Apologies, my earlier email, item 2, pointed to emptyenv as the cause of
zombie processes on FreeBSD 12.2S, actually it is due to background.
# execlineb -Pc 'background { echo hello } pipeline { ps -axw } grep
defunct'
hello
30144 0 Z+ 0:00.00 <defunct>
while the following tests both foreground and emptyenv
# execlineb -Pc 'emptyenv foreground { echo hello } pipeline { /bin/ps
-axw } /usr/bin/grep defunct'
hello
#
Software revision level (as available in the FreeBSD ports system)
execline-2.6.0.1
s6-2.9.1.0
s6-rc-0.5.1.2
skalibs-2.9.2.1
Further detail:
# execlineb -Pc 'emptyenv background { echo hello } pipeline { /bin/ps
-axwwdo pid,ppid,stat,command } /usr/bin/grep -B1 "defunct"'
hello
71212 70760 Ss | | `-- -csh (csh)
16885 71212 S+ | | `-- /usr/bin/grep -B1 defunct
17052 16885 Z+ | | |-- <defunct>
I've also placed a ktrace and kdump of
execlineb -Pc 'ktrace -f /tmp/bgnd.kt /usr/local/bin/background {
/bin/ps } echo a'
here
http://www.heuristicsystems.com/s6/
