Linux / UNIX: Find out or determine if process pid is running

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How do I find out my process is running on a Unix-like operating systems? How do I get the pid number for particular process on a Linux operating systems using bash shell?

A PID is an acronym for process identification number on a Linux or Unix-like operating system. A PID is automatically assigned to each process when it is created. A process is nothing but running instance of a program and each process has a unique PID on a Unix-like system.

The easiest way to find out if process is running is run ps aux command and grep process name. If you got output along with process name/pid, your process is running.

Task: Find out process pid

Simply use ps command as follows:
ps aux | grep {process-name}

For example find out if mysqld process (mysqld pid) is running or not:
$ ps aux | grep mysqld
Sample outputs:

mysql    28290  1.1  2.7 340496 56812 ?        Sl   Jul31 348:27 /usr/libexec/mysqld --defaults-file=/etc/my.cnf --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/mysqld.pid --skip-locking --socket=/var/lib/mysql/mysql.sock

Find the process ID of a running program using pidof

pidof command finds the process id’s (pids) of the named programs. It prints those id’s on screen. This program is on some systems used in run level change scripts, especially when the system has a System-V like rc structure. In that case these scripts are located in /etc/rc?.d, where ? is the runlevel. If the system has a start-stop-daemon (8) program that should be used instead.
# pidof mysqld
Sample outputs:

28290

Find PID using pgrep command

The pgrep command searches the running system and shows the process IDs of all processes that match the given criteria. The syntax is:
pgrep {processNameHere}
pgrep firefox
pgrep httpd
pgrep nginx

Sample outputs:

4241

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

19 comment

  1. hay man you can use pgrep also know?
    why ps -aux | grep process name?
    u can use pgrep like this
    pgrep process name
    pgrep httpd
    pgrep named
    pgrep firefox
    etc
    if any special about your command just give me info related to it

  2. Hi .

    I have a probleam . when i start mysql it is showing MySQL manager or server PID file could not be found! [FAILED] . Starting MySQL/etc/init.d/mysql: line 159: kill: (5984) – No such process .how to solve the probleam. if any one know plz help me

  3. when i reconfigure (squid -k reconfigure) squid i got error.
    like this
    squid: ERROR: Could not send signal 1 to process 6471: (3) No such process
    how i can remove this error please help me.

    Thanks in advance

  4. Bear in mind that the command itself can show up in the results. For instance:

    [email protected] ~ $ ps aux | grep ntp
    root     20417  0.0  0.0   4408  1316 ?        Ss   17:30   0:00 /usr/sbin/ntpd -p /var/run/ntpd.pid
    mikkel   20429  0.0  0.0   2064   572 pts/0    S+   17:30   0:00 grep --colour=auto ntp

    If you only see the grep command listed, that means the named command is not running.

  5. Hii,
    im facing one problem with pgrep command
    I want to display the PID of process with greping on process name..im using this command for that:
    pgrep -lfu $UID | grep -i AddUser | grep -v grep | grep bash | tr -s ” ” | cut -d ” ” -f1
    but since the path of process AddUser is too long..the output of pgrep does not shows the fullname of process instead it crops the process name and displays only first 3 chars…Any idea to avoid cropping of process name

  6. Hi All I want to know how many jobs are running on a particular server. So can anyone help me providing the command so that I could able to check how many jobs are running in the server and log status as well

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