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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..
 

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PAPS(1) 						      General Commands Manual							   PAPS(1)

NAME
paps - UTF-8 to PostScript converter using Pango SYNOPSIS
paps [options] files... DESCRIPTION
paps reads a UTF-8 encoded file and generates a PostScript language rendering of the file. The rendering is done by creating outline curves through the pango ft2 backend. OPTIONS
These programs follow the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is included below. --landscape Landscape output. Default is portrait. --columns=cl Number of columns output. Default is 1. Please notice this option isn't related to the terminal length as in a "80 culums terminal". --font=desc Set the font description. Default is Monospace 12. --rtl Do right to left (RTL) layout. --paper ps Choose paper size. Known paper sizes are legal, letter and A4. Default is A4. Postscript points Each postscript point equals to 1/72 of an inch. 36 points are 1/2 of an inch. --bottom-margin=bm Set bottom margin. Default is 36 postscript points. --top-margin=tm Set top margin. Default is 36 postscript points. --left-margin=lm Set left margin. Default is 36 postscript points. --right-margin=rm Set right margin. Default is 36 postscript points. --gutter-width=gw Set gutter width. Default is 40 postscript points. --help Show summary of options. --header Draw page header for each page. --markup Interpret the text as pango markup. --lpi Set the lines per inch. This determines the line spacing. --cpi Set the characters per inch. This is an alternative method of specifying the font size. --stretch-chars Indicates that characters should be stretched in the y-direction to fill up their vertical space. This is similar to the texttops behaviour. AUTHOR
paps was written by Dov Grobgeld <dov.grobgeld@gmail.com>. This manual page was written by Lior Kaplan <kaplan@debian.org>, for the Debian project (but may be used by others). April 17, 2006 PAPS(1)
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