Problem with Bash output redirection

Question

I was trying to remove all the lines of a file except the last line but the following command did not work, although file.txt is not empty.

$cat file.txt |ta         


        

Answer 1

You can use sed to delete all lines but the last from a file:

sed -i '$!d' file

• -i tells sed to replace the file in place; otherwise, the result would write to STDOUT.
• $ is the address that matches the last line of the file.
• d is the delete command. In this case, it is negated by !, so all lines not matching the address will be deleted.