If an application has permissions set to Rw-r—r— but does not run, why is that?

When an application has permissions set to Rw-r—r—, this indicates the following:

• The owner of the file has read and write permissions (denoted by the 'Rw-').

• The members of the group associated with the file have read permissions only (denoted by 'r--').

• Others (users not in the file's group) also have read permissions only (denoted by 'r--').

For an executable file to run, it needs to have the execute permission set for the relevant users. In this case, since the permission string is missing the execute permission ('x'), users—including the owner, group members, and others—cannot execute the application.

Therefore, the lack of execute permission is directly why the application does not run. Without this permission, any attempt to execute the file will result in an error indicating that the file cannot be executed, regardless of the read or write permissions present.