server_ip=192.168.1.100 username=admin password=old_password The task is to update the password setting to new_password in all files that contain this setting. Alex learns about the sed command, which stands for "stream editor." sed is a powerful tool for modifying text files without having to open them in a text editor.

sed 's/old_password/new_password/' config.txt The s command in sed stands for "substitute." It searches for the pattern old_password and replaces it with new_password . Running the sed command produces the following output:

#!/bin/bash

Meet Alex, a system administrator who needs to modify a large number of configuration files on a Linux server. The files contain a specific setting that needs to be updated, but there are hundreds of files to change. Manually editing each file would be a tedious and time-consuming task. That's when Alex discovers the power of the sed command. The Problem Alex has a file called config.txt with the following contents:

sed 'expression' file.txt In this case, Alex wants to replace old_password with new_password in the config.txt file. The sed command to achieve this is:

server_ip=192.168.1.100 username=admin password=new_password As you can see, the password has been updated successfully. By default, sed outputs the modified text to the console. To edit the file in-place, Alex uses the -i option:

sed -i 's/old_password/new_password/' config.txt This command updates the original file config.txt with the new password. What if Alex needs to update the password in multiple files? sed can handle that too:

Setedit Command (2027)

#!/bin/bash

sed 'expression' file.txt In this case, Alex wants to replace old_password with new_password in the config.txt file. The sed command to achieve this is: Running the sed command produces the following output: #