Date: Fri, 28 Feb 2003 18:32:37 GMT From: abc@dialups-247.anchorage.mtaonline.net To: Giorgos Keramidas <keramida@ceid.upatras.gr> Subject: Re: #!/bin/sh & execve Message-ID: <200302281832.h1SIWbSp046258@en26.dialups-247.anchorage.mtaonline.net>
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> > the method used by FBSD 2.2.7 seems the most sane to me,
> > where execve's argv[] is loaded by each whitespace
> > seperated element after the shebang,
> > then by command line options.
> >
> > 1. it is flexible.
> > 2. it functions intuitively.
> > 3. i don't think it breaks less flexible methods.
>
> It also suffers from problems with arguments that are meant to include
> spaces, like:
>
> #!/bin/sh "hello world" "foo bar"
>
> Without a fully functional sh(1)-like parser, any solution that does
> magic with argv[] is incomplete :-(
Apologies for a delayed response.
This concerned how to load execve()'s argv[] array
when parsing the 'shebang' line of a script, ie:
whether to pass everything after '#!/interpeter'
1. as one string into execve()'s argv[] array, as some systems do, or
2. as individual arguments, as exist after #!/interpreter, separated
by whitespace.
Bug report 16383 showed the variance in the various UNIX's
of how this is done. Orginal SysV specs say to load '1 argument'
only after #!/interpreter, leaving it ambiguous as to whether
the '1 argument' is the 1st whitespace separated argument,
or whether it is everything after #!/interpreter as one string.
Posix and SUSv3 don't say anything about how to load execve()'s
argv[] array after #!/interpreter, and seem to leave it to
"whatever is the most intelligent way".
I suggested it made more sense as FBSD 2.2.7 used to do it,
where execve()'s argv[] array was loaded contiguously with
whitespace separated elements, so one could use constructs
such as "#!/bin/sh /script-preprocessor options", and to
allow "#!/interpreter opt1 opt2" and "#!/interpreter opt1 arg1"
type constructs, things that intuitively work as one would
expect on a command line, since there didn't appear to be
any penalty for allowing this flexibility.
A plausible argument was given in response:
> #!/bin/sh "hello world" "foo bar"
I repond as follows: that's something only a Windoze user would think of
doing! :) Unix users don't put whitespace in filenames, nor would they create
options to programs that contain whitespace. Also, to load:
'"hello world" "foo bar"'
as one string, breaks it's purpose anyway. it is a bizarre example that has
little practical value, and can be easily compensated for by getting rid of
whitespace in a filename, in the bizarre case where it may exist as such.
Finally, to be slightly extreme with a tiny performance penalty, a beginning
and ending quote in a string could be check for and respected by execve()'s
code that fills argv[].
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