apt-file

Update the metadata database

$ sudo apt update

$ apt-file [search|find] [path/to/file]

$ apt-file [show|list] [package]

$ apt-file [search|find] [[-x|--regexp]] [regex]

apt-file [options] {update|search|list|show|contents|autoclean|clean} [pattern|package]

-c, --cache DIR
    Use DIR for cache storage

-D, --deb-path DIR
    Search deb files in DIR for local packages

-x, --regex
    Treat pattern as regular expression

-F, --from-file FILE
    Read search patterns from FILE, one per line

-i, --ignore-case
    Ignore case in pattern matching

-l, --list-changes
    List only changed package contents

-w, --wildcard
    Enable wildcard (*) matching

-y, --yes
    Automatically answer 'yes' to prompts

-v, --verbose (-vv)
    Increase verbosity (twice for more)

-q, --quiet (-qq)
    Reduce output (twice for silent)

--explain
    Explain search criteria and results

-h, --help
    Display help and exit

-V, --version
    Show version information

apt-file is a powerful command-line tool for Debian-based Linux systems like Ubuntu, designed to locate files provided by any package in the APT repositories, even if not installed. It maintains a local database of package contents, enabling quick searches for libraries, headers, binaries, or config files during troubleshooting, compilation, or dependency resolution.

Unlike dpkg -S, which only queries installed packages, apt-file indexes all available packages from configured repositories. This makes it invaluable for scenarios like "which package provides /usr/include/foo.h?" or finding missing shared objects.

Workflow: Install via sudo apt install apt-file, initialize the database with sudo apt-file update (downloads package lists and indexes files, ~100-500MB). Search with apt-file search pattern, where pattern can be a filename, path fragment, or regex (with -x). Results show matching packages and file paths.

Key features include case-insensitive matching (-i), wildcards (-w), multi-pattern from file (-F), and verbose/quiet modes. List package contents with apt-file list pkg or bulk via apt-file contents pkg. Maintenance commands like autoclean remove stale indices, keeping the cache efficient.

It's widely used by developers and sysadmins for rapid package discovery, reducing reliance on web searches or manual repo browsing. Regular updates ensure accuracy as repositories evolve.

Requires root for update (downloads/indexes repos).
Database grows large (100-500MB+); use autoclean regularly.
Accuracy depends on fresh apt-file update after repo changes.
May miss very new/unindexed packages.

sudo apt update && sudo apt install apt-file
sudo apt-file update (first run takes time).

apt-file search libcrypto.so — find SSL library.
apt-file list vim — list vim package files.
apt-file -x search 'foo[.]h' — regex header search.

apt-file autoclean — remove outdated indices.
apt-file clean — delete entire cache.

Developed by Eric Dorland in 2003 for Debian. Integrated into apt-file package, maintained in Debian/Ubuntu repos. Evolved with regex/wildcard support; key tool for pre-APT 1.0 dependency hunting.

apt-cache(8), dpkg-query(1), apt(8), dpkg(1), find(1)