PERL: how to tell if variable is NULL Post: 34864

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1. Shell Programming and Scripting

How to filter a null variable.

I have the necessity to use this command: cat file1 | grep $A | grep $B where sometime A and, or, B are not set. For example: I set A=@ never defined or set B The above command send a cat error. Any idea? Thanks. Giovanni

2. Shell Programming and Scripting

check for NULL variable

Hello I want to check for NULL variable.. but this is not working..please help thanks in advance esham

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test Null variable

hi forum i beginning with script and i want test un null variable in a schell i just don t know the syntax here is a litle example y=test echo $y unset y echo $y (so here Y = Null) if Y=Null then echo "y is null" exit fi

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not null cheking of an argument in perl

Hi, I have to check whether an argument say $ARGV is not null in an if operator. Please let me know the operator. It would be great if you write a psuedo code. Thanks in advance Ammu

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how to check null variable

korn shell If then update_smartcare_user_password "$u_id" else echo "Not a database user" fi i get this error Syntax error at line *** : `then' is not expected. what should i do. I want to check whether $a is null or not.

6. Shell Programming and Scripting

Question on NULL and zero value of variable

Hi all, I have a stupid question on NULL and zero(0). In a script I've been working with, one of the lines is: if && then The problem I seem to have is when $Current_csm2 is null, this if block is not triggered, and I don't get why because I was under the impression that NULL!=0 Can...

7. Shell Programming and Scripting

Value of variable is NULL, but test doesn't seem to recognize

Hello, Unix-forums! My problem: read -p "Enter any number, please" number sleep 1 echo $number | tr -d 0-9 test -z $number && echo "Thank you" || echo "This is not a number"Test always displays "This is not a number". It doesn't matter if I entered a or 1. But if I order echo...

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Checking for null condition in a UNIX variable

i have this code for i in `cat sql_output.txt` do -- some script commands done sql_output.txt has 1 column with employee_ids If the sql_output.txt is null then the do loop should not execute. How can i implement this. for i in `cat sql_output.txt` If i is null or empty then ...

9. Shell Programming and Scripting

If condition to check null variable

Guys, Please help me on the below sample.cfg var=NULL sample.sh #!/bin/sh . /sample.cfg if ;then 1 st command here else 2 nd command here fi

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If grep value is null then assign 0 to variable

LEARN ABOUT OSX

dbix::class::startupcheck

DBIx::Class::StartupCheck(3)				User Contributed Perl Documentation			      DBIx::Class::StartupCheck(3)

NAME

       DBIx::Class::StartupCheck - Run environment checks on startup

SYNOPSIS

	 use DBIx::Class::StartupCheck;

DESCRIPTION

       This module used to check for, and if necessary issue a warning for, a particular bug found on Red Hat and Fedora systems using their
       system perl build. As of September 2008 there are fixed versions of perl for all current Red Hat and Fedora distributions, but the old
       check still triggers, incorrectly flagging those versions of perl to be buggy. A more comprehensive check has been moved into the test
       suite in "t/99rh_perl_perf_bug.t" and further information about the bug has been put in DBIx::Class::Manual::Troubleshooting.

       Other checks may be added from time to time.

       Any checks herein can be disabled by setting an appropriate environment variable. If your system suffers from a particular bug, you will
       get a warning message on startup sent to STDERR, explaining what to do about it and how to suppress the message. If you don't see any
       messages, you have nothing to worry about.

CONTRIBUTORS

       Nigel Metheringham

       Brandon Black

       Matt S. Trout

AUTHOR

       Jon Schutz

LICENSE

       You may distribute this code under the same terms as Perl itself.

perl v5.16.2							    2011-05-23					      DBIx::Class::StartupCheck(3)

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to filter a null variable.

Discussion started by: gio123bg

2. Shell Programming and Scripting

check for NULL variable

Discussion started by: esham

3. Shell Programming and Scripting

test Null variable

Discussion started by: kykyboss

4. Shell Programming and Scripting

not null cheking of an argument in perl

Discussion started by: ammu