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Top Forums Shell Programming and Scripting How can find Null value in If condition Post 302127272 by vino on Tuesday 17th of July 2007 04:39:57 AM
Old 07-17-2007
NULL strings would translate to a string of length zero.

You could do this to check for the NULL'ness of a string.

Code:
if [ ! -n "$VARIABLE" ] ; then
  echo "VARIABLE is empty"
fi ;

or

Code:
if [ -z "$VARIABLE" ] ; then
  echo "VARIABLE is empty"
fi ;

See man test to see the description of the flags -n and -z
 

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PPI::Statement::Null(3) 				User Contributed Perl Documentation				   PPI::Statement::Null(3)

NAME
PPI::Statement::Null - A useless null statement SYNOPSIS
my $foo = 1; ; # <-- Null statement my $bar = 1; INHERITANCE
PPI::Statement::Null isa PPI::Statement isa PPI::Node isa PPI::Element DESCRIPTION
"PPI::Statement::Null" is a utility class designed to handle situations where PPI encounters a naked statement separator. Although strictly speaking, the semicolon is a statement separator and not a statement terminator, PPI considers a semicolon to be a statement terminator under most circumstances. In any case, the null statement has no purpose, and can be safely deleted with no ill effect. METHODS
"PPI::Statement::Null" has no additional methods beyond the default ones provided by PPI::Statement, PPI::Node and PPI::Element. SUPPORT
See the support section in the main module. AUTHOR
Adam Kennedy <adamk@cpan.org> COPYRIGHT
Copyright 2001 - 2011 Adam Kennedy. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of the license can be found in the LICENSE file included with this module. perl v5.16.2 2011-02-25 PPI::Statement::Null(3)
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