.\" Copyright (c) 1980, 1991, 1993.\"	The Regents of the University of California.  All rights reserved..\".\" Redistribution and use in source and binary forms, with or without.\" modification, are permitted provided that the following conditions.\" are met:.\" 1. Redistributions of source code must retain the above copyright.\"    notice, this list of conditions and the following disclaimer..\" 2. Redistributions in binary form must reproduce the above copyright.\"    notice, this list of conditions and the following disclaimer in the.\"    documentation and/or other materials provided with the distribution..\" 3. All advertising materials mentioning features or use of this software.\"    must display the following acknowledgement:.\"	This product includes software developed by the University of.\"	California, Berkeley and its contributors..\" 4. Neither the name of the University nor the names of its contributors.\"    may be used to endorse or promote products derived from this software.\"    without specific prior written permission..\".\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION).\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF.\" SUCH DAMAGE..\".\"     @(#)chmod.2	8.1 (Berkeley) 6/4/93.\".Dd June 4, 1993.Dt CHMOD 2.Os BSD 4.Sh NAME.Nm chmod ,.Nm fchmod.Nd change mode of file.Sh SYNOPSIS.Fd #include <sys/stat.h>.Ft int.Fn chmod "const char *path" "mode_t mode".Ft int.Fn fchmod "int fd" "mode_t mode".Sh DESCRIPTIONThe function.Fn chmodsets the file permission bitsof the filespecified by the pathname.Fa pathto.Fa mode ..Fn Fchmodsets the permission bits of the specifiedfile descriptor.Fa fd ..Fn Chmodverifies that the process owner (user) either ownsthe file specified by.Fa path(or.Fa fd ) ,oris the super-user.A mode is created from.Em or'dpermission bit masksdefined in.Aq Pa sys/stat.h :.Bd -literal -offset indent -compact#define S_IRWXU 0000700    /* RWX mask for owner */#define S_IRUSR 0000400    /* R for owner */#define S_IWUSR 0000200    /* W for owner */#define S_IXUSR 0000100    /* X for owner */#define S_IRWXG 0000070    /* RWX mask for group */#define S_IRGRP 0000040    /* R for group */#define S_IWGRP 0000020    /* W for group */#define S_IXGRP 0000010    /* X for group */#define S_IRWXO 0000007    /* RWX mask for other */#define S_IROTH 0000004    /* R for other */#define S_IWOTH 0000002    /* W for other */#define S_IXOTH 0000001    /* X for other */#define S_ISUID 0004000    /* set user id on execution */#define S_ISGID 0002000    /* set group id on execution */#define S_ISVTX 0001000    /* save swapped text even after use */.Ed.PpThe.Dv ISVTX(the.Em sticky bit )indicates to the system which executable files are shareable (thedefault) and the system maintains the program text of the filesin the swap area. The sticky bit may only be set by the super useron shareable executable files..PpIf mode.Dv ISVTX(the `sticky bit') is set on a directory,an unprivileged user may not delete or renamefiles of other users in that directory. The sticky bit may beset by any user on a directory which the user owns or has appropriatepermissions.For more details of the properties of the sticky bit, see.Xr sticky 8 ..PpWriting or changing the owner of a fileturns off the set-user-id and set-group-id bitsunless the user is the super-user.This makes the system somewhat more secureby protecting set-user-id (set-group-id) filesfrom remaining set-user-id (set-group-id) if they are modified,at the expense of a degree of compatibility..Sh RETURN VALUESUpon successful completion, a value of 0 is returned.Otherwise, a value of -1 is returned and.Va errnois set to indicate the error..Sh ERRORS.Fn Chmodwill fail and the file mode will be unchanged if:.Bl -tag -width Er.It Bq Er ENOTDIRA component of the path prefix is not a directory..It Bq Er EINVALThe pathname contains a character with the high-order bit set..It Bq Er ENAMETOOLONGA component of a pathname exceeded 255 characters,or an entire path name exceeded 1023 characters..It Bq Er ENOENTThe named file does not exist..It Bq Er EACCESSearch permission is denied for a component of the path prefix..It Bq Er ELOOPToo many symbolic links were encountered in translating the pathname..It Bq Er EPERMThe effective user ID does not match the owner of the file andthe effective user ID is not the super-user..It Bq Er EROFSThe named file resides on a read-only file system..It Bq Er EFAULT.Fa Pathpoints outside the process's allocated address space..It Bq Er EIOAn I/O error occurred while reading from or writing to the file system..El.Pp.Fn Fchmodwill fail if:.Bl -tag -width Er.It Bq Er EBADFThe descriptor is not valid..It Bq Er EINVAL.Fa Fdrefers to a socket, not to a file..It Bq Er EROFSThe file resides on a read-only file system..It Bq Er EIOAn I/O error occurred while reading from or writing to the file system..El.Sh SEE ALSO.Xr chmod 1 ,.Xr open 2 ,.Xr chown 2 ,.Xr stat 2 ,.Xr sticky 8.Sh STANDARDS.Fn Chmodis expected to conform to IEEE Std 1003.1-1988.Pq Dq Tn POSIX ..Sh HISTORYThe.Fn fchmodfunction callappeared in.Bx 4.2 .