locks - A directory that contains lock files for communication devices and
remote systems that prevent multiple attempts to use the same device or
contact a remote system
Lock files are created by the uucico daemon, the cu command, the tip com-
mand, and the uugetty command in the /var/spool/locks directory. The files
are created when the utility opens the serial line for communication.
The lock file locks the device or remote system so that another process
cannot access it while it is in use. The file name of the lock file uses
one of the following forms:
Where device_name is the name of the device (such as ttyd0) and system_name
is the name of the system (such as hera).
Normally, the process that creates a lock file will remove it when the pro-
cess has finished using the line. However, it is possible for lock files to
be left behind (for example: system crash, phone line disconnects unexpect-
edly). This situation has been accounted for and the commands that use lock
files can handle the situation and overwrite these files, if appropriate.
Lock files contains the process ID (PID) of the process that created the
lock. The lock file is a data file; to see its contents, use the following
od -d lockfile
Where lockfile is the name of the file. For example:
% od -d /var/spool/locks/LCK..ttyd0
0000000 06854 00000
In this example, the lock file (LCK..ttyd0) was created by the process with
Contains the uucico daemon and uugetty program.
/usr/bin Contains the uucp, cu, and tip programs.
Commands: cu(1), od(1), tip(1), uucp(1), uugetty(8)