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Environment variables in Perl / use Env

If I say use Env;, Perl loads in a module which allows me to access all my environment variables directly within my code, by name. If I add an explicit list of variable names as a list to the module, then only those variables will be imported. So in this example, $PATH prints nothing but $SHELL and $PWD tell you the shell and the present working directory. Extra environment variables can be accessed directly from the %ENV hash (and that can be done whether or not you have called the module in).

# Env brings environment into current namespace
use Env qw(SHELL PWD);
 
print "--- $PATH ---\n";
print "--- $SHELL ---\n";
print "--- $PWD ---\n";
 
print "--- $ENV{PATH} ---\n";

(written 2008-07-11, updated 2008-07-12)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
P210 - Perl - Topicalization and Special Variables
  [4700] Obfurscated code - it might work, but is it maintainable? - (2016-07-02)
  [4682] One line scripts - Awk, Perl and Ruby - (2016-05-20)
  [4395] Preparing data through a little bit of Perl - (2015-01-15)
  [4301] Perl - still a very effective language indeed for extracting and reporting - (2014-09-20)
  [3449] Apache Internal Dummy Connection - what is it and what should I do with it? - (2011-09-19)
  [2972] Some more advanced Perl examples from a recent course - (2010-09-27)
  [2876] Different perl examples - some corners I rarely explore - (2010-07-18)
  [2833] Fresh Perl Teaching Examples - part 2 of 3 - (2010-06-27)
  [1922] Flurinci knows Raby Lae PHP and Jeve - (2008-12-04)
  [1860] Seven new intermediate Perl examples - (2008-10-30)
  [1829] Dont bother to write a Perl program - (2008-10-10)
  [1728] A short Perl example - (2008-07-30)
  [1704] Finding operating system settings in Perl - (2008-07-10)
  [1508] How not to write Perl? - (2008-01-15)
  [1444] Using English can slow you right down! - (2007-11-25)
  [1289] Pure Perl - (2007-08-03)
  [1232] Bathtub example - (2007-06-14)
  [1221] Bathtubs and pecking birds - (2007-06-07)
  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [969] Perl - $_ and @_ - (2006-12-07)
  [639] Progress bars and other dynamic reports - (2006-03-09)
  [493] Running a Perl script within a PHP page - (2005-11-12)

P211 - Perl - Hashes
  [3662] Finding all the unique lines in a file, using Python or Perl - (2012-03-20)
  [3451] Why would you want to use a Perl hash? - (2011-09-20)
  [3400] $ is atomic and % and @ are molecular - Perl - (2011-08-20)
  [3106] Buckets - (2010-12-26)
  [3072] Finding elements common to many lists / arrays - (2010-11-26)
  [3042] Least Common Ancestor - what is it, and a Least Common Ancestor algorithm implemented in Perl - (2010-11-11)
  [2920] Sorting - naturally, or into a different order - (2010-08-14)
  [2915] Looking up a value by key - associative arrays / Hashes / Dictionaries - (2010-08-11)
  [2836] Perl - the duplicate key problem explained, and solutions offered - (2010-06-28)
  [1917] Out of memory during array extend - Perl - (2008-12-02)
  [1856] A few of my favourite things - (2008-10-26)
  [1826] Perl - Subs, Chop v Chomp, => v , - (2008-10-08)
  [1334] Stable sorting - Tcl, Perl and others - (2007-09-06)
  [968] Perl - a list or a hash? - (2006-12-06)
  [930] -> , >= and => in Perl - (2006-11-18)
  [738] (Perl) Callbacks - what are they? - (2006-05-30)
  [386] What is a callback? - (2005-07-22)
  [240] Conventional restraints removed - (2005-03-09)


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