How to Find Programs with which, whereis and locate

Published 2026-08-05 · Learn Linux

Three commands answer Where is this program? which shows the path that runs when you type a command, whereis also finds manuals and sources, and locate searches a database of every file on the system in a flash.

Find a command's path with which

which command prints the location that would run, based on your PATH. If it prints nothing, the command is not installed or not in PATH.

$ which python3

$ which -a php

Find binaries, manuals and sources with whereis

whereis searches standard locations for the binary, the man page and the source of a program at once.

$ whereis bash

Search everything fast with locate

locate looks up file names in a prebuilt database, so it is nearly instant across the whole system. Use a wildcard for partial names:

$ locate nginx.conf

Keep locate's database fresh

locate only knows files that were in the database when it was last updated. Refresh it with updatedb (root), usually run daily by cron.

$ sudo updatedb

Which one should you use?

Typing a command that is missing: which. Checking a program's docs: whereis. Finding any file anywhere: locate. For a fully current search, use find. See the which, whereis and locate reference pages.