Bash shell startup files in Debian Squeeze

Whenever I need to research which files are actually read or executed to set up the Bash environment at startup my brain refuses to cooperate. One thing is to understand the Bash manual about Startup Files and the Bash man page. That's still somewhat OK, but when I start looking at the actual file contents¹⁾ my gray matter's neurons begin to act in weird ways²⁾.

So, I ran my own tests on a fresh new installation of Debian Squeeze. To keep things simple, at first I only looked at shells invoked by ssh logins, su, /bin/bash and such. However, POSIX mode and /bin/sh are mentioned in the overview table. Anyway, here is what the tests boil down to.

Mainly, 4 files are read: /etc/bash.bashrc, /etc/profile, ~/.bashrc, ~/.profile

• Typical commands: ssh user@host, su - user, /bin/bash --login
• Startup files executed:
  1. /etc/profile, which also sources
  2. /etc/bash.bashrc and then all files matching
  3. /etc/profile.d/*.sh
  4. ~/.profile, which also sources
  5. ~/.bashrc

• Typical commands: su user, /bin/bash [-i], "subshells" as sometimes run by programs when they offer shells
• Startup files executed:
  1. /etc/bash.bashrc
  2. ~/.bashrc

• Typical commands: ssh [-t] user@host command, /bin/bash -c command, shebang style script shells (#!/bin/bash), and shells as run by programs when they offer shells, e.g. ^Z in nano
• Startup files executed:
  • None³⁾

Non-interactive shells either source $BASH_ENV, or in POSIX mode $ENV.

~/.profile is special because Bash actually looks for ~/.bash_profile, ~/.bash_login and ~/.profile, in this order, and Bash runs only the 1st of these 3 it finds (if it is readable). However, on a fresh Debian Squeeze ~/.bash_profile and ~/.bash_login do not exist; only ~/.bashrc, ~/.profile, and ~/.bash_logout.