I used to wonder how can I find all the PID’s used by a specific user in the system or an application. This is a long time question in my mind. I used to try all sorts of commands to find what process is running by a service/user. The workaround commands which I used are as follows.
1.#ps -ef 2.#top
But none of these tools gives a number of processes run for an Application or a User.
That’s where I come across one wonderful command. To serve the purpose there is a command in Linux called pgrep(process grep). The grep command greps content in a file whereas pgrep greps process from proc file system. Let us have a look at pgrep usage.
Syntax of pgrep command in Linux
Example1: Suppose we want to find what PID’s are used by firefox application.
# pgrep firefox
Example2: Suppose you need process run by a user then use below command
#pgrep -u user-ID
#pgrep -u 1000
Where 1000 is the user ID for a user
1602 1621 1651 1654 1655 1660 1663 1669 1673 1678 1685 1686 1688
Example3: The above output just gives PID’s one each in the line. How about giving process details as well? We can use -a to list the process details as well.
root@linuxnix:~# pgrep nginx -a 30615 nginx: master process /usr/sbin/nginx -g daemon on; master_process on; 30618 nginx: worker process
Example4: To list only PID’s but with different separator other than the new line, we can use -d to specify the delimiter.
root@linuxnix:~# pgrep -U 0 -d, 1,2,3,5,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,28,29,30,31,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,68,81,82,121,122,123,124,125,126,127,128,129,130,131,485,516,537,538,618,626,629,642,646,648,650,651,656,665,697,748,771,1274,1275,1280,1283,1297,1307,1310,1312,1342,1367,1407,1413,1534,1691,2889,4044,4046,4051,4105,4121,4131,4141,4174,4290,4332,23962,23963,30615,30629,31150
Example5: If we just want to list a number of the process used by a user instead of listing all the PID we can use count option.
root@linuxnix:~# pgrep -U 0 -c 103
And There are many options for this command explore your self by using man pages.
In our next post, we will see about other process related command called pmap.
Latest posts by Surendra Anne (see all)
- FREE: JOIN OUR DEVOPS TELEGRAM GROUPS - August 2, 2019
- Review: Whizlabs Practice Tests for AWS Certified Solutions Architect Professional (CSAP) - August 27, 2018
- How to use ohai/chef-shell to get node attributes - July 19, 2018
- wget download a file to a directory in Linux/Unix - June 4, 2018
- GIT: How to compare two GIT branches? - June 3, 2018