Linux Command List

 

 Linux Command List

Below is a Cheat Sheet of Linux commands list we have learned in this Linux commands tutorial

Command	Description
ls	Lists all files and directories in the present working directory
ls - R	Lists files in sub-directories as well
ls - a	Lists hidden files as well
ls - al	Lists files and directories with detailed information like permissions, size, owner, etc.
cat > filename	Creates a new file
cat filename	Displays the file content
cat file1 file2 > file3	Joins two files (file1, file2) and stores the output in a new file (file3)
mv  file "new file path"	Moves the files to the new location
mv filename new_file_name	Renames the file to a new filename
sudo	Allows regular users to run programs with the security privileges of the superuser or root
rm filename	Deletes a file
man	Gives help information on a command
history	Gives a list of all past basic Linux commands list typed in the current terminal session
clear	Clears the terminal
mkdir directoryname	Creates a new directory in the present working directory or a at the specified path
rmdir	Deletes a directory
mv	Renames a directory
pr -x	Divides the file into x columns
pr -h	Assigns a header to the file
pr -n	Denotes the file with Line Numbers
lp -nc lpr c	Prints "c" copies of the File
lp -d lpr -P	Specifies name of the printer
apt-get	Command used to install and update packages
mail -s 'subject' -c 'cc-address' -b 'bcc-address' 'to-address'	Command to send email
mail -s "Subject" to-address < Filename	Command to send email with attachment

 

 

• Each file in Linux has a corresponding File Descriptor associated with it
• The keyboard is the standard input device while your screen is the standard output device
• ">" is the output redirection operator. ">>" appends output to an existing file
• "<" is the input redirection operator
• ">&"re-directs output of one file to another.
• You can re-direct error using its corresponding File Descriptor 2.
•  
• Pipes '|' send the output of one command as input of another command.
• The Filter takes input from one command, does some processing, and gives output.
• The grep command can be used to find strings and values in a text document
• Piping through grep has to be one of the most common uses
• 'sort' command sorts out the content of a file alphabetically
• less ,pg and more commands are used for dividing a long file into readable bits

• Regular expressions are a set of characters used to check patterns in strings
• They are also called 'regexp' and 'regex'
• It is important to learn regular expressions for writing scripts
• Some basic regular expressions are:

Symbol	Descriptions
.	replaces any character
^	matches start of string
$	matches end of string

• Some extended regular expressions are:

Expression	Description
\+	Matches one or more occurrence of the previous character
\?	Matches zero or one occurrence of the previous character

• Some interval regular expressions are:

Expression	Description
{n}	Matches the preceding character appearing 'n' times exactly
{n,m}	Matches the preceding character appearing 'n' times but not more than m
{n, }	Matches the preceding character only when it appears 'n' times or more

• \]The brace expansion is used to generate strings. It helps in creating multiple strings out of one.