tee — pipe fitting
tee [-ai] [file …]
The tee utility copies standard input to standard output, making a copy in zero or more files. The output is
The following options are available:
-a Append the output to the files rather than overwriting them.
-i Ignore the SIGINT signal.
The following operands are available:
file A pathname of an output file.
The tee utility takes the default action for all signals, except in the event of the -i option.
The tee utility exits 0 on success, and >0 if an error occurs.
The tee function is expected to be POSIX IEEE Std 1003.2 (“POSIX.2”) compatible.