[petsc-dev] Configure won't find python

[Jed Brown]

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
>> 
>>