which

Additional Notes

which searches the directories in PATH and prints the executable file that would be found for a command name. It is useful for quick checks like finding whether python, node, or ssh is installed and where it lives.

which usually only answers executable path lookup. Shell aliases, functions, keywords, and builtins may need type, command -v, or declare -f for a complete shell-aware answer.

Syntax

which [options] command...

Parameters

• command: Command name to search for in PATH.
• options: Output behavior flags.

Common Options

• -a: Show all matching executables in PATH, not just the first one.
• --help: Show help when supported.
• --version: Show version information when supported.

Examples

which python

Show the first python executable found in PATH.

which -a node

Show every node executable found in PATH order.

which ssh

Find the SSH client executable.

command -v cd

Use shell-aware lookup for a builtin like cd.

Practical Notes

• PATH order matters. The first matching executable wins.
• Use type COMMAND when aliases, shell functions, builtins, or keywords matter.
• In portable scripts, command -v COMMAND is often preferable to which COMMAND.