apt Common Commands

Repository Updates

Command	Description
`sudo apt update`	Update package index
`sudo apt upgrade`	Upgrade all installed packages
`sudo apt full-upgrade`	Upgrade packages and automatically handle dependency changes
`sudo apt dist-upgrade`	Same as full-upgrade

Install and Remove

Command	Description
`sudo apt install package-name`	Install a package
`sudo apt install package-name=version`	Install a specific version
`sudo apt install ./package.deb`	Install a local .deb file
`sudo apt reinstall package-name`	Reinstall a package
`sudo apt remove package-name`	Remove a package (keep configuration)
`sudo apt purge package-name`	Remove a package and delete configuration files
`sudo apt autoremove`	Remove dependencies that are no longer needed

Search and Query

Command	Description
`apt search keyword`	Search for packages
`apt show package-name`	Show package details
`apt list --installed`	List installed packages
`apt list --upgradable`	List upgradable packages
`apt depends package-name`	Show dependencies
`apt rdepends package-name`	Show reverse dependencies
`dpkg -L package-name`	List all files installed by a package
`dpkg -S /path/to/file`	Find which package owns a file

Cache Cleanup

Command	Description
`sudo apt clean`	Clear all downloaded cache
`sudo apt autoclean`	Clear only outdated cache
`sudo apt autoremove --purge`	Remove dependencies and purge configuration

Version Pinning

Command	Description
`sudo apt-mark hold package-name`	Hold a package version (prevent upgrades)
`sudo apt-mark unhold package-name`	Unhold a package
`apt-mark showhold`	Show held packages

Repair

Command	Description
`sudo apt --fix-broken install`	Fix dependencies
`sudo dpkg --configure -a`	Reconfigure interrupted packages

Repository Management

Command	Description
`sudo add-apt-repository ppa:xxx/yyy`	Add a PPA
`sudo add-apt-repository --remove ppa:xxx/yyy`	Remove a PPA
`cat /etc/apt/sources.list.d/ubuntu.sources`	View configured sources
`grep -rh "^deb " /etc/apt/sources.list.d/`	List all sources

Signing Third-Party Repositories (apt-key removed)

APT 3.1 has fully removed apt-key, and the global keyring is no longer trusted. When adding a third-party repository, store the key separately in /etc/apt/keyrings/ and point to it explicitly with Signed-By in the source entry.


# 1. Download the key and convert it to a binary keyring (de-armored)
sudo install -d -m 0755 /etc/apt/keyrings
curl -fsSL https://example.com/repo.gpg \
  | sudo gpg --dearmor -o /etc/apt/keyrings/example.gpg
sudo chmod 0644 /etc/apt/keyrings/example.gpg

Prefer the deb822 format (.sources files), binding the key with Signed-By:


# /etc/apt/sources.list.d/example.sources
Types: deb
URIs: https://example.com/apt
Suites: noble
Components: main
Signed-By: /etc/apt/keyrings/example.gpg

For the legacy one-line format (.list files), use the signed-by= option:


# /etc/apt/sources.list.d/example.list
deb [arch=amd64 signed-by=/etc/apt/keyrings/example.gpg] https://example.com/apt noble main

Tip

Giving each repository its own keyring that signs only its own repository prevents one third-party key from being used to forge official packages — far safer than the old global apt-key.

Simulation and Download

Command	Description
`apt install -s package-name`	Simulate installation (dry run)
`apt download package-name`	Download without installing

Useful Tips

Command	Description
`apt changelog package-name`	View package changelog
`apt policy package-name`	Show which repository provides the package
`grep ^Package /var/lib/apt/lists/repo-name*_Packages \| sort -u`	List all packages from a specific repository