Comparing whereis vs. which Command in Linux

In the vast ecosystem of Linux, the tools and commands at your disposal can often seem overwhelming. Among these, the whereis and which commands are pivotal when it comes to locating command binaries. While they might appear to serve similar purposes, their functionalities and outputs differ significantly. This guide aims to provide an in-depth comparison between the whereis vs. which commands in Linux, shedding light on their nuances and practical applications.

Introduction to the which Command in Linux

The which command is a utility that identifies the location of executables. It searches through the directories listed in the PATH environment variable and returns the path of the command that would be executed if invoked.

Syntax and Options of which

The basic structure of the which command is:

which [OPTION]... COMMAND...

Some commonly used options include:

  • -a: Print all matching pathnames of each argument.

For instance:

which -a python

This might return multiple paths if you have more than one version of Python installed.

Practical Application of which

To determine the location of the grep command, a tool used for pattern searching:

which grep

This might return:


The which command has shown that the grep command’s binary is located in the /bin directory. This is a standard directory for essential command binaries in Linux.

Introduction to the whereis Command in Linux

The whereis command, while also used for locating binaries, offers a broader search scope. It can locate not only the binary but also the source and manual page files for a command. It searches in a predefined set of directories, ensuring a balance between speed and comprehensiveness.

Syntax and Options of whereis

The basic structure of the whereis command is:

whereis [OPTION]... COMMAND...

Some key options include:

  • -b: Search only for binaries.
  • -m: Search only for manual sections.
  • -s: Search only for sources.

For example:

whereis -b ls

This will return only the binary location of the ls command.

Practical Application of whereis

To find out more about the ls command:

whereis ls

This might yield:

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

The whereis command has provided multiple paths. The first is the location of the binary, and the second is the location of its manual page. This comprehensive view is what sets whereis apart from which.

In-depth Comparisons of which vs whereis Command

Evaluating Speed and Detail

  • which Command:
    • Speed: The which command is optimized for speed. It’s a streamlined tool that exclusively searches the directories specified in the PATH environment variable. This focus makes it particularly swift, especially when you’re in need of immediate information regarding a command’s binary location.
  • whereis Command:
    • Detail: The whereis command, in contrast, offers a more exhaustive search. While this might make it marginally slower than which, it compensates by providing a richer set of details. Not only does it pinpoint the binary location, but it also identifies the locations of associated source files and manual pages.

Determining Use Cases

  • For Instant Binary Location:
    • When you’re scripting or in scenarios where you require a rapid check to ascertain a command’s binary location, the which command is your best bet. Its design caters to such quick look-ups, making it a preferred choice for many Linux users.
  • For a Holistic Overview:
    • If your requirements extend beyond just finding the binary location — say you’re interested in the source files, manual pages, or perhaps you wish to view all the locations associated with a particular command — the whereis command emerges as the superior choice. Its comprehensive output ensures you get a full picture of the command’s presence on your system.


The Linux operating system offers a plethora of commands and tools, each tailored for specific tasks. In the context of locating command binaries, both whereis and which play crucial roles. By understanding the differences and similarities between the whereis vs which commands in Linux, users can make more informed decisions, optimizing their workflows and ensuring they always have the right tool for their needs.

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