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problem with spaces and argument parsing


 
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Top Forums Shell Programming and Scripting problem with spaces and argument parsing
# 8  
Old 12-19-2007
I posted the last reply too soon.

If I go back to my original posting, and use this as an sh file:
Code:
#!/bin/sh
echo java  -XX:OnError=\"gdb\ -\ %p\"  HelloWorld
java  -XX:OnError=\"gdb\ -\ %p\"  HelloWorld

then everything works: the echo prints correctly, and the java command fully executes.

Great!

But what I really want in my script is for options like the gdb thing to be env vars that can be reused with multiple java invocations. The simplest version of what I really want my build script to look like is
Code:
#!/bin/sh
option=-XX:OnError=\"gdb - %p\"
echo java  $option  HelloWorld
java  $option  HelloWorld

This gives the output
t.sh: line 2: -: command not found
java HelloWorld
Welcome, master
Its clearly not fully correct because it is not using option.

If I change option's line to use escaped spaces
Code:
option=-XX:OnError=\"gdb\ -\ %p\"

the output is
java -XX:OnError="gdb - %p" HelloWorld
Unrecognized option: -
Could not create the Java virtual machine.
which is again problematic.

This, fortunately, is readily corrected by using quotes around option:
Code:
#!/bin/sh
option=-XX:OnError=\"gdb\ -\ %p\"
echo java  "$option"  HelloWorld
java  "$option"  HelloWorld

which actually fully works.

Unfortunately, what I really want is a more complicated script that would look like this
Code:
#!/bin/sh
errorHandling=-XX:OnError=\"gdb\ -\ %p\"
gcType="-XX:+UseParallelGC  -XX:+UseParallelOldGC"
standardJavaOptions="$errorHandling  $gcType"
echo java  $standardJavaOptions  HelloWorld
java  $standardJavaOptions  HelloWorld

Here, I want to build up top level env vars from smaller env vars. Unfortunately, the above script fails again with the usual error ("Unrecognized option: -"). It seems as if every $ substitution causes quoting space nightmares to reappear. This makes it difficult or impossible to sanely build up top level env vars from smaller env vars?

The above results were obtained on both cygwin and linux.
# 9  
Old 12-19-2007
Quote:
Originally Posted by fabulous2
This makes it difficult or impossible to sanely build up top level env vars from smaller env vars?
Alas yes, an option is to write a small utility shell script which will re-escape it's input...

Also you may want to try using "make" rather than shell to do this and see if it's substitution rules work better.

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