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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FCHMOD(3P) POSIX Programmer's Manual FCHMOD(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
fchmod — change mode of a file
#include <sys/stat.h>
int fchmod(int fildes, mode_t mode);
The fchmod() function shall be equivalent to chmod() except that
the file whose permissions are changed is specified by the file
descriptor fildes.
If fildes references a shared memory object, the fchmod()
function need only affect the S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP,
S_IROTH, and S_IWOTH file permission bits.
If fildes references a typed memory object, the behavior of
fchmod() is unspecified.
If fildes refers to a socket, the behavior of fchmod() is
unspecified.
If fildes refers to a STREAM (which is fattach()-ed into the file
system name space) the call returns successfully, doing nothing.
Upon successful completion, fchmod() shall return 0. Otherwise,
it shall return -1 and set errno to indicate the error.
The fchmod() function shall fail if:
EBADF The fildes argument is not an open file descriptor.
EPERM The effective user ID does not match the owner of the file
and the process does not have appropriate privileges.
EROFS The file referred to by fildes resides on a read-only file
system.
The fchmod() function may fail if:
EINTR The fchmod() function was interrupted by a signal.
EINVAL The value of the mode argument is invalid.
EINVAL The fildes argument refers to a pipe and the
implementation disallows execution of fchmod() on a pipe.
The following sections are informative.
Changing the Current Permissions for a File
The following example shows how to change the permissions for a
file named /home/cnd/mod1 so that the owner and group have
read/write/execute permissions, but the world only has read/write
permissions.
#include <sys/stat.h>
#include <fcntl.h>
mode_t mode;
int fildes;
...
fildes = open("/home/cnd/mod1", O_RDWR);
fchmod(fildes, S_IRWXU | S_IRWXG | S_IROTH | S_IWOTH);
None.
None.
None.
chmod(3p), chown(3p), creat(3p), fcntl(3p), fstatat(3p),
fstatvfs(3p), mknod(3p), open(3p), read(3p), write(3p)
The Base Definitions volume of POSIX.1‐2017, sys_stat.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 FCHMOD(3P)
Pages that refer to this page: sys_stat.h(0p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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