Linux find processes by user

Linux find process by name

Procedure to find process by name on Linux

1. Open the terminal application.
2. Type the pidof command as follows to find PID for firefox process:
   pidof firefox
3. Or use the ps command along with grep command as follows:
   ps aux | grep -i firefox
4. To look up or signal processes based on name use:

pgrep firefox

Linux find process by name using pgrep command

pgrep command looks through the currently running processes and lists the process IDs which match the selection criteria to screen. All the criteria have to match. For example, will only list the processes called sshd AND owned by root user:
$ pgrep -u root sshd
Just look up pid for firefox process:
$ pgrep firefox

How to use ‘ps aux | grep command’

ps command shows information about a selection of the active processes:
$ ps aux
$ ps aux | grep -i ‘search-term’
$ ps aux | grep ‘firefox’
$ ps aux | grep ‘sshd’
OR use the following syntax instead of using egrep command in pipes:
$ ps -fC firefox
$ ps -fC chrome
The -C option asks ps command to select PIDs by command name.

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Using pidof command to grab PIDs for any named program on Linux

The pidof command finds the process id’s (pids) of the named programs such as sshd, firefox and more. For example:
$ pidof sshd
$ pidof firefox
Sample outputs:

A note about top/htop command

To display Linux processes use top command or htop command:
$ top
OR
$ htop

See also

Getting more help

Read the man pages for the following command using man command:
$ man pgrep
$ man pidof
$ man ps

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How do I count how many processes are running in Linux?

Viewing running processes in Linux

The ps command used to list the currently running processes and their PIDs in Linux and Unix-like systems. At a bare minimum, two processes displayed on the screen. For example, bash and ps might default on Linux when you just type ps command ps
Sample outputs:

Counts for each file in Linux

The wc is an acronym for word count. By default, wc command counts the number of lines, words, and characters in the text. For examples, show the newline counts
echo «line 1» | wc -l
To print the byte counts
echo «Hello» | wc -c
One can print the word counts as follows:
echo «Hello world» | wc -w

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Find how many processes are running in Linux

One can use the ps command along with with the wc command to count the number of processes running on your Linux based system by any user. It is best to run the following commands as root user using the sudo command.

Command to count the number of processes running in Linux

The Linux syntax is as follows:
# ps -e | wc -l
To see and count every process on the system using BSD syntax:
# ps axu | wc -l
Want to see and count every process running as vivek (real and effective ID) in user format, run:
$ ps -U vivek -u vivek u | wc -l
Another example for www-data user:
$ ps -U www-data -u www-data u | wc -l
In short to see and count only processes by a certain user naned root, you can use the following command:
sudo ps -U root | wc -l
sudo ps -U root -u root u | wc -l
Next we are going count process IDs of nginx using the following syntax:
ps -C nginx | wc -l
ps -C nginx -o pid= | wc -l

Pass the —no-headers or —no-heading to print no header line at all to get processes count correctly on Linux:
# ps -e —no-headers | wc -l
52
# ps -e | wc -l
53
When count real number of nginx it is a good idea to remove grep command while grepping using ps command:
ps -e —no-headers | grep [n]ginx
ps -e —no-headers | grep [n]ginx | wc -l

Understanding the wc command options

wc option	description
-c	Print the byte counts
-m	Print the character counts
-l	Print the newline counts
-w	print the word counts
—help	Display the wc command help and exit

Understanding the ps command options

ps option	description
-e	Select all processes (GNU/Linux syntax)
aux	Select all processes using BSD syntax
-U user	Select by real user ID (RUID) or name
-u user	Select by effective user ID (EUID) or name
-C cmdlist	Select by command name. This selects the processes whose executable name is given in cmdlist
—no-headers	Print no header line at all. —no-heading is an alias for this option

Conclusion

You learned how to list the number of processes running on the Linux or Unix like system using various command-line options. See the gnu ps help page here.

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How to check running process in Linux using command line

I am a new system administrator for the Linux operating system. How do I check running process in Linux using the command line option?

Tutorial details
Difficulty level	Easy
Root privileges	Yes
Requirements	Linux terminal
Est. reading time	4 mintues

One can use the Linux command line or terminal app to display a running process, change their priorities level, delete process and more. This page shows how to use various commands to list, kill and manage process on Linux.

Check running process in Linux

The procedure to monitor the running process in Linux using the command line is as follows:

1. Open the terminal window on Linux
2. For remote Linux server use the ssh command for log in purpose
3. Type the ps aux command to see all running process in Linux
4. Alternatively, you can issue the top command or htop command to view running process in Linux

Let us see some example and usage in details.

Please note that vivek@nixcraft:

$ is my shell prompt. You need to type commands after the $ prompt.

How to manage processes from the Linux terminal

The ps command is a traditional Linux command to lists running processes. The following command shows all processes running on your Linux based server or system:
vivek@nixcraft:

$ ps -aux
vivek@nixcraft:

1. root – User name
2. 1 – PID (Linux process ID)
3. 19:10 – Process start time
4. /sbin/init splash – Actual process or command

There may be too many processes. Hence, it uses the following less command/more command as pipe to display process one screen at a time:
vivek@nixcraft:

$ ps -aux | more
vivek@nixcraft:

$ sudo ps -aux | less
Press q to exit from above Linux pagers. You can search for a particular Linux process using grep command/egrep command:
vivek@nixcraft:

$ ps aux | grep firefox
vivek@nixcraft:

$ sudo ps aux | grep vim
vivek@nixcraft:

$ sudo ps -aux | egrep ‘sshd|openvpn|nginx’

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Linux pgrep command

Many variants of Linux comes with the pgrep command to search/find process. The syntax is:
vivek@nixcraft:

$ sudo pgrep sshd
vivek@nixcraft:

$ pgrep vim
vivek@nixcraft:

$ pgrep firefox
vivek@nixcraft:

Linux top command

The top command is another highly recommended method to see your Linux servers resource usage. One can see a list of top process that using the most memory or CPU or disk.
vivek@nixcraft:

$ sudo top
vivek@nixcraft:

Linux htop command to check running process in Linux

The htop command is an interactive process viewer and recommended method for Linux users. One can see a list of top process that using the most memory or CPU or disk and more:
vivek@nixcraft:

$ sudo htop
vivek@nixcraft:

Linux kill command

Want to kill a process? Try kill command. The syntax is:
vivek@nixcraft:

$ kill pid
vivek@nixcraft:

$ kill -signal pid
Find PID using ps, pgrep or top commands. Say you want to kill a PID # 16750, run:
vivek@nixcraft:

$ kill 16750
For some reason if the process can not be killed, try forceful killing:
vivek@nixcraft:

$ kill -9 16750
OR
vivek@nixcraft:

$ kill -KILL 16750

Linux pkill command

If you wish to kill a process by name, try pkill command. The syntax is:
vivek@nixcraft:

$ pkill processName
vivek@nixcraft:

$ pkill vim
vivek@nixcraft:

$ pkill firefox
vivek@nixcraft:

$ pkill -9 emacs
vivek@nixcraft:

$ sudo pkill -KILL php7-fpm

Linux killall command

The killall command kills processes by name, as opposed to the selection by PID as done by kill command:
vivek@nixcraft:

$ killall vim
vivek@nixcraft:

$ killall -9 emacs

Linux nice and renice command

The primary purpose of the nice command is to run a process/command at a lower or higher priority. Use the renice command to alter the nice value of one or more running Linux processes. The nice value can range from -20 to 19, with 19 being the lowest priority. Say, you want to compile software on a busy Linux server. You can set a very low priority, enter:
vivek@nixcraft:

$ nice -n 13 cc -c *.c &
Set a very high priority for a kernel update. Before rebooting Linux server, run:

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Linux list processes by user names (EUID and RUID)

Linux list processes by user names

The procedure to view process created by the specific user in Linux is as follows:

1. Open the terminal window or app
2. To see only the processes owned by a specific user on Linux run: ps -u
3. Search for a Linux process by name run: pgrep -u
4. Another option to list processes by name is to run either top -U or htop -u commands

Let us see examples in details to show all processes for a specific user on Linux.

How to see process created by a specific user in Linux

See all process crated by user named tom:
ps -u tom
OR
ps -U tom
EUID is the Effective User ID. The effective user ID describes the user whose file access permissions are used by the process. RUID is the Real User ID. The real user ID identifies the user who created the process. So:

• -u tom : Show all processes by RUID
• -U tom : Display all processes by EUID

You can get a list of every process running as vivek (real [RUID] & effective ID [EUID]) in user format:
ps -U vivek -u vivek
ps -U vivek -u vivek u
## see all process run by, qemu and postfix users ##
ps -U qemu -u qemu
ps -U postfix -u postfix
ps -U postfix -u postfix u

How to show all processes for a specific user using top/htop

The syntax is pretty simple to see all processes created by a user named vivek:
top -U vivek

Linux list processes by user name using top command

Linux show all processes created and used by a user named ‘vivek’ using htop

How to display user ID associated with a process

Another option is to use the combination of ps command and grep command/egrep command:
sudo ps -ef | grep
sudo ps -efl | grep
sudo ps -efl | grep vivek
sudo ps -ef | grep nginx
sudo ps -efl | grep ‘www-data’

The www-data user ID associated with a Linux process named lighttpd, nginx, and php-fpm.

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• -l : Long format
• -a : Show command line args
• -p : Display Linux PIDs
• -s : See parents of the selected process

The pgrep command

The pgrep command can look up processes based on usernames. The syntax is:
### Only match processes whose Linux effective user ID (euid) is listed ###
pgrep -u euid
### Only match processes whose effective user ID (uid) is listed ##
pgrep -U uid
pgrep -l -u vivek
pgrep -l -U www-data

Conclusion

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