which

Locate a command and display its absolute path

Description

The which command is used to find and display the absolute path of a given command. It searches for executable files in the directories specified by the PATH environment variable. By using which, you can check if a certain system command exists and exactly which file will be executed when you type the command.

Syntax

which [options] [command]

Options

-a  Print all matching executables in PATH, not just the first one.
-n <length>  Specify the minimum filename length.
-p <length>  Same as -n, but includes the path.
-w  Specify the width of the output columns.
-V  Display version information.

Parameters

command: A list of command names to locate.

Examples

Find the path of a command:

[root@localhost ~]# which pwd
/bin/pwd

[root@localhost ~]# which adduser
/usr/sbin/adduser

Note: which searches based on the PATH variable. Different PATH settings will yield different results.

Try to find cd:

[root@localhost ~]# which cd
cd: shell built-in command

In some systems, which might not find cd because it's a shell builtin and not a standalone executable file in PATH.