Overview
While cPanel & WHM automates many server administration tasks, familiarity with the Linux® command line can prove useful for both WHM and cPanel users. This documentation gives a brief overview of some basic Linux commands that you may wish to use as you manage your website or server.
Note: For steps to access the command line, read our How to Access the Command Line documentation.
Common Linux commands
Note:
- To execute a command, enter the command with any options or arguments that it requires and press Enter.
- In the following examples, replace filename with the relative path to the file that you wish to view.
The following lists some basic Linux commands and their functions:
| Command | Description |
|---|---|
man $command |
This will be the most important command. "man" will provide you with the manual page on a specific command so that you can read a more detailed description, view all options and learn about the proper usage for a command. man rm |
cat filename |
Print the contents of the specified file to the CLI. Replace cat filename.txt Note: To view the data that currently displays on your server’s console screen, run the following command:
cat /dev/vcs1 |
less filename |
View the contents of a file. Replace less filename.txt Note: less can also be used to view output piped into it from other commands. For example, to view the output of a ps -faux|less |
cd location |
Navigate between directories. Replace location with the path to the directory that you wish to navigate to. For example, to navigate to the cd /usr/local/apache/
|
chmod permissions filename |
Change a file’s octal permissions. Replace permissions with the three-digit octal permissions that you wish to grant to the file, and replace filename with the relative path to the file for which you wish to alter the permissions. For example, to change the permissions of the myfile.txt file to 755, run the following command:
chmod 755 myfile.txt
Note: For more information, read the Wikipedia article about the
chmod command. |
chown user:group filename |
Change a file’s user and group ownership. Replace user with the user to whom you wish to grant ownership of the file, group with the group name, and filename with the relative path to the file. For example, to grant the user joe in the group joesgroup ownership of the joesfile.txt file, run the following command:
chown joe:joesgroup joesfile.txt
|
cp file1 file2 |
Copy a file into a new file. Replace file1 with the relative path to the existing file, and file2 with the relative path to the new copy file that you wish to create. For example, to copy the contents of the original.txt file to the /copies/duplicate.txt file, run the following command:
cp original.txt /copies/duplicate.txt
|
du |
Show the system’s current disk usage for each directory and subdirectory. Can be limit to only show subdirectories at a certain depth with the --max-depth option. du --max-depth=1 |
file filename |
Guess a file’s type, based on the file’s contents. Replace filename with the relative path to the file for which you want the system to guess the type. For example, to cause the system to guess the type for the example.txt file, run the following command:
file filename
|
grep string filename |
Search for a string in a specified file, and prints each line that contains a match to the CLI. Replace string with a single word, or multiple words within single quotes (''). Replace filename with the relative path to the file that you wish to search. For example, to search for the string coffee filters in the grocerylist.txt file, run the following command:
grep 'coffee filters' grocerylist.txt
|
last |
List which users recently logged in and the timestamp for each login. |
ln -s file1 file2 |
Create a symbolic link between the two specified files. Replace file1 with the relative path to the existing file, and file2 with the relative path to the new symbolic link file. For example, to create the symlink-file.txt file and point it to the /pointtome/file.txt file, run the following command:
ln -s /pointtome/file.txt symlink-file.txt
|
ls |
List files and directories that exist within your current directory. This command resembles the dir command in Windows®. To view dotfiles (filenames that begin with a period) and additional file and directory details, add the -al options to the command:
ls -al
|
more filename |
Print the contents of a file to the CLI, one screen at a time. Replace filename with the relative path to the file that you wish to view. For example, to print the contents of the filename.txt file one screen at a time, run the following command:
more filename.txt
|
netstat |
List all of the server’s current network connections. |
pico filename |
Open the specified file in the pico text editor. Replace filename with the relative path to the file that you wish to edit. For example, to open the filename.txt file in the pico editor, run the following command:
pico filename.txt
|
ps |
Return information about the server’s current processes. To view all of the running processes, run one of the following commands:
ps -auxww ps -cef
|
mv /path/current_file /path/new_file |
This command can be used to rename files or move files from one location to another |
rm filename |
Delete the specified file. After you run this command, the system prompts you to confirm the file’s deletion. Replace filename with the relative path to the file that you wish to delete. For example, to delete the trash.txt file, run the following command:
rm trash.txt
|
tail filename |
Print the last 20 lines of a file to the command line interface (CLI). Replace filename with the relative path to the file that you wish to view. For example, to print the last 10 lines of the filename.txt file, run the following command:
tail filename.txt
You can add an argument to change the number of lines that this command prints. For example, to print the last 100 lines of the filename.txt file, run the following command:
tail -100 filename.txt
|
touch filename |
Create an empty file in the specified location. Replace filename with the relative path to the file that you wish to create. For example, to create an empty example.txt file, run the following command:
touch example.txt
|
vi filename |
Open the specified file in the vi text editor. Replace filename with the relative path to the file that you wish to edit. For example, to open the filename.txt file in the vi editor, run the following command:
vi filename.txt
|
w |
List currently logged-in users and the location from which they logged in. |
wc filename |
Display the word count for a specific file. Replace filename with the relative path to the file for which you wish to view a word count. For example, to display a word count for the example.txt file, run the following command:
wc example.txt
|
whereis name |
Query applications that match the name value. You can find the most common applications in the following locations:
|
find /path/to/search/ |
Print the contents of the directory, including the contents of directories inside the directory, and so on. Can be used to find specific files with the -name option. find /path/to/search/ -name filename |
Run multiple commands on the same line
Various command-line tasks may require that you use different commands on the same line. Linux includes easy methods to perform these tasks.
- Use the pipe character (|) to retrieve data from one program and "pipe" it to another program.
- Use a single greater-than bracket (>) to create a new file if the file does not already exist, or to overwrite any existing content if the file does exist.
- Use a double greater-than bracket (>>) to create a new file if the file does not already exist, or to append the new data to the file if the file does exist.
- Use a single less-than bracket (<) to send input from a file to a command.
The following lists examples of how to combine tasks into a single line:
| Command | Description |
|---|---|
grep User /usr/local/apache/conf/httpd.conf | more
|
This command searches for all of the lines in the httpd.conf file that match the user search term, and then prints the results to your terminal one screen at a time. |
last -a > /root/lastlogins.tmp
|
This command prints all of the current login history to the /root/lastlogins.tmp file. |
mysql --skip-column-names --batch -e 'show processlist' | wc -l
|
This command lists the number of MySQL threads. If subselect expressions start new threads, the output of the show processlist command includes them. |
netstat -an | grep :80 | wc -l
|
This command shows the number of active connections to Apache (Apache’s httpd daemon runs on port 80). |
tail -10000 /var/log/exim_mainlog | grep 'example.com' | more
|
This command finds the last 10,000 lines from the
Note: The system treats periods (
.) in a command as wildcard characters. Precede each period with a backslash (\) to instruct grep to interpret the period literally. |
Common configuration files can be found in our documentation.