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System User's Guide: Communications and Networks

Exchanging Commands Between Local and Remote Systems

The Basic Networking Utilities (BNU) enable users to exchange commands between local and remote systems. The uux command runs commands on a remote system. The uupoll command controls the timing for command execution.

Using the uux Command

The uux command requests execution of a command on a remote system.

The uux command does not execute the commands on the remote system. The uux command prepares the necessary control and data files in /var/spool/uucp. The uucico program is invoked to do the transfer. After the transfer is complete, the remote system's uucico creates an execute file in its spool directory.

When the two uucico programs agree to hang up, the uuxt daemon scans the spool directory for outstanding execution requests. The uuxt daemon checks permissions and checks to see if additional information is needed. It then forks a command to do what was requested.

Note: You can use the uux command on any system configured to run a specified command. However, policies at some sites might restrict the use of certain commands for security reasons. Some sites, for example, might only permit execution of the mail command.

After the files are received on the remote system, the uuxqt daemon runs the specified command on that system. The uuxqt daemon periodically scans the remote system's public spool directory for files received in uux transmissions. The uuxqt daemon checks that data to be accessed by the sent files is present on the remote system. It also verifies that the sending system has permission to access the data. The uuxqt daemon then either executes the command or notifies the sending system that the command did not run.

For a demonstration of how the uux command can be applied, see How to Transfer a File from Your Local System to a Remote System for Printing (How to Transfer a File to a Remote System for Printing).

Using the uupoll Command

The uupoll command starts the transmission of jobs stored in the local system's public spooling directory.

The uupoll command creates a null job in the public directory for the remote system, and starts the uucico daemon. This forces the uucico daemon to immediately contact the remote system and transfer any queued jobs.

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