Bash configuration filesEdit

Created , updated

This is my attempt to phrase the "INVOCATION" section of the Bash man page in the clearest possible terms.

Definitions

A "login" shell is:

  • a shell whose argument zero starts with -; or
  • a shell invoked with the --login or -l (equivalent) option

Examples of login shells:

  • the shell you get when you:
    • open a new terminal window
    • open a new tab in a terminal window
    • open a new pane in a tmux session

Note: This behavior may vary according to your terminal program; it is true for Mac OS X, but this article claims the behavior is the opposite in some Linux distros.

An "interactive" shell may be:

  • a login shell as described above; or
  • any other shell whose standard input and output are connected to a real terminal (ie. the kind of shell you get if you type bash or sh)
  • a shell started with -i

A "non-interactive" shell may be:

  • a shell started to run a shell script
  • a shell started to run a command (eg. sh -c ls)

Startup behavior

  • sh:
    • run as an interactive login shell (unless inhibited with the --no-profile option):
      1. runs /etc/profile
      2. runs ~/.profile, if it exists
    • run as an interactive non-login shell (eg. if you just type sh)
      1. runs nothing
    • run as a non-interactive shell with the --login or -l options:
      1. runs /etc/profile
      2. runs ~/.profile, if it exists
  • bash:
    • run as an interactive login shell (unless inhibited with the --no-profile option):
      1. runs /etc/profile
      2. runs first found, readable file among ~/.bash_profile, ~/.bash_login and ~/.profile
      3. runs ~/.bash_logout, if present, on logout
    • run as an interactive non-login shell (eg. if you just type bash):
      1. runs ~/.bashrc (unless inhibited with the --no-rc option)
    • run as a non-interactive shell with the --login or -k options:
      1. runs /etc/profile
      2. runs first found, readable file among ~/.bash_profile, ~/.bash_login and ~/.profile
      3. runs ~/.bash_logout, if present, on logout
    • run as a non-interactive shell (eg. bash -c ls):
      1. runs nothing

Consequences

  • For most intents and purposes, you can count on ~/.bash_profile (or similar) running for pretty much any shell you open.
  • It’s recommended that you put base config (things like PATH exports) in your ~/.bashrc and fancy stuff (prompt set-up etc) in your ~/.bash_profile; you can source you ~/.bashrc from your ~/.bash_profile to that you don’t have to duplicate the basic config

See also