How to pipe a process' output to logger command and to head command?

Question

What I'm trying to do is:

• Start a process that outputs text continously

• Pipe that output to two commands:

  1. A logger script
  2. 'head' command, so I can save the first lines the initial process output.

What I tried so far (unsuccessfuly) is:

./myProgram | tee > (myLogger log.txt) | head > firstLines.txt

The problem is that the myProgram exits as soon as head is finished.

Even if I use -i in tee command, I can't get myProgram to keep running.

Since the logger may append the incoming text to an existing file, executing head log.txt > firstLines.txt won't work in this case.

Answer 1

You can use awk as an alternative to do both:

./myProgram | 
    awk 'NR<=10{print > "firstLines.txt"} NR>10{close("firstLines.txt")} 1' > log.txt

Answer 2

Like this maybe:

yes | awk 'FNR<4 {print >>"file"; close("file")}  1' | more

where yes is your program, file is where you send the output of head to, and more is your logger.