Track with child processes

Trick copyright: The Book of Secret Knowledge <https://github.com/trimstray/the-book-of-secret-knowledge>

# 1)
strace -f -p $(pidof glusterfsd)

# 2)
strace -f $(pidof php-fpm | sed 's/\([0-9]*\)/\-p \1/g')

click the source code to copy install strace on any operating system with command-not-found.com