Bourn Shell -n Flag Questions

[Lowell Gilbert]

Martin McCormick <martin at dc.cis.okstate.edu> writes:

> 	I read about the noexecute flag or -n flag which is supposed
> to check the syntax of a Bourn Shell script to see what it would do if
> run, but not actually do anything.  This sounds like a wonderful
> thing, especially when one is going to run a dangerous script and you
> only get one chance to get it right.
> 
> 	I tried sh -n scriptname and it always silently succeeds even
> if I type sh -x -n somescript.  I even deliberately created a script
> with a syntax error in it and tried sh -x -n again.  It still did
> nothing but exit.  Does this just not work or am I misunderstanding
> the purpose of the flag?

I don't know where you checked the syntax of the Bourne Shell, but
FreeBSD's /bin/sh (which although not actually derived from Steve
Bourne's code does a pretty good job of covering the POSIX
requirements for sh, and a bunch of useful additions as well) is
specific to noninteractive use.  According to its manual, anyway.