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System Administration Guide: Network Services
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UUCP Administrative Files

The UUCP administrative files are described next. These files are created in spool directories to lock devices, hold temporary data, or keep information about remote transfers or executions.

  • Temporary data files (TM) – These data files are created by UUCP processes under the spool directory /var/spool/uucp/x when a file is received from another computer. The directory x has the same name as the remote computer that is sending the file. The names of the temporary data files have the following format:

    pid is a process ID and ddd is a sequential three-digit number that starts at 0.

    When the entire file is received, the file is moved to the path name that is specified in the C.sysnxxxx file (discussed subsequently) that caused the transmission. If processing is abnormally terminated, the file can remain in the x directory. These files should be automatically removed by uucleanup.

  • Lock files (LCK) – Lock files are created in the /var/spool/locks directory for each device in use. Lock files prevent duplicate conversations and multiple attempts to use the same calling device. The following table shows the different types of UUCP lock files.

Table 26-6 UUCP Lock Files

File Name



sys represents the name of the computer that is using the file

dev represents the name of a device that is using the file


LOG represents a locked UUCP log file

These files can remain in the spool directory if the communications link is unexpectedly dropped, such as when a computer crashes. The lock file is ignored (removed) after the parent process is no longer active. The lock file contains the process ID of the process that created the lock.

  • Work file (C.) – Work files are created in a spool directory when work, such as file transfers or remote command executions, has been queued for a remote computer. The names of work files have the following format:


    sys is the name of the remote computer, n is the ASCII character that represents the grade (priority) of the work, and xxxx is the four-digit job sequence number that is assigned by UUCP. Work files contain the following information:

    • Full path name of the file to be sent or be requested.

    • Full path name of the destination or user or file name.

    • User login name.

    • List of options.

    • Name of associated data files in the spool directory. If the uucp -C or uuto -p option was specified, a dummy name (D.0) is used.

    • Mode bits of the source file.

    • Remote user's login name to be notified on completion of the transfer.

  • Data file(D.) – Data files are created when you specify on the command line to copy the source file to the spool directory. The names of data files have the following format:

    D.systmxxxxyyysystm is the first five characters in the name of the remote computer. xxxx is a four-digit job sequence number assigned by uucp. The four-digit job sequence number can be followed by a subsequent number. yyy is used when several D. files are created for a work (C.) file.

  • X. (execute file) – Execute files are created in the spool directory prior to remote command executions. The names of execute files have the following format:


    sys is the name of the remote computer. n is the character that represents the grade (priority) of the work. xxxx is a four-digit sequence number that is assigned by UUCP. Execute files contain the following information:

    • Requester's login and computer name

    • Names of files that are required for execution

    • Input to be used as the standard input to the command string

    • Computer and file name to receive standard output from the command execution

    • Command string

    • Option lines for return status requests

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