[Gambas-user] Exec statement not working though equivalent Terminal command works

[Fabien Bodard]

I think the f8 argument is parsed by the app Tobias
Le 9 juil. 2014 11:50, "Tobias Boege" <taboege at ...626...> a écrit :

> On Wed, 09 Jul 2014, John Rose wrote:
> > I have this code:
> >      Print "mplex", "-f 8", "-o " & "'" & sCombinedPath & "'", "'" &
> > sVideoPath & "'", "'" & sAudioPath & "'"
> >      Exec ["mplex", "-f 8", "-o " & "'" & sCombinedPath & "'", "'" &
> > sVideoPath & "'", "'" & sAudioPath & "'"] To sOutput
> > I'm using the single quotes since they are required when entering the
> > equivalent commands in a Terminal e.g. mplex   -f 8    -o
> > '/home/john/Videos/q.mpg'    '/home/john/Videos/The Story of Science_
> > Power, Proof____20140621_2000.m2v' '/home/john/Videos/The Story of
> > Science_ Power, Proof____20140621_2000.mp2'.
> >
> > The Print statement shows (at runtime):
> > mplex   -f 8    -o '/home/john/Videos/q.mpg' '/home/john/Videos/The
> > Story of Science_ Power, Proof____20140621_2000.m2v'
> > '/home/john/Videos/The Story of Science_ Power,
> Proof____20140621_2000.mp2'
> > i.e. the exact equivalent of the working command when entered in a
> > Terminal.
> >
> > However, the Exec statement does nothing at runtime, though the
> > equivalent Terminal command works. There is no feedback on why by
> > Gambas. I've also tried the statements without the single quote usage &
> > it also did nothing. I'm fairly sure that this used to work on the
> > previous version of Gambas: I'm using kendek's Gambas3 ppa
> > (https://code.launchpad.net/~nemh/+archive/ubuntu/gambas3) which
> > installed Gambas 3.5.3. The code without the single quote usage is:
> >      Print "mplex", "-f 8", "-o " & sCombinedPath, sVideoPath, sAudioPath
> >      Exec ["mplex", "-f 8", "-o " sCombinedPath, sVideoPath, sAudioPath]
> > To sOutput
> >
> > The above sOutput variable has the value "". What I am doing wrong or is
> > it an issue in Gambas 3.5.3?
> >
>
> The fundamental thing to remember is: Exec is way not the terminal/shell.
>
> The shell needs you to quote your arguments in different manners so that it
> can see where actual spaces are and where spaces belong to, e.g., file
> names. The space is a control sequence for the shell - not for Exec! In
> Exec, you must not quote stuff because the data you give is literally
> transferred into the kernel. If you write Exec ["program", "'file name'"],
> the kernel will look for a file literally named 'file name', the
> apostrophes
> being part of that file name!
>
> Just make sure that each argument is in its own array element; that is
> enough for Exec.
>
> This applies also to "-f 8" where you put two arguments into one array
> element. You'll confuse the program's command line parser because it does
> not know the switch "-f 8", it just knows the switch "-f" which may be
> followed by an argument "8", a *distinct* argument.
>
> To sum up, I'm pretty sure your Exec line should be like:
>
>   Exec ["mplex", "-f", "8", "-o", sCombinedPath, sVideoPath, sAudioPath]
>
> Regards,
> Tobi
>
> --
> "There's an old saying: Don't change anything... ever!" -- Mr. Monk
>
>
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