This is part of the Semicolon&Sons Code Diary - consisting of lessons learned on the job. You're in the unix category.
Last Updated: 2024-04-25
sponge is a non default command available via the moreutils package
It's key feature is that it waits for pipe to finish rather than streaming
echo "Put this text in a file" | sponge file1.txt
# Streaming equivalent with just built-ins
echo "Put this text in a file" > file1.txt
This features comes in handy when we want to read and write from a file in the same pipeline without data corruption
grep -v '^#' cities.txt > cities.txt
# grep: input file ‘cities.txt’ is also the output
Most people would get around with a tmp file
grep -v '^#' cities.txt > /tmp/cities.tmp
mv /tmp/cities.tmp ./cities.txt
But this is annoying
Enter sponge
grep -v '^#' cities.txt | sponge cities.txt