Sponsored Content
Top Forums Shell Programming and Scripting Checking for null condition in a UNIX variable Post 302827923 by rafa_fed2 on Monday 1st of July 2013 05:49:42 AM
Old 07-01-2013
Quote:
Originally Posted by RudiC
What shell do you use? Read its man page!

You will find sth like [ ! -s sql_output.txt ] will do what you need.
i am using bash.
-s checks if file is emty or not?
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

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... (14 Replies)
Discussion started by: trynew
14 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. 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

4. Shell Programming and Scripting

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... (4 Replies)
Discussion started by: ganapathi.t
4 Replies

5. Programming

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.... (3 Replies)
Discussion started by: vijaymrt
3 Replies

6. Programming

Checking an array for NULL in C++

Hello All, I have this question that how to check for an array for NULL? For eg. #include<iostream.h> using namespace std; int main() { char arr; if(arr == NULL) { cout<<"NULL"; } } Thanks a lott in advance!!! (3 Replies)
Discussion started by: mind@work
3 Replies

7. Shell Programming and Scripting

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 (6 Replies)
Discussion started by: Ananthdoss
6 Replies

8. Shell Programming and Scripting

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 ... (1 Reply)
Discussion started by: infyanurag
1 Replies

9. Shell Programming and Scripting

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... (3 Replies)
Discussion started by: lovelysethii
3 Replies

10. 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 (3 Replies)
Discussion started by: AraR87
3 Replies
OPEN(1) 							     Linux 1.x								   OPEN(1)

NAME
open - start a program on a new virtual terminal (VT). SYNOPSIS
open [-c vtnumber] [-s] [-u] [-l] [-v] [--] command command_options DESCRIPTION
open will find the first available VT, and run on it the given command with the given command options, standard input, output and error are directed to that terminal. The current search path ($PATH) is used to find the requested command. If no command is specified then the envi- ronment variable $SHELL is used. OPTIONS -c vtnumber Use the given VT number and not the first available. Note you must have write access to the supplied VT for this to work. -s Switch to the new VT when starting the command. The VT of the new command will be made the new current VT. -u Figure out the owner of the current VT, and run login as that user. Suitable to be called by init. Shouldn't be used with -c or -l. -l Make the command a login shell. A - is prepended to the name of the command to be executed. -v Be a bit more verbose. -w wait for command to complete. If -w and -s are used together then open will switch back to the controlling terminal when the command completes. -- end of options to open. NOTE
If open is compiled with a POSIX (Gnu) getopt() and you wish to set options to the command to be run, then you must supply the end of options -- flag before the command. EXAMPLES
open can be used to start a shell on the next free VT, by using the command: open bash To start the shell as a login shell, use: open -l bash To get a long listing you must supply the -- separator: open -- ls -l SEE ALSO
login(1), doshell(8), switchto(1). AUTHOR
Jon Tombs <jon@gtex02.us.es or jon@robots.ox.ac.uk> -w idea from "sam". 19 Jul 1996 V1.4 OPEN(1)
All times are GMT -4. The time now is 02:28 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy