which vs whereis vs locate: Find Where a Command Lives

2026-06-01 Reading time: About 15 min Difficulty: Introduction

What You Will Learn

By the end of this article you will be able to:

• Use which to find the executable pathA string that describes the location of a file or directory. of a command
• Use whereis to find the binary, man page, and source at once
• Use locate to search for any file by name, fast
• Know which tool to reach for in which situation

1. which — "Which executable does my shell actually run?"

Conclusion: which searches PATH in order and prints the one executable your shellAn interactive program that reads the commands you type and runs them. runs.

Basic usage

which python3

/usr/bin/python3

which searches the directories listed in your PATH environment variableA named value that the shell or a program can look up while running., in order, and prints the first match it finds.

which git

/usr/bin/git

When a command is not found

which nonexistent-command

No output (exit code 1). Some distributions print a message like:

which: no nonexistent-command in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)

Useful when multiple versions are installed

which python
which python3

/usr/bin/python
/usr/bin/python3

You can see at a glance which version each name maps to.

Check aliases and shell builtins too: type -a / command -v

Fedora and RHEL-family systems behave differently. The bash package installs wrapper scripts such as /usr/bin/cd for the builtins, so which cd prints that path, and in interactive shells /etc/profile.d/which2.sh makes which show aliases and shell functions as well. Whatever the system, type -a is the reliable way to see what actually runs. (Source: Fedora bash.spec, Fedora which2.sh, CentOS Stream 9 bash.spec / which2.sh, retrieved 2026-09-25)

type -a cd
type -a ls

cd is a shell builtin
ls is aliased to `ls --color=auto'
ls is /usr/bin/ls
ls is /bin/ls

type -a lists every match — aliases, shell builtins, and executables in your PATH. The first line is what actually runs. (Both /usr/bin/ls and /bin/ls appear on systems where /bin is a link to /usr/bin.)

Inside a shell script, use command -v to check whether a command is available. It is defined by POSIX.

command -v git
command -v cd

/usr/bin/git
cd

When nothing matches, it prints nothing and returns exit code 1, so you can use it in a condition: if command -v git >/dev/null 2>&1; then ... fi.

2. whereis — "Show me the binary, man page, and source together"

Conclusion: whereis finds the binary, man page, and source at once, ignoring your PATH.

Basic usage

whereis ls

ls: /usr/bin/ls /usr/share/man/man1/ls.1.gz

/usr/bin/ls is the executable. /usr/share/man/man1/ls.1.gz is the compressed man page.

whereis python3

python3: /usr/bin/python3 /usr/lib/python3 /usr/share/man/man1/python3.1.gz

What each field means

Filtering with options

whereis -b ls   # binary only
whereis -m ls   # man page only
whereis -s ls   # source only

ls: /usr/bin/ls
ls: /usr/share/man/man1/ls.1.gz
ls:

3. locate — "Search for any file by name, fast"

Conclusion: locate queries a prebuilt database to find any file by name, very fast.

Basic usage

locate ssh_config

/etc/ssh/ssh_config
/usr/share/doc/openssh-client/examples/ssh_config

Why is it so fast?

locate does not scan the filesystem in real time. It queries a pre-built database (index), which is why it returns results almost instantly.

Rebuild the database manually

sudo updatedb

Run this after creating new files, then locate will find them.

Case-insensitive search

locate -i README

/home/user/projects/readme.md
/usr/share/doc/curl/README
/usr/share/doc/git/README.md

Combine with grep to filter results

locate nginx | grep conf

/etc/nginx/nginx.conf
/etc/nginx/conf.d/default.conf

Count matches without listing all paths

locate -c python

248

4. Choosing the Right Command

Conclusion: Use which for paths, whereis for related files, locate to search names.

5. Common Questions and Pitfalls

Conclusion: When which is empty, use whereis or locate; run updatedb for fresh data.

Q. which returns nothing — is the command really installed?

# Check PATH
echo $PATH

# Broader search
whereis node

# Search common bin directories
locate node | grep "/bin/"

Q. locate returns stale results

If a file you just created does not appear:

sudo updatedb
locate the-file-you-want

Q. locate command not found

On current major distributions, locate comes from the plocate package. plocate is a compatible reimplementation of the older mlocate, so locate and updatedb work the same way.

# Ubuntu 22.04 and later / Debian 12 and later
sudo apt install plocate

# Fedora 36 and later / Rocky Linux 10, AlmaLinux 10, etc.
sudo dnf install plocate

On older distributions, use the mlocate package.

# Ubuntu 20.04 / Debian 11, etc.
sudo apt install mlocate

# Rocky Linux 9 / AlmaLinux 9, etc.
sudo dnf install mlocate

(Source: Ubuntu Packages Search: mlocate / plocate, Launchpad: mlocate in Ubuntu Focal, Debian package search: mlocate / plocate, Fedora Changes/Plocate as the default locate implementation, Rocky Linux 9 BaseOS / 10 BaseOS, AlmaLinux 9 BaseOS / 10 BaseOS, retrieved 2026-09-25)