uuxposix - Online in the Cloud

PROGRAM:

NAME

uux — remote command execution

SYNOPSIS

uux [−jnp] command−string

DESCRIPTION

The uux utility shall gather zero or more files from various systems, execute a shell
pipeline (see Section 2.9, 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 POSIX.1‐2008, 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 POSIX.1‐2008, Section
12.2, Utility Syntax Guidelines.

The following options shall be supported:

−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.

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

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 POSIX.1‐2008, 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

This utility is part of the UUCP Utilities option and need not be supported by all
implementations.

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.

Use uuxposix online using onworks.net services