I do not know why I had not already seen a report of this issue on the forum, so I mention it for the benefit of others. As I simply solved it, perhaps others deemed it to be so simple that they did not need to ask for help, or maybe many people have not yet installed Version 11.0.
Depending on which optional packages are chosen to be installed, the error messages can be different, for example
…/install_mpich: line 109: …/linux86/11.0/bin/localrc: No such file or directory
The subdirectory /.parts referred to in the script install does not exist
so replacing /.parts with the empty string can avoid one error message.
The for loop starting with
for i in $PART ; do
can be manually replaced with for example
cp -R linux86-64 $INSTALL_DIR
for a minimal installation.