pidof Command in Linux: Find Process IDs by Name

pidof is a command-line utility that allows you to find the process ID of a running program.

In this article, we will explain how to use the Linux pidof command.

How to Use the pidof Command #

There are different implementations of pidof for Red Hat and Debian based distributions. On Red Hat distributions, the pidof command is a part of the procps-ng package, while on Debian, it is part of sysvinit-utils. We will go over the options that are common to both implementations.

The syntax for the pidof command is as follows:

pidof [OPTIONS] PROGRAM_NAME

The command accepts zero or more names as arguments, but typically, you would pass only one name to pidof.

When invoked without any option, pidof will print the PIDs of all running programs that match with the given name. For example, to find the PID of the SSH server, you would run:

pidof sshd

If there are running processes with names matching sshd, their PIDs will be displayed on the screen. If no matches are found, the output will be empty.

4382 4368 811

pidof returns 0 when at least one running program matches with the requested name. Otherwise, the exit code is 1. This can be useful when writing shell scripts.

To be sure that only the PIDs of the program you are searching for are displayed, use the full pathname to the program as an argument. For example, if you have two running programs with the same name located in two different directories pidof will show PIDs of both running programs.

By default, all PIDs of the matching running programs are displayed. Use the -s option to force pidof to display only one PID:

pidof -s program_name

The -o option allows you to exclude a process with a given PID from the command output:

pidof -o pid program_name

When pidof is invoked with the -o option, you can use a special PID named %PPID that represents the calling shell or shell script.

To return only the PIDs of processes running with the same root directory, use the -c option. This option is ignored for non-root users, since they cannot check the root directory of processes they do not own. Run it as root or with sudo :

sudo pidof -c program_name

Example Usage of the pidof Command #

The following example shows how to use the pidof command in combination with the kill command to terminate a program.

Suppose the Firefox browser has become unresponsive, and you need to kill the Firefox processes. First, find the PIDs, with pidof:

pidof firefox

The command will print all Firefox processes:

2551 2514 1963 1856 1771

Once you know the Firefox PIDs, send them the default SIGTERM signal to ask the processes to exit gracefully:

sudo kill 2551 2514 1963 1856 1771

You can also use command substitution $(...) to find and terminate the program in a single command:

sudo kill $(pidof firefox)

If a process ignores SIGTERM and refuses to exit, send the stronger SIGKILL signal with kill -9 to force it to stop:

sudo kill -9 $(pidof firefox)

If you would rather match and signal processes by name in one step, the pkill and pgrep commands cover that workflow.

Quick Reference #

Both implementations support these commonly used options:

• -s - Single shot. Return only one PID.
• -c - Return only PIDs that share the same root directory (root or sudo only).
• -o pid - Omit the given PID from the output. The special value %PPID matches the calling shell or script.
• -x - Also match shells running a script with the given name.
• -q - Quiet. Print nothing and only set the exit status.

The sysvinit implementation used by Debian and its derivatives also supports:

• -z - Also detect processes stuck in zombie (Z) state.
• -n - Skip stat() calls on binaries that live on network filesystems such as NFS.
• -d sep - Use sep as the output separator instead of a space.

The procps-ng implementation used by Fedora, RHEL, and related distributions also supports:

• -w - Include processes without a visible command line, such as kernel worker threads.
• -t - Return thread IDs instead of process IDs.
• -S sep - Use sep as the output separator.

Run man pidof to confirm which options your installed implementation provides.

Conclusion #

The pidof command gives you a quick way to look up the PID of a running program by name, which is useful when you need to signal, monitor, or script around a specific process. Pair it with kill to stop a misbehaving program, or use the -s option when you only need a single PID.

About the authors

Dejan Panovski

Dejan Panovski is the founder of Linuxize, an RHCSA-certified Linux system administrator and DevOps engineer based in Skopje, Macedonia. Author of 800+ Linux tutorials with 20+ years of experience turning complex Linux tasks into clear, reliable guides.

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