The effective permissions of a file created with the permissions777can be calculated considering thecreate maskandforce create mode.

create mask = 711implies that the permission bits are ANDed with 0711, i.e., only the owner can read, write, and execute.

force create mode = 750implies that certain permission bits are always set, specifically 0750, i.e., read, write, and execute for the owner, and read and execute for the group.

Thecreate maskreduces the permissions to 0711, and thenforce create modeadds the 0750 mask to the result.

Original permission:777AND withcreate mask (711):711OR withforce create mode (750):751

Thus, the effective permission is751.

References:

Samba smb.conf man page - create mask