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Re: values from perl to sh script

by pbeckingham (Parson)
on Jul 14, 2005 at 17:41 UTC ( #474983=note: print w/ replies, xml ) Need Help??


in reply to values from perl to sh script

I would say print them to STDOUT, and capture them in the shell script. Alternatively use a file.



pbeckingham - typist, perishable vertebrate.


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Re^2: values from perl to sh script
by wpeterma (Initiate) on Jul 14, 2005 at 18:02 UTC
    Once perl has written the values to STDOUT, what do I use to read them in to the script? Is it read? (Sorry for being a rank amateur)
      Capture them into a variable, something like
      RESULT=`perl runme.pl`
      Then your result will be in $RESULT

      Updated: Those are backticks surrounding the perl script

      Don
      WHITEPAGES.COM | INC
      Everything I've learned in life can be summed up in a small perl script!
      Nevermind, I have it. I an exporting my variables to env, then the script has them. e.g echo ${ENVVAR} Thanks for your consideration.
        If the Perl program is started from your shell script and you want to let it return data to that shell script, setting environment variables won't do you any good. A child process (the Perl program) cannot alter it's parent's (ht e shell script) environment!

        Paul

      (Some of the following notes surely apply to bash, don't know about other shells).

      You can use the backtick operator or its equivalent (and prefearable, IMHO):

      return1=`/path/to/script.pl arg1 arg2` return2=$(/path/to/script.pl arg1 arg2)
      The latter has the added advantage of allowing nested subshell invocations.

      If your return value can have newlines, I'd suggest to use double quotes:

      return_newlines="$(/path/to/script.pl arg1 arg2)"
      And yes, you can use read as well, but you have to be extremely careful about what you want to do. Suppose you have the following script:
      #!/usr/bin/perl print $_, $/ for @ARGV;
      and you want to set the variable value to the contents of the last line:
      #!/bin/bash value=0 echo "value starts from $value" ./script.pl arg1 arg2 | while read line ; do value=$line echo "value is $value" done echo "after first while, value is $value" while read line ; do value=$line echo "value is $value" done <<<"$(./script.pl arg1 arg2)" echo "finally, value is $value"
      you obtain:
      value starts from 0 value is arg1 value is arg2 after first while, value is 0 value is arg1 value is arg2 finally, value is arg2
      Note that after the first while the variable value has not been modified. This is due to the fact that the first while cycle is being executed inside a subshell.

      OTOH, the second while is executed directly by the "current" shell. This may lead to problems if you pass a lot of data back, anyway.

      Note that there are also other ways, but there is too little space on the side of this post to write them.

      Flavio
      perl -ple'$_=reverse' <<<ti.xittelop@oivalf

      Don't fool yourself.

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