How to get path and check in if statement

Shell Programming and Scripting
1

Hi,

I was wondering if it possible to get the path of a variable and compare that to something. Basically I want to write a script that checks if my $JAVA_HOME is correct and if not then it sets it. So far I have...

if [[$JAVA_HOME != '/pathhere']]
then
export JAVA_HOME='/pathhere'
echo JAVA_HOME='/pathhere'
fi

Problem is that the script can't seem to understand that I want to compare the path $JAVA_HOME and not what's in there. Anyone know how to just extract the path from that already set variable? Thanks!

2

Your question doesn't make sense. Your code already compares the value of $JAVA_HOME to the string /pathhere; how this is or isn't "what's in there" is not quite clear.

Depending on your shell, you might need to add spaces inside the [[ ... ]] delimiters in order for the syntax to validate. Is that your problem?

Speculatively, if you want to check if a colon-delimited path contains /pathhere anywhere in it, and if not, add it, try this:

case :$JAVA_HOME: in *:/pathhere:*) ;; *) JAVA_HOME=/pathhere:"$JAVA_HOME";; esac
3

well reason why im confused is that when i tried to run the script it errors in the if condition. it gives me this...

/System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Home: No such file or directory

where that path is the $JAVA_HOME. It shouldn't matter if that file or directory exist right, I just want to check that value which is the problem

4

Try adding those spaces, and also quote the variable. (case is less picky about quoting and works even in good ole /bin/sh which doesn't have this fancy [[ ... ]] stuff.)

case $JAVA_HOME in /pathhere) ;; JAVA_HOME=/pathhere;; esac
5

ok cool I tried the space thing and it worked! Thanks!

How exactly does case work? Is it like if the first element is a part of the second element then do then else this? Sorta like that?

6

No, it's basically a generalization of if then else if then else if then else, but all branches examine the same variable. In many programming languages, this is a "switch" statement (think railroad switch). Read the documentation for your shell.

7 
test -e $JAVA_HOME

or use if statement.