Re: Shell for evaluating .SHELLFLAGS

[Afif Elghraoui]

On 05/26/2015 09:15 AM, David Boyce wrote:
> BTW /usr/bin/env creates a redundant process here. The reason people
> use /usr/bin/env to translate an execv() (does not use PATH) to an
> execvp() (does). But GNU make uses execvp() already; try "make
> SHELL=sh” to see that.
>
> -David Boyce

Thanks. That's good to know.

> On Tue, May 26, 2015 at 5:14 AM, Paul Smith <address@hidden> wrote:
> > On Mon, 2015-05-25 at 21:05 -0700, Afif Elghraoui wrote:
> > > SHELL=/usr/bin/env sqlite3
> > > .SHELLFLAGS=-init <(echo ".output $@") $(DB)
> > >
> > > I get this error:
> > > /bin/sh: 1: Syntax error: "(" unexpected
> > > Makefile:13: recipe for target 'fq' failed
> > >
> > > It looks like .SHELLFLAGS is evaluated with /bin/sh regardless of what
> > > SHELL is set to. Is there any way I could evaluate them with bash?
> >
> > You're missing the main point: the values of SHELL and SHELLFLAGS aren't
> > being evaluated by /bin/sh, or bash... they're not being evaluated by
> > any shell at all!

Fair enough. I guess I was further confused that my error message was 
coming from /bin/sh.


> > The entire point of setting SHELL is you're choosing a shell that make
> > will invoke.  Make does not use a shell to start the shell that you
> > requested: it invokes the shell you requested directly (using the exec()
> > system calls).

Got it.

> > The simplest way to do what you want is create a script (outside of
> > make) that will operate like this, then set SHELL in your makefile to
> > that script.  You can use #!/bin/bash at the top of that script to
> > request it be run in bash, if you like.

That works out really well. My Makefile header became:

SHELL=./sqlite-wrapper.bash
# The DB variable is defined in the top-level Makefile
.SHELLFLAGS=$@ $(DB)

and the wrapper script is:

#!/bin/bash
sqlite3 -init <(cat sqliterc <(echo ".output $1")) $2 "$3"

I added here another functionality I needed. I'm very glad that it works 
now.


Many thanks and regards
Afif

--
Afif Elghraoui
Laboratory for Pathogenesis of Clinical Tuberculosis Drug Resistance and 
Persistence
San Diego State University