Basic Linux Commands for beginners with example
1.Usage of Basic Linux Commands, File Utilities Commands.
|pwd||Present working directory|
|ls||Lists all files and directories in the present working directory|
|ls – R||Lists files in sub-directories|
|ls – a||Lists hidden files|
|ls – al||Lists files and directories with detailed information like permissions, size, owner, etc.|
|clear||Clears the terminal|
|whoami||Display User ID|
|uname||Display Operation System|
|tail <file name>||The tail command is similar to the head command. The difference between both commands is that it displays the last ten lines of the file content|
|find . -name “*.pdf”||The find command is used to find a particular file within a directory.|
|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)|
|tac <file name>||The tac command is the reverse of cat command, as its name specified. It displays the file content in reverse order (from the last line).|
|touch <file1> <file2>||Change the file access and modification time if file does not exist will create with default permission.|
|locate <file name>||The locate command is used to search a file by file name.|
|sort <file name>||The sort command is used to sort files in alphabetical order.|
|command | grep <searchWord> cat marks.txt | grep 9||The grep is the most powerful and used filter in a Linux system. The ‘grep’ stands for “global regular expression print.” It is useful for searching the content from a file. Generally, it is used with the pipe.|
|less <file name>||The less command is similar to the more command|
|mv <file name> <directory path>||Moves the files to the new location|
|mv filename new_file_name||Renames the file to a new filename|
|rm rfilename||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|
|cp <existing file name> <new file name>||Copy file|
|mkdir directoryname||Creates a new directory in the present working directory or a at the specified path|
|cd ..||Back one step current directory|
|rmdir||Deletes a directory|
|mv||Rename a directory|
|command | tr <‘old’> <‘new’> cat marks.txt | tr ‘prcu’ ‘PRCU’||The tr command is used to translate the file content like from lower case to upper case.|
|date||The date command is used to display date, time, time zone, and more.|
|time||The time command is used to display the time to execute a command.|
|cal||The cal command is used to display the current month’s calendar with the current date highlighted.|
|pr -x||Divides the file into x columns|
|pr -h||Assigns a header to the file|
|pr -n||Denotes the file with Line Numbers|
|head <file name> head demo.txt||The head command is used to display the content of a file. It displays the first 10 lines of a file.|
|tail <file name> tail demo.txt||The tail command is similar to the head command. The difference between both commands is that it displays the last ten lines of the file content.|
|wc <file name>||The wc command is used to count the lines, words, and characters in a file.|
|sudo||Allows regular users to run programs with the security privileges of the super user or root|
|sudo useradd username||Create New User|
|sudo -s||switch root user|
|sudo passwd username||Change user password|
|sudo apt-get update||Command used to install and update packages|
Listing files (ls)
Linux system, use the ‘ls ‘ command. It shows the files /directories in your current directory.
• Directories are show in blue color.
• Files are show in white.
• You will find similar color schemes in different flavors of Linux/Unix.
Your “Music” folder has following sub-directories and files.
‘ls -R ‘ to shows all the files not only in directories but also subdirectories
Note: These Linux basics commands are case-sensitive. If you enter, “ls – r ” you will get an error.
‘ls -al ‘ The command provides information in a columns format. The columns contain the following information:
Listing Hidden Files
Creating & Viewing Files
The ‘cat’ command is used to display text files. It can also combining and creating new text files. Let’s see how it works.
To create a new file, use the command
1. cat > filename
2. Press ‘ctrl + d ‘ Save File.
To view a file, use the command –
Let’s see the file we just created –
Let’s see another file sample2
The syntax to combine 2 files is –
cat file1 file2 > newfilename
Let’s combine sample 1 and sample 2.
To view the new combo file “sample ” use the command
Moving and Re-naming files
To move a file, use the command.
mv filename new_file_location
Suppose we want to move the file “sample2” to location /home/cse/Documents. Executing the command
mv sample2 /home/cse/Documents
[email protected]:~$ sudo mv sample2 /home/cse/Documents
[sudo] password for bz: ****
For renaming file:
mv filename newfilename
Directories can be created on a Linux operating system using the following command
Will create a directory ‘Music’ under ‘/tmp’ directory
You can also create more than one directory at a time.
will delete the directory mydirectory
mv directoryname newdirectoryname
The History Command
The clear command
This command clears all screen.
Assigning a header
pr -h “Header” Filename
The ‘-h’ options assigns “header” value as the report header.
As shown above, we have arranged the file in 3 columns and assigned a header
Display all lines with numbers
pr -n Filename
This command display all the lines in the file with numbers.