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
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
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.
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
The following environment variables shall affect the execution of uux:
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.)
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 LC_MESSAGES.
Output files shall be created or written, or both, according to the contents of
If -n is not used, mail files shall be modified following any command or
file-access failures on the remote system.
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
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
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.)
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
uux "!diff a!/usr1/xyz b!/usr2/xyz >!~/xyz.diff"
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.
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