How Apropos Linux Command Makes Discovery Simple

The apropos Linux command helps users locate any command through its man pages. Man pages explain command functions, outline relevant arguments, and offer examples of usage.

The man command accesses the Linux command manual using the man command_name format. Thus, if you don’t know the command name, it can be an issue. In contrast to man, apropos scans all man pages using known information as a search term.

How apropos Linux Works

Syntax and basic usage

To start, connect to the server using SSH. The basic structure of the apropos command is pretty straightforward:

apropos [option] keyword

The apropos The command works without options, but does not work without a search term (keyword).

Since the Linux apropos command searches for a keyword in names and descriptions of man pages, running the command without a keyword prints the following:

Practical Examples for Everyday Users

Searching for a command using a keyword is super useful when you can’t recall the exact command or when you’re looking for a fitting command to carry out a task.

apropos Linux comes in handy in these scenarios and has a ton of applications. Here are a few examples.

1. Find a Keyword

The main purpose of apropos is to locate a single keyword in man pages. For example, you can run apropos list to find mentions of the keyword list:

apropos list

This command displays all occurrences of list in names (highlighted in green) and descriptions (highlighted in yellow). It also shows matches that are part of larger strings, like listener or lists.

2. Search Two Keywords

If the keyword is too general, apropos Linux will return a lot of results. For the keyword list, apropos generates 300 lines.

To narrow down the results, add another variable. For example, to list all directories, use two keywords with apropos: list and directories.

Without any arguments, apropos searches man pages that contain either list or directory. To make sure the output includes both, use -a:

apropos -a list directory

You can achieve a similar result without -a by putting keywords in double quotes:

apropos "list directory"

Double quotes tell apropos to look for the exact match, keeping the same order as the keywords in quotes. Therefore, the output gives you four lines instead of six when using -a.

Enhance Your CyerPanel Experience Today!

Discover a world of enhanced features and show your support for our ongoing development with CyberPanel add-ons. Elevate your experience today!

Learn More

Find Either of Two Parameters

While the -a option works like a logical AND, using apropos with multiple search terms without arguments acts like a logical OR.

For instance, you can use delete, terminate, and remove as search terms to find man pages that include any of the keywords:

apropos delete terminate remove

The apropos command will print lines that contain one or more of the keywords.

Find Exact Match

The apropos command matches individual keywords or parts of other words. For example:

apropos set

The output will show instances of the set included in strings like offset and settings. To find exact matches for set, use the -e flag:

apropos -e set

Search Specific Sections

A manual page for each command is divided into nine sections. For example:

man man

By default, apropos looks for the keyword in all sections. To narrow down the search to a specific manual section, use -s followed by the section number(s).

For example, to search for list in sections 1 and 8, use the following command:

apropos -s 1,8 list

The command displayed man pages that included list in either section 1 or 8.

Use Regex Symbols

Utilize regex symbols to enhance the search speed and refine the results.

For example, to find all man pages that start with the word list, use:

apropos '^list'

The term list is placed in single quotes with the caret symbol, ensuring it appears at the start of the line. The output indicates that list is found at the beginning of either the name column or the description column.

Regex expressions provide even more flexibility. For instance, to find every man page that contains zipcloak, zipnote, or zipinfo, use:

apropos "zip(note|cloak|info)"

The pipe acts as a logical OR. The apropos command searches for zip followed by either cloak, note, or info.

Employ regex for a more targeted search. For example, to find implementation, devices, or users in sections 3 or 8 on any man page that begins with list:

apropos -a -s 3,8 "^list" "(implementation|devices|users)"

In the output, you’ll see that each line starts with a list, belongs to section 3 or 8, and contains one of the specified keywords.

Avoid Trimming

By default, the apropos command truncates the description in the output. The output ends with an ellipsis. When executing apropos with a list, the trimming is noticeable in certain areas:

split -b 100M --numeric-suffixes=1 --additional-suffix=.txt largefile.log part_

Trimming occurs regardless of the window size. To prevent trimming, use the -l option:

Limitations of the Apropos Command in Linux

• Large databases can take more time to yield results unless specific options are used.
• Results might include unrelated commands. Use options such as e for regular expressions and w for precise matches.
• The reliance on the man-db package may cause issues if it is not installed or kept up to date.

Important Notes:

• Frequently update the manual database to ensure accurate results.
• Use apropos in conjunction with other Linux commands to improve functionality.
• Make sure that custom applications with manual pages are indexed by mandb so that apropos can locate them.

Why Apropos Linux is Still a Must-know Command For Linux Users in 2025

The apropos command is a powerful tool for navigating Unix-like manual pages, enhancing workflows for beginners and advanced users. Mastering its options and applications can enhance Linux experience.

FAQ’s

1. What is the apropos command in Linux?

The apropos command in Linux is utilized to search through the manual page (man page) descriptions for commands that relate to a specific keyword. It assists users in quickly locating relevant commands without needing to know their exact names.

2. How do I use the apropos command?

To use apropos, simply type:

apropos keyword

For instance:

apropos network

This will display all commands associated with networking, along with their brief man page descriptions.

3. What is the difference between man -k and apropos Linux?

Both commands serve the same purpose. The apropos command is essentially the same as:

man -k keyword

They both search the man page database for commands and descriptions that match.

4. Why is apropos not showing results on my Linux system?

If apropos yields no results, it is typically due to the man database being outdated or absent. You can refresh it by using:

sudo mandb

After the update, apropos should function properly.

5. Can I search multiple keywords with apropos?

Yes, you can search for multiple keywords by combining them with quotes or using regex. For example:

apropos "network|socket"

This will look for commands related to both network and socket.

6. Is apropos Linux available on all Linux distributions?

Yes, apropos is included in the man-db package, which is found in nearly all Linux distributions. If it is not installed, you can add it using:

sudo apt install man-db # Debian/Ubuntu<br>sudo yum install man-db # CentOS/RHEL<br>sudo dnf install man-db # Fedora