[petsc-dev] Configure won't find python

[Jacob Faibussowitsch]

> command -v $pyimpls > /dev/null && echo Using: $pyimpl && exec $pyimpl "$@"

As Lisandro noted below, command -v would have to be swapped out since it also picks up aliases and doesn’t error out.

Also shouldn’t the final command sequence be “$pyimpl $0 $@“ so that it runs the configure script it was passed?

>> BTW, Are you aware of the behavior of `command -v` with shell aliases?
>> 
>> $ alias python=python3
>> $ command -v python
>> alias python='python3'

Best regards,

Jacob Faibussowitsch
(Jacob Fai - booss - oh - vitch)
Cell: (312) 694-3391

> On Apr 18, 2020, at 1:53 PM, Satish Balay <balay at mcs.anl.gov> wrote:
> 
> 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
>> 
>> 

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