Command:   tee - divert stdin to a file
Syntax:    tee [-ai] file ...
Flags:     -a  Append to the files, rather than overwriting
           -i  Ignore interrupts
Examples:  cat file1 file2 | tee x  # Save and display two files
           pr file | tee x | lpr    # Save the output of pr on x

     Tee copies stdin to standard output.  It also makes copies  on  all
the files listed as arguments.