Ubuntu Manpage: uux - remote command execution

NAME

       uux - remote command execution

SYNOPSIS

       uux [-np] command-string

       uux [-jnp] command-string

DESCRIPTION

The uux utility shall gather zero or more files from various systems, execute a shell pipeline (see Shell
Commands ) on a specified system, and then send the standard output of the command to a file on a
specified system. Only the first command of a pipeline can have a system-name! prefix. All other commands
in the pipeline shall be executed on the system of the first command.

The following restrictions are applicable to the shell pipeline processed by uux:

* In gathering files from different systems, pathname expansion shall not be performed by uux. Thus, a
request such as:

uux "c99 remsys!~/*.c"

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

* The redirection operators ">>" , "<<" , ">|" , and ">&" shall not be accepted. Any use of these
redirection operators shall cause this utility to write an error message describing the problem and
exit with a non-zero exit status.

* The reserved word ! cannot be used at the head of the pipeline to modify the exit status. (See the
command-string operand description below.)

* Alias substitution shall not be performed.

A filename can be specified as for uucp; it can be an absolute pathname, a pathname preceded by ~ name
(which is replaced by the corresponding login directory), a pathname specified as ~/ dest ( dest is
prefixed by the public directory called PUBDIR; the actual location of PUBDIR is implementation-defined),
or a simple filename (which is prefixed by uux with the current directory). See uucp for the details.

The execution of commands on remote systems shall take place in an execution directory known to the uucp
system. All files required for the execution shall be put into this directory unless they already reside
on that machine. Therefore, the application shall ensure that non-local filenames (without path or
machine reference) are unique within the uux request.

The uux utility shall attempt to get all files to the execution system. For files that are output files,
the application shall ensure that the filename is escaped using parentheses.

The remote system shall notify the user by mail if the requested command on the remote system was
disallowed or the files were not accessible. This notification can be turned off by the -n option.

Typical implementations of this utility require a communications line configured to use the Base
Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface, but other
communications means may be used. On systems where there are no available communications means (either
temporarily or permanently), this utility shall write an error message describing the problem and exit
with a non-zero exit status.

The uux utility cannot guarantee support for all character encodings in all circumstances. For example,
transmission data may be restricted to 7 bits by the underlying network, 8-bit data and filenames need
not be portable to non-internationalized systems, and so on. Under these circumstances, it is recommended
that only characters defined in the ISO/IEC 646:1991 standard International Reference Version (equivalent
to ASCII) 7-bit range of characters be used and that only characters defined in the portable filename
character set be used for naming files.

OPTIONS

       The  uux  utility  shall  conform  to  the Base Definitions volume of IEEE Std 1003.1-2001, Section 12.2,
       Utility Syntax Guidelines.

       The following options shall be supported:

       -p     Make the standard input to uux the standard input to the command-string.

       -j     Write the job identification string to standard output. This job identification  can  be  used  by
              uustat to obtain the status or terminate a job.

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

OPERANDS

       The following operand shall be supported:

       command-string

              A  string  made  up  of one or more arguments that are similar to normal command arguments, except
              that the command and any filenames can be prefixed by system-name!. A null  system-name  shall  be
              interpreted as the local system.

STDIN

       The  standard  input  shall  not  be  used  unless the '-' or -p option is specified; in those cases, the
       standard input shall be made the standard input of the command-string.

INPUT FILES

       Input files shall be selected according to the contents of command-string.

ENVIRONMENT VARIABLES

       The following environment variables shall affect the execution of uux:

       LANG   Provide a default value for the internationalization variables that are unset or  null.  (See  the
              Base  Definitions  volume of IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for
              the  precedence  of  internationalization  variables  used  to  determine  the  values  of  locale
              categories.)

       LC_ALL If  set  to  a  non-empty  string value, override the values of all the other internationalization
              variables.

       LC_CTYPE
              Determine the locale for the interpretation of sequences of bytes of text data as characters  (for
              example, single-byte as opposed to multi-byte characters in arguments).

       LC_MESSAGES
              Determine  the locale that should be used to affect the format and contents of diagnostic messages
              written to standard error.

       NLSPATH
              Determine the location of message catalogs for the processing of LC_MESSAGES .

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       The standard output shall not be used  unless  the  -j  option  is  specified;  in  that  case,  the  job
       identification string shall be written to standard output in the following format:

              "%s\n", <jobid>

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       Output files shall be created or written, or both, according to the contents of command-string.

       If  -n  is  not  used,  mail files shall be modified following any command or file-access failures on the
       remote system.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

        0     Successful completion.

       >0     An error occurred.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       Note that, for security reasons, many installations limit the list of commands executable on behalf of an
       incoming request from uux. Many sites permit little more than the receipt of mail via uux.

       Any  characters special to the command interpreter should be quoted either by quoting the entire command-
       string or quoting the special characters as individual arguments.

       As noted in uucp, shell pattern matching notation characters appearing in pathnames are expanded  on  the
       appropriate  local  system. This is done under the control of local settings of LC_COLLATE and LC_CTYPE .
       Thus, care should be taken when using bracketed filename patterns, as collation and typing rules may vary
       from one system to another. Also be aware that certain types of expression (that is, equivalence classes,
       character classes, and collating symbols) need not be supported on non-internationalized systems.

EXAMPLES

        1. The following command gets file1 from system a and file2 from system b, executes diff  on  the  local
           system,  and puts the results in file.diff in the local PUBDIR directory. ( PUBDIR is the uucp public
           directory on the local system.)

           uux "!diff a!/usr/file1 b!/a4/file2 >!~/file.diff"

        2. The following command fails because uux places all files copied to  a  system  in  the  same  working
           directory.  Although  the  files xyz are from two different systems, their filenames are the same and
           conflict.

           uux "!diff a!/usr1/xyz b!/usr2/xyz >!~/xyz.diff"

        3. The following command succeeds (assuming diff is permitted on system a) because  the  file  local  to
           system  a  is  not  copied  to  the working directory, and hence does not conflict with the file from
           system c.

           uux "a!diff a!/usr/xyz c!/usr/xyz >!~/xyz.diff"

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc  and  The  Open Group. In the event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .