[rfc][icedtea-web] get the custom jre in shell-launchers too

[Omair Majid]

On 03/20/2013 03:47 PM, Adam Domurad wrote:
> On 03/20/2013 06:54 AM, Jiri Vanek wrote:
>> +CUSTOM_JRE_REGEX="^deployment.jre.dir *= *"
>> +CUSTOM_JRE=`grep "$CUSTOM_JRE_REGEX" ~/.icedtea/deployment.properties
>> 2>/dev/null |  sed "s/$CUSTOM_JRE_REGEX//g"`
>> +if [ "x$CUSTOM_JRE" = "x" ] ; then
> 
> Please just use [ "$CUSTOM_JRE" = "" ] instead of this mysterious thing.

I don't know if "mysterious" is the right word for this. This is a
fairly common idiom. Older shells, using simple string substitution,
could interpret

if [ "$CUSTOM_JRE" = "foo" ] ; then

as

if test = foo ; then

which is a syntax error. The use of "x" to avoid this is a common idiom
that you can find in lots of places (like in our acinclude.m4 files).

The "x" also avoids nasty surprises if $CUSTOM_JRE evaluates to "-z" or
something.

However, if we are just checking if a variable is empty, perhaps -z is
more appropriate:

if [ -z "$CUSTOM_JRE" ] ; then
 ...

Cheers,
Omair

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