Sponsored Content
Top Forums Shell Programming and Scripting Value of variable is NULL, but test doesn't seem to recognize Post 302623637 by radoulov on Saturday 14th of April 2012 07:36:17 AM
Old 04-14-2012
Try:

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

Actually you could avoid calling external commands in this case:

Code:
read -p 'Enter any number, please: ' number
sleep 1
test -z "${number//[0-9]}" && 
  echo "Thank you" || 
    echo "This is not a number"

P.S. The code above uses non standard shell features, but that shouldn't be
a problem, considering that the original post uses non standard features too Smilie
This User Gave Thanks to radoulov For This Post:
 

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
SLEEP(3)								 1								  SLEEP(3)

sleep - Delay execution

SYNOPSIS
int sleep (int $seconds) DESCRIPTION
Delays the program execution for the given number of $seconds. PARAMETERS
o $seconds - Halt time in seconds. RETURN VALUES
Returns zero on success, or FALSE on error. If the call was interrupted by a signal, sleep(3) returns a non-zero value. On Windows, this value will always be 192 (the value of the WAIT_IO_COMPLETION constant within the Windows API). On other platforms, the return value will be the number of seconds left to sleep. ERRORS
/EXCEPTIONS If the specified number of $seconds is negative, this function will generate a E_WARNING. CHANGELOG
+--------+---------------------------------------------------+ |Version | | | | | | | Description | | | | +--------+---------------------------------------------------+ | 5.3.4 | | | | | | | Before PHP 5.3.4, on Windows, sleep(3) always | | | returns NULL when sleep has occurred, regardless | | | of whether the sleep was interrupted or not. | | | | +--------+---------------------------------------------------+ EXAMPLES
Example #1 sleep(3) example <?php // current time echo date('h:i:s') . " "; // sleep for 10 seconds sleep(10); // wake up ! echo date('h:i:s') . " "; ?> This example will output (after 10 seconds) 05:31:23 05:31:33 SEE ALSO
usleep(3), time_nanosleep(3), time_sleep_until(3), set_time_limit(3). PHP Documentation Group SLEEP(3)
All times are GMT -4. The time now is 04:03 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy