apropos

Updated

September 4, 2026

Overview

apropos searches man page names and short descriptions for keywords. Use it when you remember what you want to do but not the command name. It is equivalent to man -k.

It queries the whatis database built by mandb. If that DB is missing or stale, results will be empty or outdated — rebuild it rather than assuming the command does not exist.

Syntax

apropos [options] keyword...
man -k [options] keyword...

Common Options

Option	Description
`-a`	Require every keyword to match (AND)
`-r`	Treat keywords as regular expressions
`-w`	Shell-style wildcards
`-s list`	Limit to sections (e.g. `1,8`)
`-e`	Exact match on page name/description token
`-l`	Do not truncate long descriptions
`-C file`	Alternate man config file

Exact flags can vary slightly by man-db version; check man apropos on your host.

Examples with Explanations

Basic keyword search

apropos password
apropos socket
apropos 'disk usage'
man -k resize

Quotes help when the phrase contains spaces or shell metacharacters.

AND multiple terms

apropos -a network interface
apropos -a list directory

Without -a, multiple words are often OR’d (implementation-dependent noise). Prefer -a to narrow results.

Limit by section

apropos -s 8 mount          # admin tools about mount
apropos -s 1,8 kill         # user + admin kill-related pages
apropos -s 5 passwd         # file format, not the passwd(1) command

Regex and wildcards

apropos -r 'zip$'           # names/descriptions ending in zip
apropos -r '^ip\b'
apropos -w 'sched*'

Reduce noise to section-1 commands

apropos copy | grep -E '^\S+\s+\(1\)' | head -20
apropos -s 1 copy | head

Rebuild empty database

sudo mandb
# older / alternate systems:
# sudo makewhatis
apropos printf
whatis ls

Containers and minimal images often need man-db installed and mandb run once.

Pipeline into selection

cmd=$(apropos -s 1 disk | fzf | awk '{print $1}')
man "$cmd"

Handy on interactive workstations with fzf.

Compare with full-text search

apropos AddressFamily       # only names + short desc
man -K AddressFamily        # body text; much slower

Use -K when you know a config keyword but not which man page owns it.

Notes / Pitfalls

“nothing appropriate” usually means stale/missing mandb, not that Linux lacks the tool.
Descriptions are short; false positives are common (time matches many pages). Narrow with -s and -a.
Localized whatis DBs may hide English-only phrasing; try LANG=C apropos ….
apropos does not search shell builtins; use help / compgen -b for those.
Package docs not installed → no man page → not in the index.

2026-relevant notes

Prefer modern names in queries: apropos systemd, apropos nft, apropos iproute rather than only legacy ifconfig/iptables wording if you want current tooling.
On immutable / ostree systems, man pages may live in different layers; ensure the layer with docs is available before blaming apropos.
AI chat is fine for discovery, but apropos + man match your installed version’s flags.

Additional Resources

man apropos, man man, man mandb