On Wed, Jun 07, 2017 at 01:52:57PM +0200, Joerg Schilling wrote: > Jilles Tjoelker <jil...@stack.nl> wrote:
> > In interactive mode, job control (-m) is enabled automatically. Some > > shells, such as FreeBSD sh, dash, mksh and heirloom-sh-050706, allow > > starting an interactive shell without job control using sh +m, while > > other shells, such as bash and ksh93, do not (the option is ignored). > After Stephane pointed to the POSIX standard that includes the same > text as the ksh man page, I implemented to auto-enable -m in the POSIX > Bourne Shell (bosh) for interactive shells. > While doing this, I discovered that the Burne Shell first parses the > command line options and later decides whether the current shell is > interactive. For this reason, I do not see that it would be possible > to use "sh +m" in a useful way. It is possible to make a distinction between options that are false because they are explicitly turned off and options that are false because they have not been mentioned. > BTW: given that heirloom-sh-050706 is a mostly unmodified Bourne Shell > from OpenSolaris, it also first parses the options and later decides > whether it is interactive. So even if it did auto-enable (it does not) > -m, > heirloom-sh-050706 +m > would be a no-op with respect to the monitor flag. In my observation it is not a no-op (check the PGID fields): jilles@lion /home/jilles% jsh $ ps jT USER PID PPID PGID SID JOBC STAT TT TIME COMMAND jilles 1501 1499 1501 1501 0 Ss 7 0:00.06 zsh jilles 1505 1501 1505 1501 1 S 7 0:00.00 jsh jilles 1506 1505 1506 1501 1 R+ 7 0:00.00 ps jT $ % jilles@lion /home/jilles% jsh +m $ ps jT USER PID PPID PGID SID JOBC STAT TT TIME COMMAND jilles 1501 1499 1501 1501 0 Ss 7 0:00.06 zsh jilles 1507 1501 1507 1501 1 S+ 7 0:00.00 jsh +m jilles 1508 1507 1507 1501 1 R+ 7 0:00.00 ps jT $ % jilles@lion /home/jilles% This is heirloom-sh-050706 from the FreeBSD package, which has only one source code patch, to turn off shell accounting. -- Jilles Tjoelker
