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Need to understand shell script

 
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# 1  
Old 10-25-2013
Need to understand shell script
Hello,

Can someone please help me understand the shell script below for installing Jboss EAP 6? It is from jboss-as-standalone.sh, what does the highlighted code mean?

Code:
# Load Java configuration.
[ -r /etc/java/java.conf ] && . /etc/java/java.conf
export JAVA_HOME

Thanks!
# 2  
Old 10-25-2013
Have look at the manual page for test

Does that make it any clearer? It's better for you to learn it than for me to just tell you an answer, but I will happily do so if it still doesn't make sense.




Robin
Liverpool/Blackburn
UK
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# 3  
Old 10-25-2013
Code:
# Load Java configuration.

[ -r /etc/java/java.conf ] \               # what is in between []  is a condition expression, -r expects 
a file after which is the case here and is true if it exists and readable by the current process
&&\      # if success execute what follows:
 . /etc/java/java.conf   
export JAVA_HOME

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# 4  
Old 10-25-2013
Thanks! Found

Code:
# man test
-r FILE
              FILE exists and read permission is granted

I also learned that && means more than the traditional AND. But what does the dot mean in the following code. I assume it does NOT mean the current directory.

Code:
. /etc/java/java.conf

# 5  
Old 10-25-2013
. means 'run this program inside your own shell'. This allows it to set variables inside your shell, which wouldn't be possible if you ran a script with ./scriptname -- when you create a new process its variables are separate.
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