Most Linux sysadmins will know this little trick for redirecting standard output and standard error (i.e. ‘all’ output from a command) to a file:
make &> /tmp/build.log
However, sometimes you’ll want to monitor the output on the screen as well as redirecting to a file. For example, when I’m building a big program I want to keep my eye on where things are up to, but I also want a copy sent to a file so I can examine it if there are any errors. I could open a second terminal and run tail on the file, but there’s a more elegant solution:
make 2>&1 | tee /tmp/build.log
The tee command reads from standard input and writes to standard output and a file. So in the above pipeline we’re saying:
- Redirect standard error to standard output (
2>&1). - Pipe standard output to the standard input of
tee. - Display standard input on standard output and write it to a file.
Tee is part of the GNU coreutils package, so it should be installed by default on pretty much every Linux system.