Sponsored Content
Top Forums Shell Programming and Scripting Value of variable is NULL, but test doesn't seem to recognize Post 302623635 by intelinside on Saturday 14th of April 2012 07:26:38 AM
Old 04-14-2012
Value of variable is NULL, but test doesn't seem to recognize

Hello, Unix-forums!

My problem:
Code:
read -p "Enter any number, please" number
sleep 1
echo $number | tr -d 0-9
test -z $number && echo "Thank you" || echo "This is not a number"

Test always displays "This is not a number". It doesn't matter if I entered a or 1.

But if I order
Code:
echo $number

before the test command, it displays nothing, so the $number should be NULL, not?

Last edited by intelinside; 04-14-2012 at 08:37 AM..
 

9 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Doesn't recognize the mv command

I'm nearly finished my program i've got everything in place and than when i run it it comes back with the reply mv: command not found. This is the code that seems to be causing the problem. elif then echo "There are more than one '$1' files in the system." echo "Please... (2 Replies)
Discussion started by: zoolz
2 Replies

2. Shell Programming and Scripting

test Null variable

hi forum i beginning with script and i want test un null variable in a schell i just don t know the syntax here is a litle example y=test echo $y unset y echo $y (so here Y = Null) if Y=Null then echo "y is null" exit fi (1 Reply)
Discussion started by: kykyboss
1 Replies

3. HP-UX

HP-UX 11.11: X doesn't recognize mouse and keyboard

hi folks, i've got a blank hp visualize C3000 workstation and installed HP-UX 11.11. When I want to start X, I get the following error message: # X Fatal server error: Couldn't open X pointer device! Is one attached? I've connected an mouse and a keyboard with an usb/ps2 connector.... (5 Replies)
Discussion started by: grisu
5 Replies

4. 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

5. Programming

Kernel module - How to test if file doesn't exist

Hey, I'm currently getting into some kernel module progamming. As a little exercise I want to read the headers out of an ELF file. My code is very simple, here is the important part: struct file *fp; /* ... */ fp = filp_open("some/file/on/my/pc", O_RDONLY, 0); if(fp == NULL) { ... (15 Replies)
Discussion started by: disaster
15 Replies

6. Shell Programming and Scripting

Expect doesn't recognize a password prompt

Hi. Here is beginning of my script #!/usr/local/bin/expect -- set timeout 15 spawn /usr/local/account.sh -n modify expect "Password:" {send "mypassword\r"} But due to some terminal control sequences (or something else, dunno exactly) my password prompt is looking like this: and expect... (3 Replies)
Discussion started by: urello
3 Replies

7. Shell Programming and Scripting

[Solved] If doesn't evaluate the first test

Good afternoon, I am tearing hair out over this. It should be so simple. I have an if statement to evaluate whether or not replication is working. I am testing variables from mysql to see if they are both "Yes". I have put some echo statements in to see how far the code proceeds. It always... (6 Replies)
Discussion started by: jimm
6 Replies

8. Shell Programming and Scripting

How to test that a string doesn't contain specific characters?

Hi ! :) I made this : #!/bin/bash rsa_dir="/etc/openvpn/easy-rsa/" rsa_key_dir="/etc/openvpn/easy-rsa/keys/" ccd_dir="/etc/openvpn/ccd/" regex_special_char='' cd $rsa_dir while read -p "Please can you enter the vpn's username : " username ] || ] || ] || ] do echo "Your entry... (10 Replies)
Discussion started by: Arnaudh78
10 Replies

9. IP Networking

DNS problem : ping doesn't recognize hostname

I have vmware on my windows PC ( hostname : acer ). vmware has RHEL 7 ( hostname : rhel7 ) installed recently. RHEL IP configuration IP : 192.168.5.128 Netmask : 255.255.255.0 ssh to rhel7 works from acer using putty resolve.conf cat /etc/resolv.conf nameserver 192.168.5.1 host... (12 Replies)
Discussion started by: hiten.r.chauhan
12 Replies
xpacmdnew(3)							SAORD Documentation						      xpacmdnew(3)

NAME
XPACmdNew - create a new XPA public access point for commands SYNOPSIS
#include <xpa.h> XPA XPACmdNew(char *class, char *name); DESCRIPTION
Create a new XPA public access point for commands that will share a common identifier class:name. Enter this access point into the XPA name server, so that it can be accessed by external processes. XPACmdNew() returns an XPA struct. It often is more convenient to have one public access point that can manage a number of commands, rather than having individual access points for each command. For example, it is easier to command the ds9 image display using: echo "colormap I8" | xpaset ds9 echo "scale log" | xpaset ds9 echo "file foo.fits" | xpaset ds9 then to use: echo "I8" | xpaset ds9_colormap echo "log" | xpaset ds9_scale echo "foo.fits" | xpaset ds9_file In the first case, the commands remain the same regardless of the target XPA name. In the second case, the command names must change for each instance of ds9. That is, if a second instance of ds9 called DS9 were running, it would be commanded either as: echo "colormap I8" | xpaset DS9 echo "scale log" | xpaset DS9 echo "file foo.fits" | xpaset DS9 or as: echo "I8" | xpaset DS9_colormap echo "log" | xpaset DS9_scale echo "foo.fits" | xpaset DS9_file Thus, in cases where a program is going to manage many commands, it generally is easier to define them as commands associated with the XPACmdNew() routine, rather than as separate access points using XPANew(). When XPACmdNew() is called, only the class:name identifier is specified. Each sub-command is subsequently defined using the XPACmdAdd() routine. SEE ALSO
See xpa(7) for a list of XPA help pages version 2.1.14 June 7, 2012 xpacmdnew(3)
All times are GMT -4. The time now is 03:41 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy