Unix Account Configuration
Configuring Your Dot Files
"Dot files" are files in which the first character of the
filename is a "." (dot or period). In UNIX, such files are
hidden in the sense that the "ls" command will not display
them by default. These files usually contain configuration
information needed by different programs.
To list the dotfiles in a directory, type the following command:
ls -a
To copy dotfiles, type the following command:
cp .* <target_location>
Please note: Your UNIX environment is loaded when
you log in and every time you open a new xterm. After making changes
to your dot files you will need to either logout and log back in, or
open a new xterm in order for the changes to take effect. When you
open a new xterm, your environment will be loaded using the modified
dot file.
Be sure to test any changes you have made to your dotfiles before
logging out. It is possible to disable your account with a simple
typo in your edits. To test your new configuration, log into a
different computer with your new settings. If you are unable to
successfully open a new X session, you probably have a typo in your
modified file.
.aliases
This file allows you to assign longer, more complicated commands
to a single word. Within the file, use the following format:
alias <shortcut_name> "longer command"
For example, if you wanted to create a command called "web"
to create a file in your web space that is readable on the Internet,
you would add the following line to your .aliases file:
alias web "cd ~/.www && chmod 755"
To use the new alias open a new terminal and type the following
command:
web me.jpg
Executing this command will change the permissions of the
"me.jpg" file in your .www directory to 755 permissions.
.cshrc
The rest of the dot files are more complicated and can have drastic
effects on your X Windows environment. The .cshrc controls the
behavior of the csh shell (the default shell is tcsh, an updated
version of csh). Not only does this file control what modules are
loaded, but it also allows you to set a default printer or editor.
To locate the module information look for a line in your .cshrc that
looks like the following: "module load software1 software2
...". To add more modules to your environment, type the
following command:
module initadd <software>
After executing this command, the module name will be added to the
"module load" line, allowing it to be loaded every time
you log in. If you misspell the module name it can have inadvertent
effects on your X Windows environment. The best way to fix this
problem is to correct the module name in this section of .cshrc.
See the modules help page
for more information.
.fvwm2rc
This file controls the GUI that makes up your X Windows system. Two
window managers are currently supported: FVWM2 and Window Maker.
Both are controlled by the .fvwm2rc file. Editing .fvwm2rc is beyond
the scope of this help file, but what isn’t self-explanatory
can easily be found online.
.xinitrc
While the above three files are for configuration purposes, .xinitrc
is the only executable script. This file actually launches your
window manager when you log in. Use wmaker for Windows
Maker or fvwm2 for the older FVWM2. If there is a program
you want to launch every time you log in, enter it in .xinitrc
immediately before the fvwm2 or wmaker commands.
Repairing Your Dot Files
Although it is highly unlikely that your dot files can do anything
to permanently damage your data or your user account (unless you
code them to do just that), a misconfigured file can mess up X
Windows. In fact, the most common result of a badly designed
configuration is that you will not be able to log in at all. You
will know this is the case when the system recognizes your password,
starts logging in for a second or two, and then kicks you back to
the login screen. Luckily, there are some very easy ways to correct
this problem:
Edit the file directly
If you edited one of the above dot files and your X Windows
environment is now messed up, remove the changes you made. Your
account should now start fine.
Copy the default file back to your home directory
When you initialize your IT Labs account for the very first
time, your dot files are copied from the ~template
directory. If you know which dot file is causing the problem,
just copy that default version of the file from the ~template
directory to your home directory using the following command:
cp ~template/<name_of_screwed_up_file> ~/<name_of_screwed_up_file>
The '~' character by itself symbolizes your home directory while
'~template' symbolizes the home directory of the user
"template" (in this case, it is just a placeholder).
The tilde (~) is to the left of the number 1 on PC-style
keyboards and near the backspace on Sun keyboards.
Run resetenv
The most drastic--and most effective--way of fixing your dot
files is to run the following command:
opt/local/bin/resetenv
This script copies all of your current dot files to a backup
directory and then copies the default files from ~template into
your home directory. This effectively reverts your X Windows
system back to the defaults. Be sure to read the output from the
resetenv command carefully. It will tell you which dot files
have been set to the defaults and which ones have been kept the
same. It also tells you the directory where your old dot files
have been stored.
Of course, it is difficult to attempt any of these repairs if
the system will not let you log in to begin with. One way
around this is to SSH to
an IT Labs machine. This will allow you to log in to your Unix
account without starting the majority of your X Windows system.
You can run SSH from a computer in one of the Windows
labs or from most off-campus machines
that have an SSH client installed and are connected to the Internet.
If you need additional assistance, please contact the
systems operator.
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