Finding Files
6.2.2 Copying Existing Permissions
You can base part of a file's permissions on part of its existing
permissions. To do this, instead of using `r', `w', or
`x' after the operator, you use the letter `u', `g', or
`o'. For example, the mode
adds the permissions for users who are in a file's group to the
permissions that other users have for the file. Thus, if the file
started out as mode 664 (`rw-rw-r--'), the above mode would change
it to mode 666 (`rw-rw-rw-'). If the file had started out as mode
741 (`rwxr----x'), the above mode would change it to mode 745
(`rwxr--r-x'). The `-' and `=' operations work
analogously.
