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UUX(P) POSIX Programmer's Manual UUX(P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
uux - remote command execution
uux [-np] command-string
uux [-jnp] command-string
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 speci-
fied 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 pro-
cessed 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
* Alias substitution shall not be performed.
A filename can be specified as for uucp; it can be an absolute path-
name, a pathname preceded by ~ name (which is replaced by the corre-
sponding 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 pre-
fixed by uux with the current directory). See uucp for the details.
The execution of commands on remote systems shall take place in an exe-
cution 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
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 com-
mand on the remote system was disallowed or the files were not accessi-
ble. 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 sta-
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 cir-
cumstances, 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
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 com-
-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.
The following operand shall be supported:
A string made up of one or more arguments that are similar to
normal command arguments, except that the command and any file-
names can be prefixed by system-name!. A null system-name shall
be interpreted as the local system.
The standard input shall not be used unless the '-' or -p option is
specified; in those cases, the standard input shall be made the stan-
dard input of the command-string.
Input files shall be selected according to the contents of command-
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 Vari-
ables 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.
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).
Determine the locale that should be used to affect the format
and contents of diagnostic messages written to standard error.
Determine the location of message catalogs for the processing of
The standard output shall not be used unless the -j option is speci-
fied; in that case, the job identification string shall be written to
standard output in the following format:
The standard error shall be used only for diagnostic messages.
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.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
The following sections are informative.
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 colla-
tion 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-
1. The following command gets file1 from system a and file2 from sys-
tem b, executes diff on the local system, and puts the results in
file.diff in the local PUBDIR directory. ( PUBDIR is the uucp pub-
lic 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 con-
uux "!diff a!/usr1/xyz b!/usr2/xyz >!~/xyz.diff"
3. The following command succeeds (assuming diff is permitted on sys-
tem a) because the file local to system a is not copied to the
working directory, and hence does not conflict with the file from
uux "a!diff a!/usr/xyz c!/usr/xyz >!~/xyz.diff"
Shell Command Language , uucp , uuencode , uustat
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 .
IEEE/The Open Group 2003 UUX(P)
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