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(1) quotes in PERL
Following types of quotes are there with their different meanings;
(a) Single quotes ('')
Single quotation marks are used to enclose data you want taken literally.
#!/usr/bin/perl -w
use strict;
my $value;
$value = 7;
my $check = 'it is worth $value';
print $check;
#prints it is worth $foo
(b) Double quotes ("")
Double quotation marks are used to enclose data that needs to be interpolated before processing.
#!/usr/bin/perl -w
use strict;
my $value;
$value = 7;
my $check = "it is worth $value";
print $check;
#prints it is worth 7
(c) Escape Characters (\\)
#!/usr/bin/perl -w
use strict;
my $value;
$value = 7;
my $check = "it is \"worth"\ $value";
print $check;
#prints it is "worth" 7
(d) Quoting without quotes
There are three simple methods of doing this with the letter q.
In the following three sections, on the subjects of q, qq, and qw notation.
(i) q
The first way to quote without quotes is to use q() notation.
#!/usr/bin/perl -w
use strict;
my $foo;
my $bar;
$foo = 7;
$bar = q(it is 'worth' $foo);
print $bar;
# print it is 'worth' $foo
(ii) qq
In the same way that double-quotes add interpolation to the functionality of single-quotes, doubling the q adds interpolation to quoting without quotation marks.
#!/usr/bin/perl -w
use strict;
my $foo;
my $bar;
$foo = 7;
$bar = qq(it is "worth" $foo);
print $bar;
# print it is "worth" 7
(iii) qw
You can use qw to quote individual words without interpolation.
@baz = ('one', 'two', 'three');
@baz = qw(one two three);
(iv) here documents
If you want to quote many lines of text literally, you can use "Here Document" notation. This consists of an introductory line which has two open angles (aka "angle brackets": << ) followed by a keyword — the end tag — for signalling the end of the quote.
#!/usr/bin/perl -w
use strict;
my $foo = 123.45;
my $bar = "Martha Stewedprune";
print <<"EOT";
=====
This is an example of text taken literally except that variables are expanded where their variable names appear.
foo: $foo
bar: $bar
EOT
#print =====
This is an example of text taken literally except that variables are expanded where their variable names appear.
foo: 123.45
bar: Martha Stewedprune
