On 17/05/2011 21:27, Karen Tung wrote:
> Hi Jack,
>
> Having to invoke Python everytime I want to read a variable in the shell
> script
> sounds very
> "heavy weight" to me, especially when we want to use a lot of variables in the
> shell script.
>
> What about the following solution?
>
> 1) Define the values in Python
> 2) Create a Makefile target to extract all the predefined values
> from the python file and put them into into a file that can be included by
> shell
> scripts
> that need to use those values.
> 3) Deliver both the Python definition file, and this generated file in a
> package.
I think that this makes a lot of sense, and the approach looks good to me.
>
> This way, we can still have values defined in 1 central location,
> but we don't need to invoke Python multiple times from a shell script.
>
Yes, running python multiple times or even once at the start of a shell script
does seem excessive - if for no other reason that it restricts the environment
that a shell script can be run in by adding a direct Python dependency.
Thanks,
Darren.
> Thanks,
>
> --Karen
>
>
> On 05/16/11 13:45, Jack Schwartz wrote:
>> Hi everyone.
>>
>> A few weeks ago I suggested removing definitions which were duplicated
>> between
>> python and shell files. One organized way of doing this is to put
>> definitions
>> into a Python file and have shell scripts run python in a commandline mode to
>> extract them. Python files, of course, can just import the definitions. I
>> prototyped this as follows:
>>
>>
>> --- usr/src/lib/install_common/common_defs.ksh --------------
>>
>> # Can be added to installadm-common.sh
>>
>> #!/bin/ksh
>>
>> # getdef: Get a definition from a python file.
>> #
>> # Args:
>> # definition name
>> # Returns:
>> # definition value
>> #
>> function getdef
>> {
>> in_arg="import common_defs as defs; print defs.${1}"
>> out_arg=$(/usr/bin/python -c "$in_arg" 2>/dev/null)
>> if [[ $? -ne 0 ]]; then
>> return 1
>> fi
>> print $out_arg
>> return 0
>> }
>>
>>
>> --- usr/src/lib/install_common/common_defs.py -------------
>>
>> #!/bin/python2.6
>>
>> # File full of definitions to share...
>>
>> LOGFILE="/system/volatile/install_log"
>> MANIFEST="/system/volatile/manifest.xml"
>>
>>
>> --- begin shell.ksh -----------------------------------------
>>
>>
>> #!/bin/ksh
>>
>> # A shell script that needs a shared (Python) definition.
>>
>> . commondefs.ksh
>>
>> LOGFILE=`getdef "LOGFILE"`
>> if [[ $? -ne 0 ]] ; then
>> echo "Error getting LOGFILE definition"
>> else
>> echo "Logfile is $LOGFILE"
>> fi
>>
>> -------------------------------------------------------------
>>
>> Does this sound like something worthwhile? If so, I'll take the initiative
>> to
>> ferret out duplicates and implement the above.
>>
>> Are there suggestions to improve implementation? Please let me know.
>>
>> A few caveats: I suggest excluding error messages from these common defs, as
>> if they are not accessible, a misleading error message could be displayed
>> instead of the real cause.
>>
>> I didn't consider C since we are getting away from using it. I can look into
>> a joint python/shell/C effort if needed.
>>
>> Thanks,
>> Jack
>>
>>
>> _______________________________________________
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>> http://mail.opensolaris.org/mailman/listinfo/caiman-discuss
>
>
>
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