What's the difference between .bashrc, .bash_profile, and .environment?


I've used a number of different *nix-based systems of the years, and it seems like every flavor of Bash I use has a different algorithm for deciding which startup scripts to run. For the purposes of tasks like setting up environment variables and aliases and printing startup messages (e.g. MOTDs), which startup script is the appropriate place to do these?

What's the difference between putting things in .bashrc, .bash_profile, and .environment? I've also seen other files such as .login, .bash_login, and .profile; are these ever relevant? What are the differences in which ones get run when logging in physically, logging in remotely via ssh, and opening a new terminal window? Are there any significant differences across platforms (including Mac OS X (and its Terminal.app) and Cygwin Bash)?

1/6/2009 3:58:34 AM

Accepted Answer

The main difference with shell config files is that some are only read by "login" shells (eg. when you login from another host, or login at the text console of a local unix machine). these are the ones called, say, .login or .profile or .zlogin (depending on which shell you're using).

Then you have config files that are read by "interactive" shells (as in, ones connected to a terminal (or pseudo-terminal in the case of, say, a terminal emulator running under a windowing system). these are the ones with names like .bashrc, .tcshrc, .zshrc, etc.

bash complicates this in that .bashrc is only read by a shell that's both interactive and non-login, so you'll find most people end up telling their .bash_profile to also read .bashrc with something like

[[ -r ~/.bashrc ]] && . ~/.bashrc

Other shells behave differently - eg with zsh, .zshrc is always read for an interactive shell, whether it's a login one or not.

The manual page for bash explains the circumstances under which each file is read. Yes, behaviour is generally consistent between machines.

.profile is simply the login script filename originally used by /bin/sh. bash, being generally backwards-compatible with /bin/sh, will read .profile if one exists.

10/4/2012 5:16:54 AM

That's simple. It's explained in man bash:

       The bash executable
       The systemwide initialization file, executed for login shells
       The personal initialization file, executed for login shells
       The individual per-interactive-shell startup file
       The individual login shell cleanup file, executed when a login shell exits
       Individual readline initialization file

Login shells are the ones that are read one you login (so, they are not executed when merely starting up xterm, for example). There are other ways to login. For example using an X display manager. Those have other ways to read and export environment variables at login time.

Also read the INVOCATION chapter in the manual. It says "The following paragraphs describe how bash executes its startup files.", i think that's a spot-on :) It explains what an "interactive" shell is too.

Bash does not know about .environment. I suspect that's a file of your distribution, to set environment variables independent of the shell that you drive.

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