Department of Computing
Imperial College London
Linux setup files
Within your file space there are files that are important to the setup of
your account. These files are often known as 'dot' files because they are
named with a dot prefix in order to prevent them being removed accidentally
with any global remove commands.
Most can be configured by users but we recommend that you
do not touch these files, unless you know what you are doing (in
any case, you should always make a copy of the original first).
Files that are executed when you log in or out
- sourced when you first log in to a machine,
and thus tends only to act on your console window.
- executed by every shell that you run,
it configures aliases and sets environment variables.
Note that your .cshrc file should never generate output,
as this will break many things (for example remote execution of
commands via ssh).
- not essential, used to load applications automatically on an X-based terminal.
- not essential, executed on logout, it can be used to clean up temporay
files, remove Kerberos tickets, etc.
Files that help with security
- Your klogin is a list of trusted users who you will allow to login to
your account without needing a password. This uses the
Kerberos authentication system.
This file must be world readable. However, unless there are very specific
circumstances, .klogin is generally a bad idea. If you think you want to use
.klogin, read the above document, and also preferably
mail help and explain your circumstances.
- This is a file created when you login that allows applications to communicacte with your display. Without it, you will not be able to open new windows. Therefore - Do not touch this file! The file actually contains a key with which applications can talk to your display, for more information see
Files that tell people about you (optional)
- This file is appended to each mail you send, and to the bottom of each
post to Usenet News. It normally contains some information about yourself,
such as name and email address. It is generally considered bad
'netiquette' to have a .signature file longer than four lines.
- This file is displayed when somebody uses
finger to find information
- This file can be used to describe the work you are involved in.
Other important files
- This file contains your incoming email.
- These directories are created when a filesystem is browsed from a
Macintosh. In most cases they just contain the infomation needed
to support a consistent desktop view, e.g. icon locations, etc.
However, some Macintosh applications store data in the 'resource fork'
which lives in these directories so data could be lost if they are
Files that can be removed from your account
Through the normal use of your account extra files will be created some of
which can be safely deleted so as not to waste space. It is normal practice
for the Department to allocate more space than is physically available on the
system, since most users do not use up all of their
If nobody cleaned up their junk
files, space could quickly become short, it is therefore
a good idea to remove all junk files from your account.
- Any backup files. These are files created by editors, they contain the
old version of the edited file, and thus can normally be deleted. They usually
end in BAK, bak, #, or ~ but will vary according to your
- Any compiler created file.
Compilers tend to create lots of intermediate files (these usually end
in ".o") and
the binaries created can be very large as well. As long as the original
source code is still available, all these files can be deleted.
- Core files. These are very large files created for debugging
purposes when a program crashes (usually with a segmentation fault). They can
and should be deleted unless you intend to debug the program using the core
file. Alternatively, if you are running a shell which supports it, you can
disable the creation of core files by limiting their maximum size to zero.
You can do this (if you run
tcsh) by adding to
your .cshrc (or .tcshrc) file the line:
limit coredumpsize 0