Write in C the following Unix commands using system calls A). Guys, I am pretty new to C programming and this is the third week of class and we have already had this program as a project and it's due pretty soon like this Sunday. The cat command in Linux concatenate files and displays the output to the standard output (usually, the shell). The Grep command in Unix or Linux is a filter that is used to search for lines matching a specified pattern and print the matching lines to a standard output. But due to the -s command line option we used in the second cat command, the repeated empty lines got suppressed. The cat command is considered as one of the most frequently used commands on Linux or UNIX like operating systems. Reading Files How can I use cat command in UNIX or Linux shell scripts? Let's learn the Linux/Unix commands i.e. The cat command is termed “concatenate” which is one of the widely used commands in Unix/Linux & Apple Mac OS operating system. It has three related functions with regard to text files: displaying them, combining copies of them and creating new ones. Writing my own cat command . The version of cat bundled in GNU coreutils was written by Torbjorn Granlund and Richard Stallman.. Usage. Cat may refer to any of the following:. The cat command also allows you to display tab characters as ^I. The first command in the above screenshot shows all the empty lines that are there in the file. The options for the 'cat' command are as follows: -b Number the non-blank output lines, starting at 1. The cat command is used to concatenate files and display on the standard output (screen). $ cat sample.txt This is a sample text file To display content of all txt files. Linux Cat Command Usage with Examples. One of the most common uses of cat is to display a file to the screen and also to create a file on the fly and allow basic editing straight at the terminal. Implementing the 'cat' command. 8. The file created using touch command is empty. The name of the cat command comes from its functionality to concatenate files. cat sends its output to stdout (standard output), which is usually the terminal screen. History. The operator > can be used to combine multiple files into one. Copy text files into a new file. In this tutorial, you will learn most important commands for linux Command Line. How to Create a File Using 'cat' The cat command (short for “concatenate “) is one of the most frequently used command in Linux/Unix, Apple Mac OS X operating systems.cat command allows us to create single or multiple files, view contain of file, concatenate files and redirect output in terminal or files. cat sends its output to stdout (standard output), which is usually the terminal screen. It can read and concatenate files, writing their contents to the standard output. Normally you would copy a file with the cp command. 1. $ cat -s file6.txt. How can I use cat command in UNIX or Linux shell scripts?