Checking for null condition in a UNIX variable Post: 302827949

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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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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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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 OSF1

ppmtosixel

ppmtosixel(1)						      General Commands Manual						     ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.	The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
	      pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order	of  magni-
	      tude larger than a compressed file and prints much slower.

       -margin
	      If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
	      fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater	than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

								   26 April 1991						     ppmtosixel(1)

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