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.\"     @(#)utimes.2	8.1 (Berkeley) 6/4/93
.\"
.Dd $Mdocdate: September 10 2015 $
.Dt UTIMES 2
.Os
.Sh NAME
.Nm utimes ,
.Nm futimes ,
.Nm utimensat ,
.Nm futimens
.Nd set file access and modification times
.Sh SYNOPSIS
.In sys/time.h
.Ft int
.Fn utimes "const char *file" "const struct timeval *times"
.Ft int
.Fn futimes "int fd" "const struct timeval *times"
.In sys/stat.h
.In fcntl.h
.Ft int
.Fn utimensat "int fd" "const char *file" "const struct timespec times[2]" "int flag"
.Ft int
.Fn futimens "int fd" "const struct timespec times[2]"
.Sh DESCRIPTION
The access and modification times of the file named by
.Fa path
or referenced by
.Fa fd
are changed as specified by the argument
.Fa times .
.Pp
If
.Fa times
is
.Dv 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.
.Pp
If
.Fa 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.
.Pp
In either case, the file status change time is set to the current time.
.Pp
The
.Fn utimensat
and
.Fn futimens
are equivalent to
.Fn utimes
and
.Fn futimes ,
respectively, with the following differences.
.Pp
Both
.Fn utimensat
and
.Fn futimens
take two timespec values instead of two timeval values.
Further, either of the
.Fa tv_nsec
fields can be set to one of the following special values defined in
.In sys/stat.h ,
in which case the value of
.Fa tv_sec
is ignored:
.Pp
.Bl -tag -width UTIME_OMIT -offset indent -compact
.It Dv UTIME_NOW
Set the respective timestamp to the greatest value supported
that is not greater than the current time.
.It Dv UTIME_OMIT
Do not change the respective timestamp.
.El
.Pp
Additionally, if the
.Fa path
argument to
.Fn utimensat
specifies a relative path,
the file whose timestamps are changed is determined relative to
the directory associated with file descriptor
.Fa fd
instead of the current working directory.
.Pp
If
.Fn utimensat
is passed the special value
.Dv AT_FDCWD
(defined in
.In fcntl.h )
in the
.Fa fd
parameter, the current working directory is used.
.Pp
The
.Fa flag
argument is the bitwise OR of zero or more of the following values:
.Pp
.Bl -tag -width AT_SYMLINK_NOFOLLOW -offset indent -compact
.It Dv AT_SYMLINK_NOFOLLOW
If
.Fa path
names a symbolic link, then the timestamps of the symbolic link are changed.
.El
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
.Fn utimes
and
.Fn utimensat
will fail if:
.Bl -tag -width Er
.It Bq Er EACCES
Search permission is denied for a component of the path prefix;
or the
.Fa times
argument is
.Dv 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.
.It Bq Er EFAULT
.Fa file
or
.Fa times
points outside the process's allocated address space.
.It Bq Er EIO
An I/O error occurred while reading or writing the affected inode.
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
.It Bq Er ENAMETOOLONG
A component of a pathname exceeded
.Dv NAME_MAX
characters, or an entire pathname (including the terminating NUL)
exceeded
.Dv PATH_MAX
bytes.
.It Bq Er ENOENT
The named file does not exist.
.It Bq Er ENOTDIR
A component of the path prefix is not a directory.
.It Bq Er EPERM
The
.Fa times
argument is not
.Dv NULL
and the calling process's effective user ID
does not match the owner of the file and is not the superuser.
.It Bq Er EROFS
The file system containing the file is mounted read-only.
.El
.Pp
Additionally,
.Fn utimensat
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value of the
.Fa flag
argument was neither zero nor
.Dv AT_SYMLINK_NOFOLLOW .
.It Bq Er EBADF
The
.Fa file
argument specifies a relative path and the
.Fa fd
argument is neither
.Dv AT_FDCWD
nor a valid file descriptor.
.It Bq Er ENOTDIR
The
.Fa file
argument specifies a relative path and the
.Fa fd
argument is a valid file descriptor but it does not reference a directory.
.It Bq Er EACCES
The
.Fa file
argument specifies a relative path but search permission is denied
for the directory which the
.Fa fd
file descriptor references.
.El
.Pp
.Fn futimes
and
.Fn futimens
will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
.Fa fd
does not refer to a valid descriptor.
.It Bq Er EACCES
The
.Fa times
argument is
.Dv 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.
.It Bq Er EFAULT
.Fa times
points outside the process's allocated address space.
.It Bq Er EIO
An I/O error occurred while reading or writing the affected inode.
.It Bq Er EPERM
The
.Fa times
argument is not
.Dv NULL
and the calling process's effective user ID
does not match the owner of the file and is not the superuser.
.It Bq Er EROFS
The file system containing the file is mounted read-only.
.El
.Sh SEE ALSO
.Xr clock_gettime 2 ,
.Xr stat 2 ,
.Xr utime 3
.Sh STANDARDS
The
.Fn utimes ,
.Fn utimensat ,
and
.Fn futimens
functions conform to
.St -p1003.1-2008 .
.Sh HISTORY
The predecessors of
.Fn utimes
were
.Fn smdate
in
.At v1 ,
.Fn mdate
in
.At v3 ,
and
.Fn utime
in
.At v7 ;
the latter first supported the concept of an access time
in addition to the modification time.
.Pp
The
.Fn utimes
function call appeared in
.Bx 4.2 .
The
.Fn futimes
function call appeared in
.Nx 1.2 .
The
.Fn utimensat
and
.Fn futimens
function calls appeared in
.Ox 5.0 .
.Sh 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
.Dv UTIME_OMIT
is specified for the modification timestamp argument.
Similarly, on NFS the file status change timestamp will not be
updated if
.Dv UTIME_OMIT
is specified for both the access and the modification timestamp arguments.