Editing Linux Basics Tutorial (section)

=== Special Bash Tools ===

The following symbols can help make working in Bash easier:

* '''!!''': Evaluates to the previous command you entered. You can also add on other text. So, for example, <code>$sudo !!</code> puts <code>sudo</code> before your previous command, and runs it. The use of <code>sudo</code> will be discussed later in this tutorial.

* '''&amp;''': Putting this at the end of a command will run that command in the background, meaning you will be able to keep using the same shell to do other commands, while the current command is still running. This is useful if you want to launch an application from the command line, but don't want to be locked out of Bash while it's running.

* '''&amp;&amp;''': This lets you run two commands in one. For example, <code>$ echo firstcommand &amp;&amp; echo secondcommand</code> will output the two arguments, each on its own line.

* '''>''': This will take the output of a command on its left, and put it into a file specified on its right. For example, <code>$ echo hi > tmp.txt</code> will put the word "hi" into the file tmp.txt, creating it if it doesn't exist.

* '''|''': This will take the output of a command on its left, run the command on the right, and feed that output into the right command's input. This is a more complicated one, but it's particularly useful for commands that look for "matches" of a pattern in some block of text, like <code>grep</code>.

* '''*''': This is the "wildcard" character, acting like a keyword that matches anything. For example, <code>$ rm *</code> will remove all files from your working directory. <code>$ rm *.txt</code> will only remove files ending in ".txt".