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 .