Problem
On linux distributions like Ubuntu or CentOS, when launching Firefox or some other programs by command line the error message "Couldn’t load XPCOM" is returned.
Issue
The error is caused by the lack of the path "/usr/lib" in the environment variable LD_LIBRARY_PATH
Solution
Add the /usr/lib path to the environment variable in this way:
export LD_LIBRARY_PATH=/usr/lib:$LD_LIBRARY_PATH;