Package Management

sudo apt update
sudo apt install package
sudo apt remove package

sudo apt update && sudo apt upgrade -y
sudo apt install nginx postgresql-16
sudo apt search image-editor
apt list --installed | grep python

Note Always run apt update before installing to refresh package lists. apt is for Debian-based distributions (Debian, Ubuntu, Linux Mint, Pop!_OS). -y auto-confirms prompts. Use apt autoremove to clean up unused dependencies.

brew install formula
brew install --cask app
brew update && brew upgrade

brew install jq ripgrep tree
brew install --cask visual-studio-code
brew list
brew cleanup

Note Homebrew is the dominant package manager on macOS and also runs on Linux. Formulae are CLI tools; casks are GUI applications. Run brew update to refresh, brew upgrade to update all installed packages. brew cleanup removes old versions to free space.

sudo dnf install package
sudo yum install package

sudo dnf update
sudo dnf install httpd mariadb-server
sudo dnf search editor
sudo dnf remove old-package

Note dnf is the modern replacement for yum (Fedora 22+, RHEL 8+, CentOS Stream). yum still works on older CentOS/RHEL 7. Both resolve dependencies automatically. Use dnf list installed to see what is installed.

sudo snap install package
snap list

sudo snap install code --classic
sudo snap install node --channel=20/stable
snap list
sudo snap refresh

Note --classic is required for snaps that need broader system access (like editors and compilers). Snaps auto-update in the background. Available on Ubuntu by default and installable on most Linux distributions. snap refresh manually triggers updates.

which command
whereis command
command -v command

which python3
whereis gcc
command -v node || echo 'node not found'

/usr/bin/python3
gcc: /usr/bin/gcc /usr/lib/gcc /usr/share/man/man1/gcc.1.gz

Note which shows the full path of a command. whereis also shows man pages and source locations. In scripts, prefer command -v over which because it is POSIX-compliant and handles aliases/builtins correctly.