What is the use of the following command in Unix shell scripting?Command:ls . | sed ’s/\.MKV$/\.mp4/’

The command ls . | sed ’s/\.MKV$/\.mp4/’ in Unix shell scripting is used to list all the files in the current directory and then replace the extension of the files from .MKV to .mp4. Here's a step-by-step breakdown:

1. ls . : This command lists all the files in the current directory.

2. | : This is a pipe. It takes the output of the command on its left and uses it as the input for the command on its right.

3. sed ’s/\.MKV$/\.mp4/’ : This is a sed command, which is a stream editor for filtering and transforming text. The s is for substitute command, \.MKV$ is the regular expression that matches any line ending with .MKV, and \.mp4 is the replacement for matched line.

So, the whole command is used to replace the .MKV extension of files to .mp4 in the output of the ls . command. However, it's important to note that this command only changes the display in the terminal and does not actually rename the files in the directory.