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Dotfiles

Shell overview

The repo supports bash and zsh with feature parity — the same aliases, functions and prompt in both. Use zsh on your laptop and bash on a server; nothing to relearn.

zsh is the default shell on macOS (since Catalina, 2019) and Kali Linux. Ubuntu, Debian, Fedora, Arch, Alpine and the usual Docker images default to bash (or plain sh). The installer installs zsh for you if you pick it — see Install.

Which file loads when

Section titled “Which file loads when”

A shell reads different startup files depending on how it was started:

  • Login shell — the first shell after you log in: SSH, a console login, macOS Terminal.
  • Interactive shell — one you type into: every new terminal tab.
  • Non-interactive — scripts, cron jobs, ssh host 'some command', editors running commands.
                      zsh                              bash
                      ───                              ────
every zsh       →  ~/.zshenv                     (no equivalent)
login           →  ~/.zprofile                   ~/.bash_profile  ← all real config
interactive     →  ~/.zshrc                      ~/.bashrc  ──→ loads ~/.bash_profile
                      │                                │
                      └──── both load ────┬────────────┘
                                          ▼
                    ~/.aliases   ~/.functions   (+ *.local versions)
zsh runs when bash equivalent what goes here
.zshenv every zsh — interactive, login, scripts, cron, GUI apps none PATH, environment variables everything needs
.zprofile login shells, before .zshrc .bash_profile once-per-login setup (ssh-agent, tmux auto-attach)
.zshrc interactive shells (every new tab) .bashrc aliases, functions, prompt, completion, key bindings
.zlogin login shells, after .zshrc .bash_login (rare) login setup that needs the shell fully configured
.zlogout leaving a login shell .bash_logout cleanup

This repo ships .zshenv, .zprofile and .zshrc. .zlogin and .zlogout aren’t used.

Why the split matters

Section titled “Why the split matters”

Most personal config can live in .zshrc. The split matters when:

  • Something must run only once per session. The classic example is ssh-agent: in .zshrc every new tab starts a new agent; in .zprofile every tab shares the same one.
  • Something must be visible outside the prompt. Cron jobs, GUI apps and scripts only read .zshenv. That’s why PATH lives there — a cron job calling a Homebrew tool would fail if Homebrew’s PATH was only set in .zshrc.

bash has no file that runs for every invocation (no .bash_env equivalent). Its split is login (.bash_profile) vs. interactive (.bashrc). This repo puts everything in .bash_profile and makes .bashrc load it — see bash.

Shared aliases and functions

Section titled “Shared aliases and functions”

.aliases and .functions are one file each, loaded by both shells. Shell-specific bits sit behind a check:

Terminal window
if [[ -n "$ZSH_VERSION" ]]; then
  alias dang='sudo $(fc -ln -1)'          # zsh way to get the last command
elif [[ -n "$BASH_VERSION" ]]; then
  alias dang='sudo $(history -p \!\!)'    # bash way
fi

$ZSH_VERSION and $BASH_VERSION are set by the shell itself and aren’t exported, so exactly one of them is set in any given shell.

File naming

Section titled “File naming”

Names without a bash_ or zsh_ prefix (.aliases, .functions) signal “works in both”. Keeping one shared file avoids two copies drifting apart. The shell doesn’t care about the name — it loads whatever path the startup file points to.

.zshrc also still loads the older names (.zsh_aliases, .zsh_functions and their .local versions) if they exist, so an old setup keeps working.

Detecting Linux vs. macOS

Section titled “Detecting Linux vs. macOS”

Many commands differ between GNU (Linux) and BSD (macOS) — ls colour flags, how to lock the screen, where the Trash lives. The configs detect the OS once and set IS_LINUX or IS_MACOS; aliases then pick the right command.

There are two ways to detect the OS:

$OSTYPE $(uname -s)
Works in bash, zsh every shell, including sh, dash, BusyBox ash
Cost free — set by the shell starts a small program, ~1–5 ms

This repo uses uname -s (portable) but only runs it once: .zshenv sets the variables, and .aliases skips its own check when they’re already set:

Terminal window
# "$IS_MACOS$IS_LINUX" joins both into one string — empty only if neither is set.
# Same as [[ -z "$IS_MACOS" && -z "$IS_LINUX" ]], just shorter.
if [[ -z "$IS_MACOS$IS_LINUX" ]]; then
  case "$(uname -s)" in
    Darwin) IS_MACOS=1 ;;
    Linux)  IS_LINUX=1 ;;
  esac
fi

In bash there’s no .zshenv, so .aliases does the check itself — once per shell start.

Pages in this section

Section titled “Pages in this section”