CSL: General Linux/UNIX FAQ

This page attempts to answer some common Linux/UNIX questions that users might have. Please contact the Lab Staff if you have any comments, corrections, or suggestions.
Changing your password

To change your password, run the folowing command at the UNIX/Linux command-line prompt:


You will be prompted for your current password, and then for your new password (you'll have to type the new one twice). If your new password isn't sufficiently obscure, it will be rejected.

Changing your login shell

To change your login shell run the UNIX/Linux command:


You will be prompted for your password, and for the full path to the shell of your choice.

Checking group membership

You can check your group membership by using the UNIX/Linux groups command. Note that when you are added to a new group, you may need to login again for the new group membership to take effect.

You can check the membership of a particular group by using the getent command; for example to find the users belonging to the group cps131, you would use the following command:

	% getent group cps131 

where users fred and jones are the only members of this group. Note that this will not include group members who have the group ID as their primary group number in their passwrod entry

Group access to files

Department members make frequent use of UNIX groups to share files among group members. It is possible to set up shared directories such that all files created within the directory inherit the default group, (see the discussion about the group ID bit in the chmod man page), but it is up to the individual users to make sure the files have the proper permissions. This can either be handled manually, using the chmod command, as shown below:

% chmod g+w newfile

Alternatively, the user can affect all file creation permissions by changing their umask to 002 (the default is typically 022. Note if this method is chosen, this will affect all files created by the user!

Remote logins/Can't login to my desktop machine

If you are having trouble connecting to a department machine via ssh, please try connecting to login.cs.duke.edu first. Access to individual desktops is not guaranteed; these machines might be down for repairs or even be replaced entirely!

If you are experiencing problems logging into a known-available machine, particularly with the newer, Linux-based machines, you may have a problem with you account configuration files, or dot-files. Please see the Linux FAQ for more information.

Can't see project directories