Re: Yes but I don't understand ...

[Igor Pechtchanski <pechtcha at cs dot nyu dot edu>]

On Tue, 5 Aug 2003, David Selby wrote:

> Randall R Schulz wrote:
>
> > David,
> >
> > At 12:28 2003-08-05, David Selby wrote:
> >
> >> I have hit a problem with bash ... as a sample program I have ...
> >
> >
> > Your problem is that /bin/sh is ash, not BASH. To get BASH, use /bin/bash
> >
> >
> >> #!/bin/sh
> >>
> >> Dave
> >
>
> You are dead right, I tried
>
> /bin/bash <script>
>
> and it worked perfectly, but I am afraid I do not understand why ...
> echo $BASH_VERSION
> Tells me I have bash

Yes, because it's inherited from the parent shell environment, most
likely (or you're running the above command from bash).  You do have bash
installed, but as /bin/bash, *not* /bin/sh.

> I call cygwin with ...
> c:\cygwin\win\rxvt.exe -e \bin\bash --login -i
> ie bash

Yes, you explicitly invoke bash.

> Where did ash (a stripped down bash?) come in ?
> Dave

When you have the #!/bin/sh line at the top of the script, you're asking
the current shell (bash, tcsh, whatever) explicitly to execute the script
using /bin/sh (which, on Cygwin, is ash).  If you want to ensure the
script is executed by bash, use the #!/bin/bash magic at the top of the
script.  Assuming that /bin/sh = bash is non-portable.
	Igor
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