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Determining the type of environment entry from Perl

From: Ole Tange
Subject: Determining the type of environment entry from Perl
Date: Wed, 17 Jul 2013 14:53:28 +0200

GNU Parallel can today successfully transfer bash environment values
through ssh to the remote host:

   export FOO
   parallel --env FOO -S server 'echo $FOO' ::: bar

But I would like to be able to transfer functions, too. Right now they
work locally:

    myfunc() {  echo This is a func: $1
    export -f myfunc
    parallel myfunc ::: bar

But through ssh they do not work:

    $ parallel -S server myfunc ::: bar
    bash: myfunc: command not found

    $ parallel --env myfunc -S server myfunc ::: bar
    bash: line 2: myfunc: command not found

I have managed to get the function definition copied correctly:

    $ parallel --env myfunc -S server echo '$myfunc' ::: bar
    () { echo This is a func: $1 } bar

And I can even assign the definition back:

    $ parallel --env myfunc -S server eval myfunc'"$myfunc"'\;myfunc ::: bar
    This is a func: bar

The problem is that from inside GNU Parallel I cannot tell whether
myfunc is a function or a simple variable, and doing the eval above on
simple values give the wrong results. Here are 3 tricky environment

    d() {  echo This is a func: $1
    e='() {  echo This is not a func but it looks like one: $1
    g='() {  echo This is not a func and it even misses the final
curly brace: $1 '
    export -f d
    export e
    export g

How do I from Perl see which of these are functions and which are not? I tried:

    perl -e 'print qx(bash -c "type -t e")'
    perl -e 'print qx(bash -c "type -t d")'
    perl -e 'print qx(bash -c "type -t g")'

But they fail horribly if $g is set:

    $ perl -e 'print qx(bash -c "type -t e")'
    bash: g: line 1: syntax error: unexpected end of file
    bash: error importing function definition for `g'

If $g is not set they just give the wrong result:

    $ perl -e 'print qx(bash -c "type -t d")'
    function # Correct
    $ perl -e 'print qx(bash -c "type -t e")'
    function # Wrong



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