On Wed, 17 Sep 2008, Tim Wilson wrote: > I've never been able to wrap my head around umask either. My understanding (which seems to be working for me)... umask is used to determine default file permissions. File permissions can be written in terms of letters r, w, x (for permission to read, write or execute the file, respectively), but the numbers 4, 2, 1 can be used instead of r, w, x, respectively and those numbers can be summed. So the number 6 means read and write, 5 means read and execute, etc. The other aspect of permissions is *who* has them. We use order to designate this: first is owner, second is group and third is "other" (which means everyone, really). So the permissions 750 means that owner can read, write or execute, group members can read and execute, but others can not do anything. The most common permissions seem to be 755 (for directories or executable files) and 644 for non executable files. Now to umask. The umask is a string of three digits that are subtracted away from 777 (directories and executables) or 666 (other files) to give the default permissions for a newly created file. So the permissions for a new directory or file could be written like so: 777-umask 666-umask If the umask is 022, and it often is, this would yield the usual 755 and 644 permissions. I think a negative number is treated as zero so that a umask of 027 yields 640 for new regular files. I'm sure there is a lot more to know, but that is my simple-minded approach that works most of the time. Mike