[petsc-dev] Configure won't find python

[Satish Balay]

Well I prefer different scripts.

We used to have patch files encoded in python [it was bad].

We still make syntax and shell syntax encoded in python - and that has its own quirks.. [wrt extra care when editing etc :(]

Satish

On Sat, 18 Apr 2020, Jed Brown wrote:

> Who says configure can't be both a shell script and a Python script?
> 
> 
> diff --git i/configure w/configure
> index 4538314871..969a9c0a36 100755
> --- i/configure
> +++ w/configure
> @@ -1,4 +1,11 @@
> -#!/usr/bin/env python
> +#!/bin/sh
> +
> +"true" '''\'
> +for pyimpl in python3 python python2; do
> +  command -v $pyimpl > /dev/null && echo "Using $pyimpl for Python" && exec $pyimpl "$0" "$@"
> +done
> +exit 127
> +'''
>  
>  import sys, os
>  
> 
> 
> https://rosettacode.org/wiki/Multiline_shebang#Python
> 
> 
> Satish Balay via petsc-dev <petsc-dev at mcs.anl.gov> writes:
> 
> > I guess this is an alternate way to implement this logic..
> >
> > diff --git a/configure b/configure
> > index 4538314871..8dddfed05d 100755
> > --- a/configure
> > +++ b/configure
> > @@ -1,4 +1,4 @@
> > -#!/usr/bin/env python
> > +#!./python-detect
> >  
> >  import sys, os
> >  
> > diff --git a/python-detect b/python-detect
> > new file mode 100755
> > index 0000000000..1fdfe795c8
> > --- /dev/null
> > +++ b/python-detect
> > @@ -0,0 +1,6 @@
> > +#!/bin/sh
> > +for pyimpl in python3 python2 python ; do
> > +   command -v $pyimpls > /dev/null && echo Using: $pyimpl && exec $pyimpl "$@"
> > +done
> > +echo “Could not locate python! Please have python3 python2 or python in PATH
> > +exit 2
> >
> >
> > Satish
> >
> > On Fri, 17 Apr 2020, Jacob Faibussowitsch wrote:
> >
> >> Hello All,
> >> 
> >> I use an Ubuntu docker image based on jedbrown/mpich-ccache and ran into the following error (Dockerfile attached as well).
> >> 
> >> If in a user only has python3 installed and not python2 then /usr/bin/python doesn’t exist. Given that python2 has gone the way of the dodo perhaps petsc should be looking for python3 over python2. This is a somewhat funky but functioning implementation that replaces the shebang line in configure that I have been using to default to python3. I don’t know how portable it is however, I believe “command" is not universally available in every shell?
> >> 
> >> #!/bin/sh
> >> 
> >> # “”” is comment in python, and : is noop in shell so this configure can be run as ./configure and python2.7 ./configure
> >> """:"
> >> 
> >> # Find the right python implementation, check by sending it on over to dave
> >> for pyimpls in python3 python2 python /usr/bin/python /usr/bin/env python ; do
> >>    command -v > /dev/null $pyimpls && exec $pyimpls $0 "$@“
> >> done
> >> 
> >> # Error code in case things go awry
> >> 
> >> Echo “PYTHON NOT FOUND” >2
> >> 
> >> exit 2
> >> 
> >> ":"""
> >> 
> >> if sys.version_info < (2,6) or (sys.version_info >= (3,0) and sys.version_info < (3,4)):
> >>   print('************************************************************************')
> >>   print('*      Python version 2.6+ or 3.4+ is required to run ./configure      *')
> >>   print('*         Try: "python2.7 ./configure" or "python3 ./configure"        *')
> >>   print('************************************************************************')
> >>   sys.exit(4)
> >> 
> >> sys.path.insert(0, os.path.abspath('config'))
> >> import configure
> >> configure.petsc_configure([])
> >> 
> >> 
> >> Best regards,
> >> 
> >> Jacob Faibussowitsch
> >> (Jacob Fai - booss - oh - vitch)
> >> Cell: (312) 694-3391
> >> 
> >> 
>