Beginner Linux Commands
Linux has a huge number of command line commands, here I will feature some of the most useful in my opinion.
To open a terminal window from the Desktop enter: Ctrl+Alt+t
Each command has options to modify the behavior. To learn about the function of a command and it’s options, the easy way is to type
man command to view the command’s manual documentation. Press q to exit.
We tend to type: command options parameters
For operations affecting files that we do not own as a user, we may prefix our command with
sudo if we have super user privileges.
Options are prefixed with a minus sign and multiple options may be combined after the minus sign (-xyz).
File system commands
List directory contents
Simple example: ls -la
-a include hidden files
-l provide detailed listing
-h output human-readable file sizes
-t sort by time
-r reverse sort order
-R list subdirectories recursively
-d list directories
If your colors are set up for your terminal, folder and file names should be displayed in different colors when listed. In Linux, file names do not have to have extensions.
You can specify a pattern for what to list with * meaning any character(s) e.g. ls *.txt
Print name of current/working directory
Home directory: ~/
Root of OS: /
Make a new empty file
Although, this command has other uses.
Create a new directory
-p make parent directories as needed for a deep path to a new directory.
Remove a file
-r remove directories and their contents recursively (drill down the tree)
-f force - ignore issues such as non-empty directories
-d remove empty directories
Copy files and directories
cp source destination
-a preserve settings such as read/write flags and owner.
-r copy recursively
-s create symbolic links instead of copying (the links point to the files but look like files in listings). Symbolic links might be used to enable features such as activated websites.
The destination of a file does not need to repeat it’s name, just the folder.
Move (rename) files
mv source destination
-n (no clobber) do not overwrite an existing file
-u update with new or newer file
This command is also used for renaming files e.g.
mv oldname newname
This is a powerful command that is useful for backing up files recursively, only copying changed files, copying over a network, or using a secure link with an ssh identity file.
Copy files to a server
Copy in archive mode (files that are new or changed), with verbose output, with file compression over the network, and delete files not in the source folder
rsync -avz --delete temp/* user@domain:/home/user/temp
user@domain would have been previously added to say the
~/.ssh/config file so that a password or identity file is already known.
Make a local backup
rsync -av files /mnt/backups/
This is useful for transferring a file securely over a network.
scp -i ~/.ssh/identity-file source destination
Locations on a server are specified with
user@domain:/path-on-server where domain may be the name in an ssh config file or the ip address of the server where the user has an account.
Report file system disk space usage
Download a file from the www
Download online videos
youtube-dl -r 330K url Limit the download rate to 330kB/s
Display file contents
To display varying amounts of larger files; check out
For individual files we use gzip and for bundles we use tar to make an archive file called a tarball.
Compress single file
gzip filename This produces filename.gz
-k keep original file
-d decompress file
Compress multiple files
tar -czvf filename.tar.gz path-to-files
To extract the files:
tar -xvf filename.tar.gz
And to change the location of where to extract the files:
tar -xvf filename.tar.gz -C \home\user\temp for example.
User and group commands
Show your user name and group memberships
Create a user
Modify a user account
List groups on system
We need to print the contents of a file using the
Create a new group
Change owner and group for a file or directory
sudo chown owner:group file
-R operate on files and directories recursively.
Change file permissions
sudo chmod mode file
This sets the permissions (read, write, execute) for the user (owner), group, or others. It is good practice to limit access based on permissions to only those that are in need of access to files.
The mode value is a set of 3 3-bit values read,write,execute for each type of access entity which may be expressed as octal numbers or abbreviations.
The values may be applied recursively, added individually, or removed etc.
man chmod for the full details.
Show system time and date
Reboot a server
Sometimes, when you login to a server, you are advised that a reboot is required.
Update package list
This is used on Ubuntu servers.
sudo apt update
And to upgrade the packages to the latest versions:
sudo apt upgrade
List running processes
Get a snapshot:
See realtime display of the processes:
Filter process list:
ps | grep -v grep | grep searchstring
The bar is used to “pipe” commands together.
grep is a filtering command. We filtered out the line containing the grep process in the above command.
To redirect command output to a file, we may use the > or » symbols to append the output.
ps > processfile
To stop a process from running, we take note of it’s ID from the listing of running processes and execute a
kill processID command.
Open file for editing in nano (may need sudo if outside of user home directory):
Save file: Ctrl-o
Exit nano: Ctrl-x
Erase line: Ctrl-k
For copy and paste, I have to use the right-click mouse context menu (Ctrl-c, Ctrl-v doesn’t seem to work in the linux terminal).
So hopefully that gets you started with the basics of the Linux command line, and be sure to bookmark this site and explore the other ever-expanding range of topics to be found here.