Sponsored Content
Top Forums Shell Programming and Scripting If condition to check null variable Post 302831431 by wisecracker on Thursday 11th of July 2013 03:20:35 AM
Old 07-11-2013
Be aware:-
Code:
#!/bin/bash
nulltest()
{
if [ ${#var} -eq 0 ]
then
	echo "NULL, empty string..."
else
	echo "Not an empty string..."
fi
}
var=""
nulltest
var=NULL
nulltest

Gives results:-
Code:
Last login: Thu Jul 11 07:58:36 on ttys000
AMIGA:barrywalker~> ./null.sh
NULL, empty string...
Not an empty string...
AMIGA:barrywalker~>


Last edited by wisecracker; 07-11-2013 at 11:01 AM.. Reason: Missed out the braces...
 

10 More Discussions You Might Find Interesting

1. 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 (2 Replies)
Discussion started by: esham
2 Replies

2. Shell Programming and Scripting

How can find Null value in If condition

Hi, i wrote If Conditions in my script, it's returns null and some values. but i am unable to find when Null value getting. bec we need modification according null vales. pls help me on this. (2 Replies)
Discussion started by: koti_rama
2 Replies

3. Shell Programming and Scripting

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. (2 Replies)
Discussion started by: sachin.gangadha
2 Replies

4. UNIX for Dummies Questions & Answers

How to compare null and space using single if condition

Hi I have a input file with many fields and each filed will be with in double quotes(""). i want to check fields contains balnk,null or space using condition using if. when i write code as below for if condition its not working a=`awk -F ',' '{gsub("\"", "", $1);'NF==0';printf $1}'... (3 Replies)
Discussion started by: jayakumarrt
3 Replies

5. Shell Programming and Scripting

csh if loop variable condition check peroblem

Hi, I have variables like var1 var2 var3 var4 in if loop i am trying to check the condition if(variable == "var") then echo $variable endif (0 Replies)
Discussion started by: vasanth.vadalur
0 Replies

6. Shell Programming and Scripting

check for null

hi, i have 3 lines of output , if second line exists then only condition within the if loop has to exeute other wise it has exit from loop. i had tried like this but not getting please help me ... Code: if ; then echo "success" else echo "" Use code tags please,... (8 Replies)
Discussion started by: sreelu
8 Replies

7. Shell Programming and Scripting

Check for null

Hi Champs!!! im a newbie in unix, need ur expert help for my problem... I need to search if there are any "NULL" entries in the string String without Null Str1: 203652|1000003653|tellt|RUPV|4649|1|07/28/2011 01:56:12 String with Null (RUPV is removed) Str2:... (5 Replies)
Discussion started by: guruprasad7
5 Replies

8. Shell Programming and Scripting

HELP with AWK one-liner. Need to employ an If condition inside AWK to check for array variable ?

Hello experts, I'm stuck with this script for three days now. Here's what i need. I need to split a large delimited (,) file into 2 files based on the value present in the last field. Samp: Something.csv bca,adc,asdf,123,12C bca,adc,asdf,123,13C def,adc,asdf,123,12A I need this split... (6 Replies)
Discussion started by: shell_boy23
6 Replies

9. Shell Programming and Scripting

Check null value in xml

Hi, I have a log file which is having some xml tags. I need to check the value for a particular xml field is null or not and if it is null i have to add current time as the value for that xml field. I tried below code to check whether the word count is 0. But even if the xml field is null it... (16 Replies)
Discussion started by: Neethu
16 Replies

10. Shell Programming and Scripting

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 ... (5 Replies)
Discussion started by: rafa_fed2
5 Replies
bup-margin(1)						      General Commands Manual						     bup-margin(1)

NAME
bup-margin - figure out your deduplication safety margin SYNOPSIS
bup margin [options...] DESCRIPTION
bup margin iterates through all objects in your bup repository, calculating the largest number of prefix bits shared between any two entries. This number, n, identifies the longest subset of SHA-1 you could use and still encounter a collision between your object ids. For example, one system that was tested had a collection of 11 million objects (70 GB), and bup margin returned 45. That means a 46-bit hash would be sufficient to avoid all collisions among that set of objects; each object in that repository could be uniquely identified by its first 46 bits. The number of bits needed seems to increase by about 1 or 2 for every doubling of the number of objects. Since SHA-1 hashes have 160 bits, that leaves 115 bits of margin. Of course, because SHA-1 hashes are essentially random, it's theoretically possible to use many more bits with far fewer objects. If you're paranoid about the possibility of SHA-1 collisions, you can monitor your repository by running bup margin occasionally to see if you're getting dangerously close to 160 bits. OPTIONS
--predict Guess the offset into each index file where a particular object will appear, and report the maximum deviation of the correct answer from the guess. This is potentially useful for tuning an interpolation search algorithm. --ignore-midx don't use .midx files, use only .idx files. This is only really useful when used with --predict. EXAMPLE
$ bup margin Reading indexes: 100.00% (1612581/1612581), done. 40 40 matching prefix bits 1.94 bits per doubling 120 bits (61.86 doublings) remaining 4.19338e+18 times larger is possible Everyone on earth could have 625878182 data sets like yours, all in one repository, and we would expect 1 object collision. $ bup margin --predict PackIdxList: using 1 index. Reading indexes: 100.00% (1612581/1612581), done. 915 of 1612581 (0.057%) SEE ALSO
bup-midx(1), bup-save(1) BUP
Part of the bup(1) suite. AUTHORS
Avery Pennarun <apenwarr@gmail.com>. Bup unknown- bup-margin(1)
All times are GMT -4. The time now is 07:13 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy