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Full Discussion: A nice way to check a string
Top Forums Shell Programming and Scripting A nice way to check a string Post 302592565 by methyl on Tuesday 24th of January 2012 09:23:36 AM
Old 01-24-2012
Both "test -z" and "test -n" need the string variable in double quotes:

Code:
These two tests are identical:

if [  -z "${LDN_MEDIA_SERVER_HOST}" ] ; then

if [  ! -n "${LDN_MEDIA_SERVER_HOST}" ] ; then

 

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learn(1)						      General Commands Manual							  learn(1)

NAME
learn - Provides computer-aided instruction for the C shell SYNOPSIS
learn [-directory] [subject] [lesson] The learn command provides computer-aided instruction courses and practice in the use of Tru64 UNIX. OPTIONS
Allows you to exercise a script in a nonstandard place. DESCRIPTION
To get started, enter learn; if this is the first time that you are invoking the learn command, you are guided through a series of ques- tions to determine what type of instruction you want to receive. If you have used learn before and left your last session without completing a subject, the program uses information in $HOME/.learnrc to start you up in the same place you left off. To bypass questions, enter a subject or lesson. In order to enter a lesson, you must know the lesson number that you received in a previ- ous learn command session. If you do not know the lesson number, enter the lesson number as a subject. The learn command searches for the first lesson containing the subject you specified. If the lesson is a - (dash), learn prompts for each lesson; this is useful for debug- ging. You can specify the following subjects: files editor vi morefiles macros eqn C SUBCOMMANDS
There are a few special commands. The bye command terminates a learn session, and the where command tells you of your progress (where m tells you more.) The again command redisplays the text of the lesson and again lesson lets you review lesson. The hint command prints the last part of the lesson script used to evaluate a response, while hint m prints the entire lesson script. This is useful for debugging lessons and might possibly give you an idea about what is expected. EXAMPLES
To take the online lesson about files, enter: learn files You are then prompted for further input. FILES
Playpen directories. Start-up information. SEE ALSO
Commands: csh(1), ex(1) learn(1)
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