Information Technology Reference
In-Depth Information
The other command-line argument is -l , which includes the name of the
program with the PIDs of matched processes. The following listing shows
the use of the -l command-line argument:
$ pgrep -l -u ambro
781 xterm
782 sh
910 telnet
913 sh
$
The pkill command is similar to the pgrep command, but instead of dis-
playing information on matched processes, the matched processes are termi-
nated using the SIGTERM (15) signal.
All the common pgrep and pkill command-line arguments listed in Table
5.4 are supported, allowing processes to be selected on the basis of regular
expression pattern matching and/or various IDs. In addition, the pkill
command supports a command-line argument to specify a signal to be used
instead of SIGTERM . This command-line argument is the minus sign followed
by a symbolic name (not including the SIG prefix) or the signal number. The
following listing shows the use of the SIGKILL signal to terminate all process-
es associated with the ambro user account:
# pkill -KILL -u ambro
#
Be familiar with the signals used to terminate processes. Know how to specify using
both signal numbers and names along with the default signals used by the kill and
pkill commands.
Scheduling Processes
Two commands are available for scheduling automatic execution of processes:
cron(1M) and at(1) .
The cron Command
The cron command is a daemon started during system boot. It is responsible
for executing commands at a future time and perhaps periodically on a
scheduled basis. The commands to be executed are specified in a standard-
ized tabular format and stored in files referred to as crontab files . These files
are located in the /var/spool/cron/crontabs directory.
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