Checking for null condition in a UNIX variable Post: 302827935

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Dear all That's another problem from me, i wanna do a lot of if statement checking for correct input by user, will be prompt input again if the input not meet the requirement defined by If or while statement... like this one .... while I know it's less effiency write the program...

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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.

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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}'...

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Dear All, I'm glad that I've also joined in this forum. Good work fellas... :b: Keep going...! :) I am having a .csv file where I am reading the values with comma(,) as delimiter. After reading each and every values, I would like to check whether it is empty (say null or blank spaces). How...

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C++ segmentation fault while checking for null pointer

void disptree(node *ptr) { if ((ptr->left) !=NULL) disptree(ptr->left); cout<<"Position:"<<ptr->pos<<" Data:"<<ptr->data<<endl; if ((ptr->right)!=NULL; disptree(ptr->right); } i'm getting a segmentation fault at the red line. i cannot understand what's the problem....

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NULL checking

Hi I need to check the output of a string to null. For eg the output I get for $KIT is empty. So want to echo something when the output is empty. How can I do that? Thanks in advance

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Hi, I have a file abc.txt as ABC,TYU,1.2566 AHG,GJJ,1.898 hgh,FGA,1.854 My program is reading each line and storing the values variables base_cy, quo_cy, ra_amt Need to validate each of them as in: base_cy and quo_cy should be a 3 character alphabet among A-Z, if it is lower case ...

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i have a script where i have to find the age of a file, if then echo "dnb file is present for the monthly load" >> $RUNLOG dnb="1" else echo "dnb file has not arrived yet" > $ERRLOG dnb="0" fi i know the file is available so...

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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

LEARN ABOUT REDHAT

ppmtopgm

ppmtopgm(1)						      General Commands Manual						       ppmtopgm(1)

NAME

       ppmtopgm - convert a portable pixmap into a portable graymap

SYNOPSIS

       ppmtopgm [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as  input.  Produces a portable graymap as output.  The output is a "black and white" rendering of the original
       image, as in a black and white photograph.  The quantization formula used is .299 r + .587 g + .114 b.

       Note that although there is a pgmtoppm program, it is not necessary for simple conversions from pgm to ppm , because any  ppm  program  can
       read  pgm  (and	pbm  ) files automatically.  pgmtoppm is for colorizing a pgm file.  Also, see ppmtorgb3 for a different way of converting
       color to gray.  And ppmdist generates a grayscale image from a color image, but in a way that makes it easy to differentiate  the  original
       colors, not necessarily a way that looks like a black and white photograph.

QUOTE

       Cold-hearted orb that rules the night
       Removes the colors from our sight
       Red is gray, and yellow white
       But we decide which is right
       And which is a quantization error.

SEE ALSO

       pgmtoppm(1),ppmtorgb3(1),rgb3toppm(1),ppmdist(1),ppm(5),pgm(5)

AUTHOR

       Copyright (C) 1989 by Jef Poskanzer.

								   10 April 2000						       ppmtopgm(1)

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