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Test Your Knowledge in Computers #34
Difficulty: Medium
When a computer is first powered on, the special type of absolute loader is known as the pre-boot loader.
True or False?
Linux & Unix Commands - Search Man Pages

pgrep(1) [xfree86 man page]

PGREP(1)							   User Commands							  PGREP(1)

NAME
pgrep, pkill - look up or signal processes based on name and other attributes SYNOPSIS
pgrep [options] pattern pkill [options] pattern DESCRIPTION
pgrep looks through the currently running processes and lists the process IDs which match the selection criteria to stdout. All the crite- ria have to match. For example, $ pgrep -u root sshd will only list the processes called sshd AND owned by root. On the other hand, $ pgrep -u root,daemon will list the processes owned by root OR daemon. pkill will send the specified signal (by default SIGTERM) to each process instead of listing them on stdout. OPTIONS
-signal --signal signal Defines the signal to send to each matched process. Either the numeric or the symbolic signal name can be used. (pkill only.) -c, --count Suppress normal output; instead print a count of matching processes. When count does not match anything, e.g. returns zero, the command will return non-zero value. -d, --delimiter delimiter Sets the string used to delimit each process ID in the output (by default a newline). (pgrep only.) -f, --full The pattern is normally only matched against the process name. When -f is set, the full command line is used. -g, --pgroup pgrp,... Only match processes in the process group IDs listed. Process group 0 is translated into pgrep's or pkill's own process group. -G, --group gid,... Only match processes whose real group ID is listed. Either the numerical or symbolical value may be used. -i, --ignore-case Match processes case-insensitively. -l, --list-name List the process name as well as the process ID. (pgrep only.) -a, --list-full List the full command line as well as the process ID. (pgrep only.) -n, --newest Select only the newest (most recently started) of the matching processes. -o, --oldest Select only the oldest (least recently started) of the matching processes. -P, --parent ppid,... Only match processes whose parent process ID is listed. -s, --session sid,... Only match processes whose process session ID is listed. Session ID 0 is translated into pgrep's or pkill's own session ID. -t, --terminal term,... Only match processes whose controlling terminal is listed. The terminal name should be specified without the "/dev/" prefix. -u, --euid euid,... Only match processes whose effective user ID is listed. Either the numerical or symbolical value may be used. -U, --uid uid,... Only match processes whose real user ID is listed. Either the numerical or symbolical value may be used. -v, --inverse Negates the matching. This option is usually used in pgrep's context. In pkill's context the short option is disabled to avoid accidental usage of the option. -w, --lightweight Shows all thread ids instead of pids in pgrep's context. In pkill's context this option is disabled. -x, --exact Only match processes whose names (or command line if -f is specified) exactly match the pattern. -F, --pidfile file Read PID's from file. This option is perhaps more useful for pkill than pgrep. -L, --logpidfile Fail if pidfile (see -F) not locked. --ns pid Match processes that belong to the same namespaces. Required to run as root to match processes from other users. See --nslist for how to limit which namespaces to match. --nslist name,... Match only the provided namespaces. Available namespaces: ipc, mnt, net, pid, user,uts. -V, --version Display version information and exit. -h, --help Display help and exit. OPERANDS
pattern Specifies an Extended Regular Expression for matching against the process names or command lines. EXAMPLES
Example 1: Find the process ID of the named daemon: $ pgrep -u root named Example 2: Make syslog reread its configuration file: $ pkill -HUP syslogd Example 3: Give detailed information on all xterm processes: $ ps -fp $(pgrep -d, -x xterm) Example 4: Make all netscape processes run nicer: $ renice +4 $(pgrep netscape) EXIT STATUS
0 One or more processes matched the criteria. 1 No processes matched. 2 Syntax error in the command line. 3 Fatal error: out of memory etc. NOTES
The process name used for matching is limited to the 15 characters present in the output of /proc/pid/stat. Use the -f option to match against the complete command line, /proc/pid/cmdline. The running pgrep or pkill process will never report itself as a match. BUGS
The options -n and -o and -v can not be combined. Let me know if you need to do this. Defunct processes are reported. SEE ALSO
ps(1), regex(7), signal(7), killall(1), skill(1), kill(1), kill(2) AUTHOR
Kjetil Torgrim Homme <kjetilho@ifi.uio.no> REPORTING BUGS
Please send bug reports to <procps@freelists.org> procps-ng March 2015 PGREP(1)

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