Shell Aliases and Functions That Save Time

If you type the same long command more than a few times a day, the shell can do the typing for you. Aliases and functions are the two tools for this, and picking the right one avoids a lot of confusion. Here is what I have settled on after years of tweaking.

Alias or function?

An alias is plain text substitution at the start of a command line. It is perfect for shortening a command with fixed options. The limitation is that arguments are only appended at the end, so an alias cannot place them in the middle or run several steps with logic.

A function is a small shell script living in your session. It takes positional arguments ($1, $2, "$@"), can use conditionals, and can run multiple commands. My rule: start with an alias, and switch to a function the moment you need an argument anywhere but the end.

Aliases worth having

# git
alias gs='git status -sb'
alias gl='git log --oneline --graph --decorate -20'
alias gd='git diff'

# safer file operations
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'

# navigation and listing
alias ll='ls -lAh'
alias ..='cd ..'

On the rm -i line: it prompts before every deletion, which saves you once and annoys you often. Many people prefer a trash tool such as trash-put from the trash-cli package, which moves files to the desktop trash so they can be restored. Whichever you choose, make it a deliberate habit rather than relying on luck.

Functions for the rest

mkcd() {
  mkdir -p -- "$1" && cd -- "$1"
}

extract() {
  case "$1" in
    *.tar.gz|*.tgz) tar xzf "$1" ;;
    *.tar.bz2)      tar xjf "$1" ;;
    *.tar.xz)       tar xJf "$1" ;;
    *.zip)          unzip "$1" ;;
    *.gz)           gunzip "$1" ;;
    *) echo "extract: unknown format: $1" >&2; return 1 ;;
  esac
}

alias ports='ss -tulpn'

note() {
  local dir="$HOME/notes"
  mkdir -p "$dir"
  echo "$(date +%H:%M) $*" >> "$dir/$(date +%F).md"
}

mkcd creates a directory and enters it, which no alias can do cleanly. extract saves you from remembering tar flags. ports lists listening TCP and UDP sockets with their processes (run it with sudo to see processes you do not own). note appends a timestamped line to a file named after today’s date, so note fix flaky test in CI is a one-second capture. My notes CLI grew out of exactly this function.

Where to put them

Bash reads ~/.bashrc for interactive shells. Many distributions already source ~/.bash_aliases from it, which keeps your additions separate. If yours does not, add one line:

export EDITOR=vim
[ -f ~/.bash_aliases ] && . ~/.bash_aliases

Then reload with source ~/.bashrc. For zsh, the same code goes in ~/.zshrc (or a sourced file); the aliases and the functions above work unchanged.

Inspecting what you have

alias            # list all aliases
alias gs         # show one
type gs          # gs is aliased to `git status -sb'
type mkcd        # shows the function body
unalias gs       # remove for this session
command rm file  # bypass the alias once (or use \rm)

type is the most useful of these because it tells you whether a name is an alias, a function, a builtin, or a file on disk.

Keeping them tidy and portable

• Keep one file under version control, such as a dotfiles repository, and symlink it.
• Prefer descriptive function names over two-letter cryptic ones unless you type them constantly.
• Avoid shadowing common commands with different behavior; scripts you run interactively may surprise you.
• Guard anything non-portable, for example command -v trash-put >/dev/null && alias rm='trash-put'.
• Remove what you have not used in months.

If you are still building up your command-line basics, Linux terminal essentials is a good companion.

What to do next

Run history | awk '{print $2}' | sort | uniq -c | sort -rn | head to see your most-used commands, then turn the top three into aliases today. Add a function only when an alias stops being enough.