×

This article covers how to use the uniq command in Linux. In fact, the uniq command reports or filters out repeated lines in a file. uniq filters out adjacent, matching lines from input file INPUT, writing the filtered data to output file OUTPUT. A matching line is "adjacent" if it's immediately before or after another matching line.



Related Linux commands:

  • comm — Compare two sorted files line by line.
  • pack — Compress files using a Huffman algorithm.
  • pcat — Print the uncompressed contents of a compressed file.
  • sort — Sort the lines in a text file.
  • uncompress — Extract files from compressed archives.



This article covers how to use the pkill command in Linux. pkill is basicity a wrapper around the pgrep program that only prints a list of matching processes.

The syntax for the pkill command is as follows:

$ pkill [OPTIONS] <PATTERN>

The matching <PATTERN> is specified using extended regular expressions.

For more information about pkill command, visit the pkill man page or type man pkill in your terminal.


Other Linux commands:

  • ps — Report the status of a process or processes.
  • killall — Kill processes by name.
  • kill — Send a signal to a process, affecting its behavior or killing it.



This article covers how to use head command with all required options. 

By using the tail command with a head command, you can also display the last lines of a file on the terminal.

The head command, as the name implies, print the top N number of data of the given input. 

By default, it prints the first 10 lines of the specified files. 

If more than one file name is provided then data from each file is preceded by its file name. 


Head command Syntax:

head [OPTION]... [FILE]...



This article covers how Wall command works in Linux. Wall is a handy utility that helps a multi-user system admin to quickly notify other users to save their work before a system shutdown or reboots. 

Here, you will see some examples of how to use the wall command to communicate with logged-in users.

There are times when multiple users are logged in to a server computer, and you - the system/network admin - need to, say, restart the server to perform some maintenance task. 

Of course, the correct way is to inform all those who are logged in about the maintenance activity.

In Linux, there is a built in command line utility for this purpose called Wall.


What is wall command in Linux ?

As already mentioned, the wall command is used to send a message to all logged in users. 

It's syntax is:

$ wall [-n] [-t TIMEOUT] [file]


How to use wall command?

Basic usage is very straight forward - just execute the 'wall' command and write the message you want to transmit on the standard input. 

Once done, use the Ctrl+D key combination to signal the command that you're done writing the message: 

$ wall


How to remove header from broadcasted message?

In case you want to remove the header that appears with the broadcasted messages, you can do that using the -n command line option:

$ wall -n



This article will guide you on the basic syntax and usage of the #grep #command in #Linux. We also went through some command-line options to expand its usefulness. The easiest of the two #commands is to use grep's -w option. This will find only lines that contain your target word as a complete word. 

Run the command "grep -w hub" against your target file and you will only see lines that contain the word "hub" as a complete word.

1. grep searches one or more input #files for lines that match a given pattern and writes each matching line to standard output. 

2. If no files are specified, grep reads from the standard input, which is usually the output of another command.



This article will guide you on how to use the #wc #command in #Linux. Here you will learn the basics of wc command along with its command-line options and few practical examples. Now you can easily count number of lines, words, characters and bytes in your files and in the output from other commands. The wc command in #UNIX is a command line utility for printing newline, word and byte counts for files. It can return the number of lines in a file, the number of characters in a file and the number of words in a file. It can also be combine with pipes for general #counting operations. To use use WC command, you need to know the following: wc -l : Prints the number of lines in a file. wc -w : prints the number of words in a file. wc -c : Displays the count of bytes in a file. 1. A Basic Example of WC Command. 2. Count Number of Lines. 3. Display Number of Words. 4. Count Number of Bytes and Characters. 5. Display Length of Longest Line.



This article will guide you on how to use the #cat #command to display or create a new file on #Linux. To save a file, you must first be in Command mode. Press Esc to enter Command mode, and then type :wq to write and quit the file. The other, quicker option is to use the keyboard shortcut ZZ to write and quit.



This article will guide you on using find command to find and remove files on your Server.



This article will guide you on how to add a new and existing user account to sudo in CentOS 8 by appending them to wheel group so that they can run admin commands.




More Linux Tutorials

We create Linux HowTos and Tutorials for Sys Admins. Visit us on IbmiMedia.com

Also for Tech related tips, Visit forum.outsourcepath.com or General Technical tips on www.outsourcepath.com