On Wed, Apr 30, 2014 at 04:39:28PM -0400, Chet Ramey wrote: > On 4/30/14, 4:34 PM, Viktor Szépe wrote: > > echo first $$ >&2 | bash -c 'echo second $$' > > first 30551 > > second 28057 > > > > but > > > > eval 'echo first $$' >&2 | eval 'echo second $$' > > first 30551 > > second 30551 > > $$ doesn't change in a subshell environment. It changes in your first > example because you're starting a new shell instance.
In bash 4.0 and higher, you can use the BASHPID variable to get the process ID of a subshell. $$ always gives the process ID of the main shell. echo "main $$ $(echo "subshell $BASHPID")"
