Bourn Shell -n Flag Questions

	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?

	Thanks for your help.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Network Operations
Group
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Hello,

Bourne shell is bash. So you should try
bash -n scriptname



--
N. Ersen SISECI
http://www.enderunix.org




On 4/28/06, Martin McCormick <martindc.cis.okstate.edu> wrote:
>         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?
>
>         Thanks for your help.
>
> Martin McCormick WB5AGZ  Stillwater, OK
> Systems Engineer
> OSU Information Technology Department Network
Operations Group
> _______________________________________________
> freebsd-questionsfreebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-que
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Martin McCormick <martindc.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.
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> On 4/28/06, Martin McCormick <martindc.cis.okstate.edu> wrote:
> 
>>         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?
>>
>>         Thanks for your help.
>>
N. Ersen SISECI wrote:
 > Hello,
 >
 > Bourne shell is bash. So you should try
 > bash -n scriptname

Um, "Bourne shell" is /bin/sh.  "Bourne
Again SHell" is bash, which is 
not installed in FreeBSD by default.

As for "sh -n", consider:

[343] Fri 28.Apr.2006 19:35:03
[kadminarchangel][~/scripts]# cat foobaz
#!/bin/sh

PRE="Foo
ECHO=/bin/echo
TARGET=/tmp/foobar

$ECHO $PRE > $TARGET

[344] Fri 28.Apr.2006 19:35:20
[kadminarchangel][~/scripts]# sh -n foobaz
foobaz: 3: Syntax error: Unterminated quoted string

So, it would appear that "-n" is merely a
"lint" type option or "syntax 
checker".  Whether or not it's smart enough to catch
your error I can't 
tell; it caught mine with and without "-x" ....

HTH,

Kevin Kinsey

-- 
The giraffe you thought you offended last week is willing to
be nuzzled
today.
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