Some useful tools that I have found.
Pipes
Tee
Named after a plumbing “T” junction, tee allows us to pipe the output of a command to be redirected to two different commands, or to an output file and the screen.
Examples:
# 1. redirect output to screen (stdout) and a file
ls -la | tee output.txt
# 2. redirect output to a file and another command
ls -la | tee output1.txt | head
# 3. redirect output to two different files
ls -la | tee output1.txt | awk '{print $1}' > output2.txt
# It can be useful for creating backup files
cat myfile.txt | tee myfile.bak | sed...
Sponge
Part of the moreutils package.
Sponge delays a file’s modification, by creating a temporary buffer that allows using the same file as both input and output of a pipe.
For example:
cat myfile.txt | awk '{print $1}'> myfile.txt
does not work, because “myfile.txt” gets overwritten before awk is finished processing it. The normal way around it is to write the output to a temporary file, then replace the original file with the temporary.
On the other hand, we could use sponge:
cat myfile.txt | awk `{print $1}` | sponge > myfile.txt