What Is a Linux Command?

A Linux command is a program or utility that runs on the CLI – a console that interacts with the system via texts and processes. It’s similar to the Command Prompt application in Windows.

Here’s what a Linux command’s general syntax looks like:

CommandName [option(s)] [parameter(s)]

A command may contain an option or a parameter. In some cases, it can still run without them. These are the three most common parts of a command:

• CommandName is the rule that you want to perform.

• Option or flag modifies a command’s operation. To invoke it, use hyphens (–) or double hyphens (—).

• Parameter or argument specifies any necessary information for the command.

Keep in mind that all Linux commands are case-sensitive.

Listing commands

• ls option_flag arguments --> List the sub-directories and files available in the present directory.

• ls -l--> List the files and directories in a long list format with extra information

  

• ls -a --> List all including hidden files and directories.

  

• ls *.sh --> List all the files having .sh extension

  

• ls -i--> List the files and directories with index numbers Inodes.

  

• ls -d */ --> list only directories.(we can also specify a pattern)

  

Directory commands

• pwd --> Print work directory. Gives the present working directory.

  

• cd path_to_directory --> Change the directory to the provided path

  

• cd ~ or just cd --> Change the directory to the home directory

  

• cd - --> Go to the last working directory.

  

• cd .. --> Change the directory to one step back.

  

  Mkdir Examples:

• mkdir FolderSK --> Make a new folder 'new folder'.

  

• mkdir .HideMe --> Make a hidden directory (also . before a file to make it hidden).

  

• mkdir A B C D --> Make multiple directories at the same time.

  

• mkdir /home/user/Mydirectory --> Make a new folder in a specific location.

  

• mkdir -p A/B/C/D --> Make a nested directory.

  

Commonly Used Linux commands:

sudo (command)       #lets you perform tasks that require administrative or root permissions.

pwd [option]         #To find path of your current working directory

cat filename.txt.    #It lists, combines, and writes file content to the standard output.

cp filename1.txt filename2.txt    #to copy files or directories and their content.

touch /home/username.html     #to create an empty file or generate and modify a timestamp in the Linux command line.

locate -i school*note   #find a file in the database system.

grep blue notepad.txt   #to find a word by searching through all the texts in a specific file.

df -h     #to report the system’s disk space usage, shown in percentage and kilobyte (KB).

du /home/user/Documents  #to check how much space a file or a directory takes up

head note.txt         # to view the first ten lines of a text

tail -n colors.txt      #to displays the last ten lines of a file.

diff note.txt note_update.txt       #the diff command compares two contents of a file line by line.

tar -cvf newarchive.tar /home/user/Documents    #archives multiple files into a TAR file – a common Linux format similar to ZIP, with optional compression.

chmod 777 note.txt #to modifies a file or directory’s read, write, and execute permissions.

kill SIGKILL 63773    # to terminate an unresponsive program manually.

ping google.com     #for checking whether a network or a server is reachable.

wget https://wordpress.org/latest.zip       # lets you download files from the internet

Thanks for reading my article. Have a nice day.

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