Bash - Manual

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Notes and clipped sections from the Bash Manual (docs) to remember.

6.2 Bash Startup Files

This section describes how Bash executes its startup files. If any of the files exist but cannot be read, Bash reports an error. Tildes are expanded in filenames as described above under Tilde Expansion (see Tilde Expansion).

Interactive shells are described in Interactive Shells.

Invoked as an interactive login shell, or with —login

When Bash is invoked as an interactive login shell, or as a non-interactive shell with the —login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The —noprofile option inhibits this behavior.

When an interactive login shell exits, or a non-interactive login shell executes the exit builtin command, Bash reads and executes commands from the file ~/.bash_logout, if it exists.

Invoked as an interactive non-login shell

When Bash runs as an interactive shell that is not a login shell, it reads and executes commands from ~/.bashrc, if that file exists. The —norc option inhibits this behavior. The —rcfile file option causes Bash to use file instead of ~/.bashrc.

So, typically, your ~/.bash_profile contains the line

if [ -f ~/.bashrc ]; then . ~/.bashrc; fi

after (or before) any login-specific initializations.

Invoked non-interactively

When Bash is started non-interactively, to run a shell script, for example, it looks for the variable BASH_ENV in the environment, expands its value if it appears there, and uses the expanded value as the name of a file to read and execute. Bash behaves as if the following command were executed:

if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi

but does not the value of the PATH variable to search for the filename.

As noted above, if a non-interactive shell is invoked with the —login option, Bash attempts to read and execute commands from the login shell startup files.