Running a command for each line of a text file

Have you ever had a text file where each line holds, for example, a file name or a domain name, and for each of these lines you'd need to run a command to fetch some information or to do something with the file?

Well, the command is really simple. You just need to run a while loop from the command line.

Let's say we have an input file called sorgente.txt where each line holds our “variable”. Let's call output.txt the file that will hold the output we'd get on the command line for each of these lines. If, for example, we want to run the echo command to simply print the line of the text file, the loop will be this:

while read in; do echo "$in"; done < sorgente.txt > output.txt

so our command will be echo "$in", but we could replace it with any other command. The variable "$in" is our line of the text file read as input.

Try it with other commands and you'll see it saves you a ton of time! 🙂