Importing environment variables set by batch file in parent Perl script

Question

I am writing a cross-platform build script in Perl for code compilation.

In Windows, I need to execute vsvars32.bat to set the environment variables:

sub set_win_env {
      #MSVC version 9.0 is installed
      $VS90COMNTOOLS = $ENV{'VS90COMNTOOLS'};
      $VS90COMNTOOLS .= "vsvars32.bat"
      if($VS90COMNTOOLS ne "") {
          system("$VS90COMNTOOLS");
      }
 }

The environment variables set by executing the batch files gets lost as interpreter spawns another shell to execute the batch file.

How can I import those variables in the parent Perl script?

BTW, how a variable can be an empty string after being concatenated with a constant string? The condition is always true. — choroba
– choroba, Commented Nov 5, 2012 at 12:44
yeah useless check... initially i was appending the variable after the check... :) — Dexter
– Dexter, Commented Nov 5, 2012 at 12:49

choroba · Accepted Answer · 2012-11-05 13:09:30Z

1

If your BAT file is simple (i.e. it only contains lines of the form VAR=VALUE), you can parse it by Perl. If there is something more going on (some values are calculated from others etc.), just output all the variable names and their values at the end of the BAT script in the form VAR=VALUE.

The parsing of the simple format is easy:

while (<$BAT>) {
    chomp;
    my ($var, $val) = split /=/, $_, 2;
    $ENV{$var} = $val;
}

answered Nov 5, 2012 at 13:09

choroba

245k27 gold badges221 silver badges304 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Dexter Over a year ago

I tried reading the batch file in form of key=value. However, it seems that the batch file(its a msvc file) has values of the form %VAL%=<path>:%VAL%. In this case i am not bale to read the correct and complete values. And i cannot modify the batch file. only can read that,

cdarke · Accepted Answer · 2012-11-05 13:03:49Z

1

As you say, using system will set the environment variables in the child process, not in the current process. The problem is that you have a file in '.bat' format, which is a different language to Perl (OK, maybe calling it a language is a bit strong).

You need to either parse the file yourself and translate it into Perl, or, run your perl from a .bat file which has (for example):

CALL "C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\vcvarsall.bat" amd64
perl perlscript.pl

answered Nov 5, 2012 at 13:03

cdarke

44.8k8 gold badges85 silver badges86 bronze badges

Collectives™ on Stack Overflow

Importing environment variables set by batch file in parent Perl script

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related