A quick explanation of umask (php, but it still applies)

Jill Ramonsky Apr 2 2003
Subject: RE: PHP-WIN how to use umask() ???

The PHP manual (unfortunately) assumes some Unix knowledge here.

The paramter to umask is a bitfield, passed as an integer. Within this bitfield:

• bit 0 set implies that anyone in the world can execute the file
• bit 1 set implies that anyone in the world can write to the file
• bit 2 set implies that anyone in the world can read the file
• bit 3 set implies that anyone in the file's group (a Unix concept) can execute the file
• bit 4 set implies that anyone in the file's group (a Unix concept) can write to the file
• bit 5 set implies that anyone in the file's group (a Unix concept) can read the file
• bit 6 set implies that the owner of the file can execute the file
• bit 7 set implies that the owner of the file can write to the file
• bit 8 set implies that the owner of the file can read the file

When accessing a file, the lower 9 bits of the permissions of the file (as stored on the server) are logically ANDed with the complement of the current "umask" - which you can set with the umask() function - and the resulting bitfield is inspected to see whether or not to grant permission for the specified action.

Jill