Normally vm options stored in idea.vmoptions and idea64.vmoptions contain no spaces. But whenever you need to set an option which contains one, the idea.sh will fail.
A common use-case for a vm option containing a space is the following line:
-Duser.name=Tom\ Nussbaumer
This will override the user name used in all templates with the given one. To get IDEA working with such a setting you have to edit file idea.sh.
At the very end of the script there is the following block:
LD_LIBRARY_PATH="$IDE_BIN_HOME:$LD_LIBRARY_PATH" "$JDK/bin/java" \
....
$VM_OPTIONS "-Djb.vmOptionsFile=$VM_OPTIONS_FILES_USED" \
....Prefix this block with eval and quote the $VM_OPTIONS variable like this:
eval LD_LIBRARY_PATH="$IDE_BIN_HOME:$LD_LIBRARY_PATH" "$JDK/bin/java" \
....
"$VM_OPTIONS" "-Djb.vmOptionsFile=$VM_OPTIONS_FILES_USED" \
....Done.
BTW, you don't have to modify the global vmoptions files. You can to it in IDEAs local configuration directory. For IDEA 14 community edition this directory is located at $HOME/.IdeaIC14/config.