Content-type: text/html Man page of uux


Section: Communication Commands (1C)
Updated: 28 Mar 1995
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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 system.

File names may be one of the following:

• An absolute path name.

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

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.)

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

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

-C 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 service.

-j 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.

-n Does not notify the user if the command fails.

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

-r Does not start the file transfer, but just queues the job.

-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 given.

-z Sends success notification to the user.



See environ(5) for descriptions of the following environment variables that affect the execution of uux: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.  


The following exit values are returned:

0 Successful completion.

>0 An error occurred.



/etc/uucp/* other data and programs

/etc/uucp/Permissions remote execution permissions

/usr/lib/uucp/* other programs

/var/spool/uucp spool directories



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

Interface StabilityStandard



cut(1), mail(1), uucp(1C), uuglist(1C), uustat(1C), attributes(5), environ(5), standards(5)  


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:

• 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.

• 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.

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

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

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

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

• Alias substitution is not performed.




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Time: 02:37:49 GMT, October 02, 2010