Basic HTML version of Foils prepared Sept 20 97

Foil 70 Processing the Environment %ENV

From Tutorial on PERL Computational Science for Information Age Course CPS616 -- Sept 20 97. by Geoffrey C. Fox,Nancy McCracken,Tom Scavo


1 %ENV is set as the shell environment in which the Perl program was invoked
2 Any UNIX processes invoked by system, fork, backquotes, or open inherits an environment specified by %ENV at invocation of child process
3 One can change %ENV in the same way as any hash:
4 %ENVIN = %ENV ; $oldpath = $ENV{"PATH"}; # saves input environment
5 $ENV{"PATH"} = $oldpath . ":/web/cgi"; # resets PATH to include an extra directory to be used by child process -- later we run
6 %ENV=%ENVIN; # Restores original environment
7 One can see what has been passed in %ENV by using Perl keys function
8 foreach $key (sort keys %ENV ) {
9 print "$key = $ENV{$key}\n"; # both $key, $ENV{} are interpolated
10 }

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