Error message is stored in $! : Special Variables « Language Basics « Perl

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Perl » Language Basics » Special Variables

Error message is stored in $!


   





#!/usr/bin/perl -w



use strict;



open(FH, '<', 'yourFileName.dat') or die $!;



print "goodopen.dat opened successfully\n";



close FH;

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30.	Code the $_ specifically
31.	Compare value entered with number with underscore
32.	Extracts information from the $] variable.
33.	$! is the error number
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35.	$" is the separator
36.	$# is the default format
37.	$(dollar), is the separator
38.	$MATCH = $&
39.	$SIG{__DIE__}
40.	$SIG{__WARN__} = 'IGNORE';
41.	$SIG{__WARN__} = sub {die "Warning: $_[0]"};
42.	$\ is 'END_OF_OUTPUT'
43.	$^ is the format header
44.	$^O stores the name of the operating system
45.	$^S: is inside eval
46.	$^W: Check the '-w switch'
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48.	$_ for print function
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50.	$~ is the format
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59.	Local builtin var
60.	Locate all numbers less than 6
61.	Manipuate @_ and return @_
62.	Mannually change the $1 variable
63.	Match: $&
64.	Perl 5 Built-In Variables
65.	Perl's modules reside in the directories named in the @INC array, or subdirectories
66.	Perl's special arrays
67.	Perl's special variables
68.	Postmatch $'
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70.	Print all command line argument
71.	Print the default variable's ($_) value
72.	Quick Sum
73.	Read and set environment variables?
74.	Read lines from supplied filenames
75.	Reference element in @_
76.	Resetting array base
77.	Retrieving the Entire Pattern: $&
78.	Saving in the $& special scalar
79.	Set the $/ and chomp
80.	Special Variables
81.	System variables that control how write sends output to a file
82.	Test of open and die with $!.
83.	The $_ Scalar Variable
84.	The @* field
85.	The @ISA Array and Calling Methods
86.	The Argument Vector @ARGV
87.	The Pattern-Matching Operator and $_
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100.	Using @_ directly
101.	Using __LINE__ to output line number
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103.	Using the $. variable.
104.	Using the $;(dollar and semicolon) variable.
105.	Using the @_ to reference the parameter
106.	Using the Default Variable $_
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116.	foreach (@_)
117.	foreach loop and $_
118.	or die $!
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127.	undef $/;

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