CHMODSection: Linux Programmer's Manual (2)
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NAMEchmod, fchmod - change permissions of a file
DESCRIPTIONThe mode of the file given by path or referenced by fildes is changed.
Modes are specified by or'ing the following:
The effective UID of the process must be zero or must match the owner of the file.
If the effective UID of the process is not zero and the group of the file does not match the effective group ID of the process or one of its supplementary group IDs, the S_ISGID bit will be turned off, but this will not cause an error to be returned.
Depending on the file system, set user ID and set group ID execution bits may be turned off if a file is written. On some file systems, only the super-user can set the sticky bit, which may have a special meaning. For the sticky bit, and for set user ID and set group ID bits on directories, see stat(2).
On NFS file systems, restricting the permissions will immediately influence already open files, because the access control is done on the server, but open files are maintained by the client. Widening the permissions may be delayed for other clients if attribute caching is enabled on them.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORSDepending on the file system, other errors can be returned. The more general errors for chmod are listed below:
The general errors for fchmod are listed below:
CONFORMING TOThe chmod call conforms to SVr4, SVID, POSIX, X/OPEN, 4.4BSD. SVr4 documents EINTR, ENOLINK and EMULTIHOP returns, but no ENOMEM. POSIX.1 does not document EFAULT, ENOMEM, ELOOP or EIO error conditions, or the macros S_IREAD, S_IWRITE and S_IEXEC.
The fchmod call conforms to 4.4BSD and SVr4. SVr4 documents additional EINTR and ENOLINK error conditions. POSIX requires the fchmod function if at least one of _POSIX_MAPPED_FILES and _POSIX_SHARED_MEMORY_OBJECTS is defined, and documents additional ENOSYS and EINVAL error conditions, but does not document EIO.
SEE ALSOopen(2), chown(2), execve(2), stat(2)
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Time: 15:05:56 GMT, July 17, 2018