Dotfiles

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Dotfiles are files in your home directory, usually at the root (ie /u/<username>) which start with a period and are therefore hidden from the output of a normal 'ls'. These tend to be used for configuration of various software programs, such as the shell you run, window managers, and many more. Some dotfiles are human-readable and can be easily edited, while others are better edited through the program that uses them via some built-in configuration interface.


Example Dotfiles

When a new account is created, all the files (except the '.svn' directory) that exist in /u/skel/Userfiles/ are copied to the new user's directory. These serve as the "default" files, though the system environments have been setup in such a way that even deleting all the files should give a user a "sane" default for everything that still works.


bash

The Bourne-Again SHell uses a few different files when it starts up. According to the manpage:

  • A login shell is one whose first character of argument zero is a -, or one started with the --login option.
  • An interactive shell is one started without non-option arguments and without the -c option whose standard input and error are both connected to terminals (as determined by isatty(3)), or one started with the -i option. PS1 is set and $- includes i if bash is interactive, allowing a shell script or a startup file to test this state.
  • The following paragraphs describe how bash executes its startup files. If any of the files exist but cannot be read, bash reports an error. Tildes are expanded in file names as described below under Tilde Expansion in the EXPANSION section.
  • 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 may be used when the shell is started to inhibit this behavior.
  • When a login shell exits, bash reads and executes commands from the file ~/.bash_logout, if it exists.
  • When an interactive shell that is not a login shell is started, bash reads and executes commands from ~/.bashrc, if that file exists. This may be inhibited by using the --norc option. The --rcfile file option will force bash to read and execute commands from file instead of ~/.bashrc.

If you look at the example files, you'll see that the majority of the commands to setup an environment are set in .bashrc and .bash_profile calls .bashrc if it exists. This way, you can keep a consistent environment between login and non-login shells, yet still have the distinction between the two in cases where it matters (such as things which might output text, that you don't care to see during a remote execution of a program that results in a non-login shell).