UUX(1C) Communication Commands UUX(1C)


uux - UNIX-to-UNIX system command execution


uux [-] [-bcCjnprz] [-a name] [-g grade]
[-s filename] [-x debug_level] command-string


The uux utility will gather zero or more files from various systems,
execute a command on a specified system and then send standard output to
a file on a specified system.

Note: For security reasons, most installations limit the list of
commands executable on behalf of an incoming request from uux, permitting
only the receipt of mail (see mail(1)). (Remote execution permissions are
defined in /etc/uucp/Permissions.)

The command-string is made up of one or more arguments that look like a
shell command line, except that the command and file names may be
prefixed by system-name!. A null system-name is interpreted as the local

File names may be one of the following:

o An absolute path name.

o A path name preceded by ~xxx, where xxx is a login name on the
specified system and is replaced by that user's login

Anything else is prefixed by the current directory.

As an example, the command:

example% uux "!diff sys1!/home/dan/filename1 \
sys2!/a4/dan/filename2 > !~/dan/filename.diff"

will get the filename1 and filename2 files from the sys1 and sys2
machines, execute a diff(1) command and put the results in filename.diff
in the local PUBDIR/dan/ directory. PUBDIR is a public directory defined
in the uucp source. By default, this directory is /var/spool/uucppublic.

Any special shell characters (such as < > ; |) should be quoted either by
quoting the entire command-string, or quoting the special characters as
individual arguments. The redirection operators >>, <<, >|, and >&
cannot be used.

uux will attempt to get all appropriate files to the specified system
where they will be processed. For files that are output files, the file
name must be escaped using parentheses. For example, the command:

example% uux "a!cut -f1 b!/usr/filename > c!/usr/filename"

gets /usr/filename from system b and sends it to system a, performs a cut
command on that file and sends the result of the cut command to system c.

uux will notify you if the requested command on the remote system was
disallowed. This notification can be turned off by the -n option. The
response comes by remote mail from the remote machine.


The following options are supported:

The standard input to uux is made the standard input to
the command-string.

-a name
Uses name as the user job identification replacing the
initiator user-id. (Notification will be returned to
user-id name.)

Returns whatever standard input was provided to the uux
command if the exit status is non-zero.

Does not copy local file to the spool directory for
transfer to the remote machine (default).

Forces the copy of local files to the spool directory
for transfer.

-g grade
grade can be either a single letter, number, or a
string of alphanumeric characters defining a service
grade. The uuglist(1C) command determines whether it is
appropriate to use the single letter, number, or a
string of alphanumeric characters as a service grade.
The output from the uuglist command will be a list of
service grades that are available or a message that
says to use a single letter or number as a grade of

Outputs the jobid string on the standard output which
is the job identification. This job identification can
be used by uustat(1C) to obtain the status or
terminate a job.

Does not notify the user if the command fails.

Same as -. The standard input to uux is made the
standard input to the command-string.

Does not start the file transfer, but just queues the

-s filename
Reports status of the transfer in filename. This option
is accepted for compatibility, but it is ignored
because it is insecure.

-x debug_level
Produces debugging output on the standard output.
debug_level is a number between 0 and 9. As debug_level
increases to 9, more detailed debugging information is

Sends success notification to the user.


See environ(7) for descriptions of the following environment variables
that affect the execution of uux: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,


The following exit values are returned:

Successful completion.

An error occurred.


other data and programs

remote execution permissions

other programs

spool directories


See attributes(7) for descriptions of the following attributes:

|Interface Stability | Standard |


cut(1), mail(1), uucp(1C), uuglist(1C), uustat(1C), attributes(7),
environ(7), standards(7)


The execution of commands on remote systems takes place in an execution
directory known to the uucp system.

All files required for the execution will be put into this directory
unless they already reside on that machine. Therefore, the simple file
name (without path or machine reference) must be unique within the uux
request. The following command will NOT work:

example% uux "a!diff b!/home/dan/xyz c!/home/dan/xyz > !xyz.diff"

But the command:

example% uux "a!diff a!/home/dan/xyz c!/home/dan/xyz > !xyz.diff"

will work (if diff is a permitted command.)

Protected files and files that are in protected directories that are
owned by the requester can be sent in commands using uux. However, if the
requester is root, and the directory is not searchable by "other", the
request will fail.

The following restrictions apply to the shell pipeline processed by uux:

o In gathering files from different systems, pathname expansion
in not performed by uux. Thus, a request such as

uux "c89 remsys!~/*.c"

would attempt to copy the file named literally *.c to the
local system.

o Only the first command of a shell pipeline may have a system-
name!. All other commands are executed on the system of the
first command.

o The use of the shell metacharacter * will probably not do what
you want it to do.

o The shell tokens << and >> are not implemented.

o The redirection operators >>, <<, >|, and >& cannot be used.

o The reserved word ! cannot be used at the head of the pipeline
to modify the exit status.

o Alias substitution is not performed.

March 28, 1995 UUX(1C)