While trying to create rsa keypairs for a project inside the project dir I was experimenting with ssh-keygen's -f option.
When I test it in a freshly created directory everything works as expected, but when I try to use the exact same syntax on another equally permissioned directory ssh-keygen just keeps telling me No such file or directory.
In a way it is right saying so, because it is supposed to create these files. (The directory in which it shall work exists.)
The syntax I use for key creation is:
ssh-keygen -q -t rsa -f /abspath/id_rsa -N ""