Using dash as default /bin/sh would cause privileged_startx fail

[LdBeth]

Symbol link /bin/dash to /private/var/select/sh to change default /bin/sh as dash shell (to reproduce the issue probably needs a reboot, since it may be related to some scripts that was run at boot) seems would cause a cryptic error message when startx or any time executing /op/X11/libexec/privileged_startx:

privileged_startx: client: (os/kern) failure

Although most people won't change the default setting of using /bin/bash as the sh, for people exploring the probability of reducing bashism on their systems this is a risk they should know.

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This is tested with Monterey v12.6.2 (21G320) on Intel MacBook，affecting all recent release versions of XQuartz from 2.8.2 to 2.8.5-beta

[jeremyhu]

I'm glad to see folks making use of /private/var/select/sh to switch to dash. I didn't really do much other than add the sh(1) man page to advertise it. Thanks for helping to make scripts more portable.

checkbashisms is a great tool if you haven't discovered it yet: https://salsa.debian.org/debian/devscripts.git