HintsAndTips.html

---
layout: lesson
root: .
title: Hints and tips
---

<h2>Getting help about a command - <code>man</code> pages</h2>
<p>
Type:
</p>
<pre>
$ man COMMAND
</pre>
<p>
For example:
</p>
<pre>
$ man ls
$ man grep
$ man git
</pre>
<p>
The up and down arrows on your keyboard allow you to scroll up and down the page.
</p>
<p>
To exit from the <code>man</code> page, press <code>q</code>.
</p>

<h2>Auto-completion</h2>
<p>
Bash shells support what is called <em>tab completion</em>. If you type part of a command or file name, then press TAB, it will show the commands or files that match that prefix of the command. For example, if you type:
</p>
<pre>
$ gre
</pre>
<p>
then, without pressing ENTER, you press TAB you should see something like
</p>
<pre>
$ gre
greadelf  grep           grepjar
grefer    grep-changelog
</pre>
<p>
which are all the commands that match <code>gre</code>. This also works for files. For example, if you type:
</p>
<pre>
$ ls dat
</pre>
<p>
then, without pressing ENTER, you press TAB you should see a list of all the files that start with <code>dat</code>. If there is only one, then the file name will be auto-completed e.g.
</p>
<pre>
$ ls data.txt
</pre>

<h2>Command history, or avoid having to retype commands</h2>
<p>
Bash shells support a command history - they record every command you type in. If you use up-arrow, or <code>CTRL-P</code>, at the command prompt you can scroll back to the previous command you executed. Down-arrow, or <code>CTRL-N</code>, allows you to scroll to the next command.
</p>
<p>
You can then move the cursor and edit the command. To move the cursor in the line you can do:
</p>
<ul>
<li>Left, <code>CTRL-B</code></li>
<li>Right, <code>CTRL-F</code></li>
<li>To the start of the line, <code>CTRL-A</code></li>
<li>To the end of the line, <code>CTRL-E</code></li>
</ul>
<p>
If you enter:
</p>
<pre>
$ history
</pre>
<p>
You'll see a list of the commands in the history. Each has a number. If you enter:
</p>
<pre>
$ !NNN
</pre>
<p>
where <code>NNN</code> is the number of a command in the history, that command will be rerun.
</p>
<p>
To search for a command that you've run before you can do:
</p>
<pre>
$ history | grep "COMMAND"
</pre>
<p>
For example:
</p>
<pre>
$ history | grep "ls"
</pre>

<h2>A quick-start guide to the <code>nano</code> editor</h2>
<p>
nano is a simple text editor for Linux/Unix.
</p>
<p>
To start:
</p>
<pre>
$ nano file.txt
</pre>
<p>
To move the cursor:
</p>
<ul>
<li>Left, <code>CTRL-B</code></li>
<li>Right, <code>CTRL-F</code></li>
<li>Up a line, <code>CTRL-P</code></li>
<li>Down a line, <code>CTRL-N</code></li>
<li>To the start of the line, <code>CTRL-A</code></li>
<li>To the end of the line, <code>CTRL-E</code></li>
</ul>
<p>
To delete and undelete a line:
</p>
<ul>
<li>Delete the current line, <code>CTRL-K</code></li>
<li>Undelete the recently deleted lines, <code>CTRL-U</code></li>
</ul>
<p>
To save a file, <code>CTRL-O</code>. You will be given the opportunity to edit the file name to save the file under a different name.
</p>
<p>
To quit, <code>CTRL-X</code>. If the file has unsaved changes you'll be given the chance to save them now.
</p>