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chmod(1) [bsd man page]

CHMOD(1)						      General Commands Manual							  CHMOD(1)

NAME
chmod - change mode SYNOPSIS
chmod [ -Rf ] mode file ... DESCRIPTION
The mode of each named file is changed according to mode, which may be absolute or symbolic. An absolute mode is an octal number con- structed from the OR of the following modes: 4000 set user ID on execution 2000 set group ID on execution 1000 sticky bit, see chmod(2) 0400 read by owner 0200 write by owner 0100 execute (search in directory) by owner 0070 read, write, execute (search) by group 0007 read, write, execute (search) by others A symbolic mode has the form: [who] op permission [op permission] ... The who part is a combination of the letters u (for user's permissions), g (group) and o (other). The letter a stands for all, or ugo. If who is omitted, the default is a but the setting of the file creation mask (see umask(2)) is taken into account. Op can be + to add permission to the file's mode, - to take away permission and = to assign permission absolutely (all other bits will be reset). Permission is any combination of the letters r (read), w (write), x (execute), X (set execute only if file is a directory or some other execute bit is set), s (set owner or group id) and t (save text - sticky). Letters u, g, or o indicate that permission is to be taken from the current mode. Omitting permission is only useful with = to take away all permissions. When the -R option is given, chmod recursively descends its directory arguments setting the mode for each file as described above. When symbolic links are encountered, their mode is not changed and they are not traversed. If the -f option is given, chmod will not complain if it fails to change the mode on a file. EXAMPLES
The first example denies write permission to others, the second makes a file executable by all if it is executable by anyone: chmod o-w file chmod +X file Multiple symbolic modes separated by commas may be given. Operations are performed in the order specified. The letter s is only useful with u or g. Only the owner of a file (or the super-user) may change its mode. SEE ALSO
ls(1), chmod(2), stat(2), umask(2), chown(8) 7th Edition May 22, 1986 CHMOD(1)

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CHMOD(2)							System Calls Manual							  CHMOD(2)

NAME
chmod - change mode of file SYNOPSIS
chmod(path, mode) char *path; int mode; fchmod(fd, mode) int fd, mode; DESCRIPTION
The file whose name is given by path or referenced by the descriptor fd has its mode changed to mode. Modes are constructed by or'ing together some combination of the following, defined in <sys/inode.h>: ISUID 04000 set user ID on execution ISGID 02000 set group ID on execution ISVTX 01000 `sticky bit' (see below) IREAD 00400 read by owner IWRITE 00200 write by owner IEXEC 00100 execute (search on directory) by owner 00070 read, write, execute (search) by group 00007 read, write, execute (search) by others If an executable file is set up for sharing (this is the default) then mode ISVTX (the `sticky bit') prevents the system from abandoning the swap-space image of the program-text portion of the file when its last user terminates. Ability to set this bit on executable files is restricted to the super-user. If mode ISVTX (the `sticky bit') is set on a directory, an unprivileged user may not delete or rename files of other users in that direc- tory. For more details of the properties of the sticky bit, see sticky(8). Only the owner of a file (or the super-user) may change the mode. Writing or changing the owner of a file turns off the set-user-id and set-group-id bits unless the user is the super-user. This makes the system somewhat more secure by protecting set-user-id (set-group-id) files from remaining set-user-id (set-group-id) if they are modified, at the expense of a degree of compatibility. RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
Chmod will fail and the file mode will be unchanged if: [ENOTDIR] A component of the path prefix is not a directory. [EINVAL] The pathname contains a character with the high-order bit set. [ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. [ENOENT] The named file does not exist. [EACCES] Search permission is denied for a component of the path prefix. [ELOOP] Too many symbolic links were encountered in translating the pathname. [EPERM] The effective user ID does not match the owner of the file and the effective user ID is not the super-user. [EROFS] The named file resides on a read-only file system. [EFAULT] Path points outside the process's allocated address space. [EIO] An I/O error occurred while reading from or writing to the file system. Fchmod will fail if: [EBADF] The descriptor is not valid. [EINVAL] Fd refers to a socket, not to a file. [EROFS] The file resides on a read-only file system. [EIO] An I/O error occurred while reading from or writing to the file system. SEE ALSO
chmod(1), open(2), chown(2), stat(2), sticky(8) 4th Berkeley Distribution May 13, 1986 CHMOD(2)
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