On 9/29/16 11:49 PM, Martijn Dekker wrote: > I detected an oddity (possible bug) in bash: the usual optimisation for > launching external processes in simple command substitutions is turned > off while executing a dot script. > > Background: For reasons that would take too much space to explain here, > I need a cross-platform/POSIX way to get the process ID of the current > subshell. I can't use $BASHPID for this as it's only available on newer > bash (not including the default bash on Mac OS X). > > As far as I know, the canonical cross-platform way of detecting the PID > of a subshell is: > > my_subshell_pid=$(sh -c 'echo $PPID') > > This works fine on every shell, except on bash when a dot script is > being executed.
This isn't a bug. It can be viewed as an opportunity for further optimization. Rather than assume an implicit `exec', make your assumption explicit and use something like `exec sh -c 'echo $PPID''. -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/