This article explains how to set a custom umask in Mac OS X v10.5.3 and later.Every file or folder has permissions associated with it. When you create a file or folder, the umask setting determines these permissions. The permissions on a file can be represented by a number with three digits of 0-7. When you create a file, the umask value is subtracted from a default value (usually 666 for files, 777 for folders) to determine the permissions on the new file or folder. For example, the default umask of 022 results in permissions of 644 on new files and 755 on new folders: groups and other users can read the files and traverse the folders, but only the owner can make changes. For more information on permissions and their numerical representation, see this article.When you create a file, the umask value is subtracted from this maximum permissions value to determine the permissions on the new file or folder. For example, the default umask of 022 results in permissions of 755 on new files or folders: the owner has full access, while the group and others can read and execute, but not write to the file.System administrators may wish to set more or less restrictive umasks for their users. There are several different places in which a umask can be set, each affecting different applications.
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