Daemons

The UUCP system has four daemons: uucico, uuxqt, uusched and in.uucpd. These daemons handle UUCP file transfers and command executions. You can also run them manually from the shell, if necessary.

• uucico - Selects the device used for the link, establishes the link to the remote computer, performs the required login sequence and permission checks, transfers data and execute files, logs results, and notifies the user by mail of transfer completions. uucico acts as the "login shell" for UUCP login accounts. When the local uucico daemon calls a remote machine, it communicates directly with the remote uucico daemon during the session.

  uucp, uuto, and uux programs execute the uucico daemon after all the required files have been created, to contact the remote computer. uusched and Uutry all execute uucico. (See the uucico(1M) man page for details.)

• uuxqt - Executes remote execution requests. It searches the spool directory for execute files (always named X.file) that have been sent from a remote computer. When an X.file file is found, uuxqt opens it to get the list of data files that are required for the execution. It then checks to see if the required data files are available and accessible. If the files are available, uuxqt checks the Permissions file to verify that it has permission to execute the requested command. The uuxqt daemon is executed by the uudemon.hour shell script, which is started by cron. (See the uuxqt(1M) man page for details.)

• uusched - Schedules the queued work in the spool directory. uusched is initially run at boot time by the uudemon.hour shell script, which is started by cron. (See the uusched(1M) man page for details.) Before starting the uucico daemon, uusched randomizes the order in which remote computers are called.

• in.uucpd - Supports UUCP connections over networks. The inetd on the remote host invokes in.uucpd whenever a UUCP connection is established. uucpd then prompts for a login name. uucico on the calling host must respond with a login name. in.uucpd then prompts for a password, unless one is not required. (See the in.uucpd(1M) man page for details.)