![]() For directories, the execute options X and X define permission to view the directory's contents. The letters r, w, x, X, s and t select file mode bits for the affected users: read ( r), write ( w), execute ( x), execute only if the file is a directory or already has execute permission for some user ( X), set user or group ID on execution ( s), restricted deletion flag or sticky bit ( t). ![]() The operator + causes the selected file mode bits to be added to the existing file mode bits of each file - causes them to be removed and = causes them to be added and causes unmentioned bits to be removed except that a directory's unmentioned set user and group ID bits are not affected. If none of these are given, the effect is as if a were given, but bits that are set in the umask are not affected. Multiple symbolic modes can be given, separated by commas.Ī combination of the letters u, g, o, and a controls which users' access to the file will be changed: the user who owns it ( u), other users in the file's group ( g), other users not in the file's group ( o), or all users ( a). Where perms is either zero or more letters from the set r, w, x, X, s and t, or a single letter from the set u, g, and o. Set permissions to match those of file RFILE, ignoring any specified MODE.Ĭhange files and directories recursively.Ĭhmod changes the file mode of each specified FILE according to MODE, which can be either a symbolic representation of changes to make, or an octal number representing the bit pattern for the new mode bits. Verbose mode output a diagnostic message for every file processed.ĭo not treat ' /' (the root directory) in any special way, which is the default setting. Like -verbose, but gives verbose output only when a change is actually made. So 7 is the combination of permissions 4+ 2+ 1 (read, write, and execute), 5 is 4+ 0+ 1 (read, no write, and execute), and 4 is 4+ 0+ 0 (read, no write, and no execute). Each digit is a combination of the numbers 4, 2, 1, and 0: Here the digits 7, 5, and 4 each individually represent the permissions for the user, group, and others, in that order. Here is the equivalent command using octal permissions notation: chmod 754 myfile The commas separate the different classes of permissions, and there are no spaces between them. The equals sign (" =") means "set the permissions exactly like this," and the letters " r", " w", and " x" stand for "read", "write", and "execute", respectively. The letters u, g, and o stand for " user", " group", and " other". This example uses symbolic permissions notation. This command does the trick: chmod u=rwx,g=rx,o=r myfile members of your group can read and e xecute it and.the user can read, write, and e xecute it.Let's say you are the owner of a file named myfile, and you want to set its permissions so that: There are two ways to represent these permissions: with symbols ( alphanumeric characters), or with octal numbers (the digits 0 through 7). Permissions defines the permissions for the owner of the file (the "user"), members of the group who owns the file (the "group"), and anyone else ("others"). If no options are specified, chmod modifies the permissions of the file specified by file name to the permissions specified by permissions. ![]() In general, chmod commands take the form: chmod options permissions file name It contains a comprehensive description of how to define and specify file permissions. These flags are called file permissions or modes, as in "mode of access." The command name chmod stands for "change mode." It restricts the way a file can be accessed.įor more information about file modes, see: What are file permissions, and how do they work? in our documentation of the umask command. On Unix-like operating systems, a set of flags associated with each file determines who can access that file, and how they can access it.
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