Re: [Help-bash] bash to csh converter?

[Mun]

Hi Bob,

On Tue, Mar 22, 2016 at 08:09 PM PDT, Bob Proulx wrote:
BP> Mun wrote:
BP> > I'm wondering if the issue with this script stems from that fact that it
BP> > must be sourced (in order to update the user's environment variables)?
BP> > We have other bash scripts which do not require to be sourced and those
BP> > run correctly when launched from a csh environment.
BP> 
BP> Yes.  That you are trying to source these scripts is a critical piece
BP> of information.  In the sense that the rest of us are talking about
BP> those are not really standalone scripts, which is why we were talking
BP> about the #! lines.
BP> 
BP> Sourced scripts ignore #! lines because those are simply comments to
BP> the shell reading it at that point.  Source scripts are explicitly
BP> interpreted by the current shell, as it was instructed to do.
BP> Therefore the syntax must of course be compatible syntax with the
BP> current shell.

Ah, okay.  That makes sense.

BP> The bash documentation says this (the same is true for csh and other
BP> shells too):
BP> 
BP>        source filename [arguments]
BP>               Read and execute commands from filename  in  the  current  
shell
BP>               environment ...
BP> 
BP> > GW> If this is what you're experiencing, the fix is to put the correct
BP> > GW> shebang on your script.  Every time.
BP> > 
BP> > I wish it were that easy, but that is not my problem.
BP> 
BP> Agreed.  But it is only with this email that we have arrived at what
BP> was actually the problem.

Sorry about that.  This thread kind of took a turn from what I had originally
intended and thus I failed to provide essential details.

BP> > Since it seems that a script or program is not available to convert our
BP> > bash scripts to csh, I will look into why this bash script that must be
BP> > sourced is behaving badly when executed from a csh environment.
BP> 
BP> AFAIK there isn't any automated conversion available.  I don't think
BP> it is possible in the completely 100% case.  Maybe possible in a
BP> restricted subset of typical script syntax.  Probably.
BP> 
BP> I have been in similar situations as you are now in needing to set
BP> environment variables from a different shell syntax of csh and ksh.
BP> Here is what I did in that case.  This is off the top of my head.  I
BP> will try testing it later and updating if I miss type but the concept
BP> is valid regardless.
BP> 
BP>   exec tcsh -c 'source environ.csh; exec bash'
BP> 
BP> First I exec csh to replace the current shell with tcsh.  Then in that
BP> shell it is instructed to source the environment setting script.  That
BP> script sets and exports to the environment all of the environment
BP> variables as needed by the task specific command environment.
BP> (Corporate CAD/EDA tools by any chance?)  Then after having sourced

Yes, EDA :)

BP> that and exported those environment variables then I exec bash again
BP> to replace the current csh with bash.  The exported environment
BP> variables are now in my current bash command line environment.  I can
BP> then proceed to run the CAD tools as needed.
BP> 
BP> Make sense?  Try that technique and see how it works for you.  It's a
BP> hack but a useful one considering the other constraints.  This is for
BP> the command line.  Could be set up as a bash alias.  But if you try to
BP> do this automatically at login time from the bash .profile or .bashrc
BP> it will need somewhat different special handling.

Yes, your technique does make sense.  I'll try that out.  Thanks for the
detailed explanation.

Best regards,

-- 
Mun