,	only printable ASCII characters	will
	     be	included in the	script file (those characters between 040 and
	     0177).  The variable exceptions is	used to	indicate characters
	     which are an exception to the normal beautification rules.

	     (bool) Expand tabs	to spaces during file transfers; abbreviated
	     tab; default value	is false.  Each	tab is expanded	to 8 spaces.

     tandem  (bool) Use	XON/XOFF flow control to throttle data from the	remote
	     host; abbreviated ta.  The	default	value is true.

	     (bool) Verbose mode; abbreviated verb; default is true.  When
	     verbose mode is enabled, cu prints	messages while dialing,	shows
	     the current number	of lines transferred during a file transfer
	     operations, and more.

     HOME    The home directory	to use for the ~c command.

     SHELL   The name of the shell to use for the ~! command; default value is

     /var/log/aculog	     line access log
     /var/spool/lock/LCK..*  lock file to avoid	conflicts with uucp(1)

     Connect to	the first USB serial port at the speed of 115200 baud:

	   cu -s 115200	-l /dev/cuaU0


     The cu command appeared in	4.2BSD.

     The full set of variables is undocumented and should, probably, be	pared

FreeBSD	13.0			April 22, 2017			  FreeBSD 13.0


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