Linux apropos Command with Practical Examples

Introduction

In this lab, you will learn how to effectively use the Linux apropos command to search for relevant system commands and information. The apropos command allows you to search the system's manual pages (man pages) for commands that match a specific task or keyword, making it a valuable tool for exploring the available system utilities. You will start by understanding the purpose of the apropos command, then move on to performing basic searches and customizing your searches using regular expressions. This lab provides practical examples to help you become more proficient in utilizing the apropos command to find the right tools for your Linux system administration tasks.

Linux Commands Cheat Sheet

Skills Graph

Understand the Purpose of the apropos Command

In this step, we will explore the purpose of the apropos command in Linux. The apropos command is a powerful tool that allows you to search the system's manual pages (man pages) for relevant commands and information.

The apropos command is particularly useful when you need to find a command that performs a specific task, but you don't know the exact name of the command. It searches the one-line summaries of the man pages and displays the results, giving you a starting point to learn more about the relevant commands.

Let's start by running the apropos command with a simple search term:

sudo apropos "file search"

Example output:

find(1)               - search for files in a directory hierarchy
grep(1)               - print lines that match patterns
locate(1)             - find files by name

As you can see, the apropos command has returned a list of commands related to searching for files, which can be very helpful when you're trying to find the right tool for a specific task.

Now, let's try a more specific search:

sudo apropos "list directory contents"

Example output:

dir(1)                - list directory contents
ls(1)                 - list directory contents
vdir(1)               - list directory contents

This search returns commands that are specifically related to listing the contents of a directory, which is a common task in Linux.

The apropos command is a valuable tool for exploring the available system commands and finding the right tool for the job. In the next step, we'll dive deeper into performing more advanced searches with the apropos command.

Perform Basic Searches with the apropos Command

In this step, we will learn how to perform basic searches using the apropos command.

Let's start by searching for commands related to "file compression":

sudo apropos "file compression"

Example output:

bzip2(1)              - a block-sorting file compressor, v1.0.8
gzip(1)               - GNU compression utility
lzma(1)               - Compress or decompress .lzma and .xz files
tar(1)                - an archiving utility
xz(1)                 - Compress or decompress .xz and .lzma files
zcat(1)               - file decompression

As you can see, the apropos command returns a list of commands related to file compression, including bzip2, gzip, tar, and xz.

Next, let's search for commands related to "network configuration":

sudo apropos "network configuration"

Example output:

ifconfig(8)           - configure a network interface
ip(8)                 - show / manipulate routing, devices, policy routing and tunnels
netstat(8)            - Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
nmcli(1)              - command-line tool for controlling NetworkManager

This search returns commands related to network configuration, such as ifconfig, ip, netstat, and nmcli.

The apropos command can be a valuable tool for quickly finding relevant system commands and utilities. In the next step, we'll explore how to customize our searches using regular expressions.

Customize apropos Searches with Regular Expressions

In this final step, we will learn how to customize our apropos searches using regular expressions.

Regular expressions (regex) are a powerful way to perform more advanced and precise searches. They allow you to use special characters and patterns to match specific text within the man page summaries.

Let's start by searching for commands that contain the word "file" and end with the word "copy":

sudo apropos "file.*copy$"

Example output:

cp(1)                 - copy files and directories

The regular expression file.*copy$ matches commands that have the word "file" followed by any number of characters, and then end with the word "copy".

Next, let's search for commands that start with the word "list" and contain the word "directory":

sudo apropos "^list.*directory"

Example output:

dir(1)                - list directory contents
ls(1)                 - list directory contents
vdir(1)               - list directory contents

The regular expression ^list.*directory matches commands that start with the word "list" and contain the word "directory" anywhere in the summary.

Regular expressions can be quite powerful, but they can also be complex. It's a good idea to practice and experiment with different patterns to get a feel for how they work.

Remember, you can always refer to the man 7 regex page for more information on regular expression syntax and usage.

Summary

In this lab, we learned about the purpose and usage of the apropos command in Linux. The apropos command allows us to search the system's manual pages (man pages) for relevant commands and information, particularly when we don't know the exact name of a command. We performed basic searches using apropos to find commands related to file search and directory listing, and learned how to customize our searches with regular expressions.

The apropos command is a valuable tool for exploring the available system commands and finding the right tool for the job. It provides a starting point to learn more about the relevant commands and their functionalities.

Linux Commands Cheat Sheet