Getting to know the command line: Linux CLI basics

Part 3. Active Server Management Commands

This is part will detail the commands that will allow you to actively make changes to your server. This includes how to move, copy, delete, zip, unzip and more.

CREATE A DIRECTORY

You can make (create) a directory with the mkdir command. To do this, you can either navigate to where you wish to create your new directory, or you create it using the full path.

For example, if you wanted to create an extra folder in your htdocs folder you could:

cd /var/www/yourwebsite.com/htdocs

And then:

mkdir mynewdirectory

Or you could create it with:

mkdir /var/www/yourwebsite.com/htdocs/mynewdirectory

CREATING NEW FILES

You can create a new file with the touch command. However, normally you’ll use nano filename.extension to create a file and open it with the nano editor at the same time. More information on this is in part 4.

An example using the touch command is:

touch newphpfile.php

COPY

You can create a copy of a file or folder with the cp command. This can come in very handy if you wish to make a copy of a file before editing, and it’s also useful for making certain Nginx changes persistent (you may see this in various other KB articles).

To use this command, you first type cp followed by the file you wish to make a copy of, followed by the desired location and filename of your copy. For example:

cp main-context.conf /_custom/main-context.conf

Think of the command like so:

cp SOURCE DESTINATION

Variables

Below are some useful variations of the cp command.

cp -f If there is already another file with the same name in the destination you’re copying to, this will override that file with the one you are copying.

cp -i This will give you a warning message before copying if a file with the same name already exists.

cp -n This will stop the copy from proceeding if there’s an existing file with the same name in the destination.

MOVE

The mv command will allow you to move files and directories from one place to another.

mv SOURCE DESTINATION

Variations

mv file.ext /dir/ This moves to the directory you specify.

mv file.ext/ .. This will move the file up one directory.

mv file.ext /dir/newname.text This variation will both move and also rename the file.

VIEWING THE CONTENTS OF EXISTING FILES

The following commands will allow you to view the contents of a file.

cat This will display the entire contents of a file. Example usage:

cat wp-config.php

Or you can use the whole destination:

cat /var/www/example.com/wp-config.php

head This will display the first 10 lines of a file. Example usage:

head wp-config.php

tail This will display the last 10 lines of a file. Example usage:

tail /var/www/example.com/wp-config.php

tail -f View a file in real-time. This is particularly useful for viewing logs while you’re running commands or using the vCanopy control panel to toggle things on and off. Here’s an example worth noting down:

tail -f /var/log/vCanopy.log

REMOVE (DELETE) STUFF

You can remove (DELETE) files and directories from your server with the rm command. This is where you need to start being careful as removing files and directories has real consequences that can/will affect your sites and servers. That said, it is still useful to know and will come in handy at some point down the line.

Here’s a simple example of removing a text file:

rm myoldfile.txt

You can also delete multiple files at once like this:

rm myoldfile1.text myoldfile2.text myoldfile3.txt

rm -r directoryname – This is a powerful command that can save a lot of time vs trying to do the same thing over SFTP. It will delete the directory and ALL of its contents. This means all sub-directories and files inside it.

So, for example, you could remove an entire website’s htdocs folder with:

rm -r /var/www/example.com/htdocs

Obviously, we don’t recommend you test that, but removing an entire htdocs folder can be handy for manual website migrations.

rmdir This command can be used to remove (delete) an empty directory. Example usage:

rmdir directoryname

VIEW FILE SIZES

The du (disk usage) command is great for checking how much disk space usage each of your websites and other files/directories are taking up on your servers. Used on its own usually isn’t going to be all that useful, but the variations below are well worth knowing.

Variations

du -h Displays results in human-readable format (bytes, KB, MB, GB etc).

du -sh Displays the grand total disk space of a directory in a human-readable format.

Here is a useful, more advanced command that you may wish to copy down. If you first navigate to the directory where all of your websites are stored with:

cd /var/www

This command will then list them by order of size (largest at the bottom), and display their size in human-readable format:

du -h --max-depth=1 | sort -h

VIEW SYSTEM DISK SPACE

With Monit installed on all servers, you won’t have much need for this command. You can view your disk usage any time by clicking on the pie chart icon next to each of your servers. However, it would be odd to leave it out, so you can check your system disk space usage with the df command.

Variations

df -h Displays results in a human-readable format.

df -T This will display system file types in an additional column.