$ strace -fqeexecve perl -e 'open FH, "echo foo bar 2>&1 |"; print <FH>'
execve("/usr/bin/perl", ["perl", "-e", "open FH, \"echo foo bar 2>&1 |\"; "...], [/* 77 vars */]) = 0
[pid  1819] execve("/bin/echo", ["echo", "foo", "bar"], [/* 77 vars */]) = 0
foo bar