===== Linux Command Line Basics =====

There are a number of good resources on the web. Here's one of them:

[[http://linuxcommand.org/index.php]]

==== Commands you should know ====

=== Changing Your Password ===

Note: this does not apply to users who log in with their Unity Id and password.

<code>
passwd
</code>

There is a 12-character minimum length requirement on the cluster.

=== Navigation ===

<code>
pwd - print working directory
ls - list files
cd - change directory
less - file pager
file - describes type of a file
</code>

=== File Manipulation ===

<code>
cp - copy 
mv - move (rename)
rm - remove (delete)
mkdir - make directory
rmdir - remove directory
</code>

=== Editing Text ===

Choose an editor:

<code>
nano
vi
emacs
</code>

=== Basic Script ===

<code>
#!/bin/bash
...
</code>

Make a script file "executable":

<code>
chmod u+x scriptname
</code>

=== Getting More Information ===

<code>
man COMMAND
man ls
</code>

=== IO Redirection ===

Save output from a command to file.

<code>
ls > file.txt
</code>

=== Terminal Multiplexing ===

This lets you run multiple terminals that are immune to "hang-ups" (network errors) and can remain active even after you log out. You "detach" from the terminal and then re-attach after logging back in.

<code>
screen
</code>

Other terminal multiplexers (byobu, tmux) are also installed on the cluster.

=== Finding Files ===

Find a file by name:

<code>
find . -name lost_file.txt
</code>

**find** is a very flexible (and quite complicated) tool for finding files and applying commands to the results. It's well worth learning more about this command.

=== Disk Space Use ===

Calculate the total size of a directory:

<code>
du -sh dirname
</code>