Changing your shell
By default, ECE linux machines use bash(1) for their default shell; if you prefer to use another shell, you may change it with chsh(1), for example:
chsh -s /usr/bin/tcsh
You should bear in mind that if you are changing your shell on a machine that is part of a cluster or lab of machines, such as the color machines, the Wean Hall 3716 cluster, or the ECE cluster, you should ensure that you execute the chsh command on the lead machine of that cluster; otherwise, your change will only apply to that particular machine and will revert overnight to its previous state.
Shell Control Files
When you login to a unix-like system, your shell environment is described by various environment variables. You can see the entire list by executing
env. There are various methods to control your environment, including automatic execution of scripts to set these variables; these are called your shell control files.
How the shell was invoked affects which files will be executed for you upon startup.
It is a login shell if you have done one of the following:
ssh user@hostname logged in physically at the machine bash --login sudo su -
Bash will attempt to execute the following for you:
It is an interactive shell if you have done one of the following:
bash sudo su ssh user@hostname 'some command' start the shell from within a desktop environment such as KDE or GNOME
For interactive, non-login shell invocation, bash will attempt to execute only:
~/.bashrc should never echo output to the screen for the following reasons:
- scp/sftp will fail
- ssh user@hostname ‘some command’ will echo that output instead of the expected STDOUT from the ‘some command’.
It is a non-interactive shell if you have done one of the following:
sh somefile bash somefile bash -c somefile su user -c somefile
Bash will not automatically attempt to execute control files for non-interactive shells, you will need to manually source any files that you need to set environment variables or other customisations.