Checking for null condition in a UNIX variable Post: 302827925

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Condition checking

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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Checking for null value

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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Checking the variable in UNIX

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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Condition checking in UNIX

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 LINUX

shtool-echo

SHTOOL-ECHO.TMP(1)					      GNU Portable Shell Tool						SHTOOL-ECHO.TMP(1)

NAME

       shtool-echo - GNU shtool echo(1) extensional command

SYNOPSIS

       shtool echo [-n|--newline] [-e|--expand] string

DESCRIPTION

       shtool echo is an echo(1) style command which prints string to stdout and optionally provides special expansion constructs (terminal bold
       mode, environment details, date, etc) and newline control. The trick of this command is that it provides a portable -n option and hides the
       gory details needed to find out the environment details under option -e.

OPTIONS

       The following command line options are available.

       -n, --newline
	   By default, output is written to stdout followed by a "newline" (ASCII character 0x0a). If option -n is used, this newline character is
	   omitted.

       -e, --expand
	   If option -e is used, string can contain special "%x" constructs which are expanded before the output is written. Currently the
	   following constructs are recognized:

	   %B  switch terminal mode to bold display mode.

	   %b  switch terminal mode back to normal display mode.

	   %u  the current user name.

	   %U  the current user id (numerical).

	   %g  the current group name.

	   %G  the current group id (numerical).

	   %h  the current hostname (without any domain extension).

	   %d  the current domain name.

	   %D  the current day of the month.

	   %M  the current month (numerical).

	   %m  the current month name.

	   %Y  the current year.

EXAMPLE

	#   shell script
	shtool echo -n -e "Enter your name [%B%u%b]: "; read name
	shtool echo -e "Your Email address might be %u@%h%d"
	shtool echo -e "The current date is %D-%m-%Y"

HISTORY

       The GNU shtool echo command was originally written by Ralf S.  Engelschall <rse@engelschall.com> in 1998 for Website META Language (WML)
       under the name buildinfo. It was later taken over into GNU shtool.

SEE ALSO

       shtool(1), echo(1).

18-Jul-2008							   shtool 2.0.8 						SHTOOL-ECHO.TMP(1)

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