NAME
utimes
, futimes
,
utimensat
, futimens
—
set file access and modification
times
SYNOPSIS
#include
<sys/time.h>
int
utimes
(const
char *file, const struct
timeval *times);
int
futimes
(int
fd, const struct timeval
*times);
#include
<sys/stat.h>
#include <fcntl.h>
int
utimensat
(int
fd, const char
*file, const struct
timespec times[2], int
flag);
int
futimens
(int
fd, const struct timespec
times[2]);
DESCRIPTION
The access and modification times of the file named by path or referenced by fd are changed as specified by the argument times.
If times is NULL
,
the access and modification times are set to the current time. The caller
must be the owner of the file, have permission to write the file, or be the
superuser.
If times is non-null, it is assumed to point to an array of two timeval structures. The access time is set to the value of the first element, and the modification time is set to the value of the second element. The caller must be the owner of the file or be the superuser.
In either case, the file status change time is set to the current time.
The
utimensat
()
and
futimens
()
are equivalent to
utimes
()
and
futimes
(),
respectively, with the following differences.
Both
utimensat
()
and
futimens
()
take two timespec values instead of two timeval values. Further, either of
the tv_nsec fields can be set to one of the following
special values defined in
<sys/stat.h>
, in which case
the value of tv_sec is ignored:
UTIME_NOW
- Set the respective timestamp to the greatest value supported that is not greater than the current time.
UTIME_OMIT
- Do not change the respective timestamp.
Additionally, if the path
argument to
utimensat
()
specifies a relative path, the file whose timestamps are changed is
determined relative to the directory associated with file descriptor
fd instead of the current working directory.
If
utimensat
()
is passed the special value AT_FDCWD
(defined in
<fcntl.h>
) in the
fd parameter, the current working directory is
used.
The flag argument is the bitwise OR of zero or more of the following values:
AT_SYMLINK_NOFOLLOW
- If path names a symbolic link, then the timestamps of the symbolic link are changed.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
ERRORS
utimes
() and
utimensat
() will fail if:
- [
EACCES
] - Search permission is denied for a component of the path prefix; or the
times argument is
NULL
and the effective user ID of the process does not match the owner of the file, and is not the superuser, and write access is denied. - [
EFAULT
] - file or times points outside the process's allocated address space.
- [
EIO
] - An I/O error occurred while reading or writing the affected inode.
- [
ELOOP
] - Too many symbolic links were encountered in translating the pathname.
- [
ENAMETOOLONG
] - A component of a pathname exceeded
NAME_MAX
characters, or an entire pathname (including the terminating NUL) exceededPATH_MAX
bytes. - [
ENOENT
] - The named file does not exist.
- [
ENOTDIR
] - A component of the path prefix is not a directory.
- [
EPERM
] - The times argument is not
NULL
and the calling process's effective user ID does not match the owner of the file and is not the superuser. - [
EROFS
] - The file system containing the file is mounted read-only.
Additionally, utimensat
() will fail
if:
- [
EINVAL
] - The value of the flag argument was neither zero nor
AT_SYMLINK_NOFOLLOW
. - [
EBADF
] - The file argument specifies a relative path and the
fd argument is neither
AT_FDCWD
nor a valid file descriptor. - [
ENOTDIR
] - The file argument specifies a relative path and the fd argument is a valid file descriptor but it does not reference a directory.
- [
EACCES
] - The file argument specifies a relative path but search permission is denied for the directory which the fd file descriptor references.
futimes
() and
futimens
() will fail if:
- [
EBADF
] - fd does not refer to a valid descriptor.
- [
EACCES
] - The times argument is
NULL
and the effective user ID of the process does not match the owner of the file, and is not the superuser, and write access is denied. - [
EFAULT
] - times points outside the process's allocated address space.
- [
EIO
] - An I/O error occurred while reading or writing the affected inode.
- [
EPERM
] - The times argument is not
NULL
and the calling process's effective user ID does not match the owner of the file and is not the superuser. - [
EROFS
] - The file system containing the file is mounted read-only.
SEE ALSO
STANDARDS
The utimes
(),
utimensat
(), and futimens
()
functions conform to IEEE Std 1003.1-2008
(“POSIX.1”).
HISTORY
The predecessors of utimes
() were
smdate
() in Version 1
AT&T UNIX, mdate
() in
Version 3 AT&T UNIX, and
utime
() in Version 7
AT&T UNIX; the latter first supported the concept of an access
time in addition to the modification time.
The utimes
() function call appeared in
4.2BSD. The futimes
()
function call appeared in NetBSD 1.2. The
utimensat
() and futimens
()
function calls appeared in OpenBSD 5.0.
CAVEATS
Some filesystems, such as FAT, use the same timestamp for both
modification and file status change; on those filesystems, the file status
change timestamp will not be updated if UTIME_OMIT
is specified for the modification timestamp argument. Similarly, on NFS the
file status change timestamp will not be updated if
UTIME_OMIT
is specified for both the access and the
modification timestamp arguments.