Redirect only the last line of STDOUT to a file

Question

I\'m compiling Scala code and write the output console output in file. I only want to save the last line of the STDOUT in a file. Here is the command:

scalac         


        

Answer 1

You could use tail:

scalac -Xplugin:divbyzero.jar Example.scala | tail -1 >> output.txt

Answer 2

scalac ... | awk 'END{print>>"output.txt"}1'

This will pipe everything through to stdout and append the last line to output.txt.

Answer 3

Just pipe stdout through tail -n 1 to your file

Answer 4

Just a small precision regarding this tail command. If the program output on standard error, you have to redirect it

Example:

apachectl -t 2>&1 | tail -n 1

Redirections: http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html

Answer 5

In Bash and other shells that support process substitution:

command | tee  >(tail -n 1 > outputfile)

will send the complete output to stdout and the last line of the output to the file. You can do it like this to append the last line to the file instead of overwriting it:

command | tee  >(tail -n 1 >> outputfile)