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UTIMES(2) System Calls Manual UTIMES(2)

utimes, lutimes, futimes, utimens, lutimens, futimens, utimensatset file access and modification times

library “libc”

#include <sys/time.h>

int
utimes(const char *path, const struct timeval times[2]);

int
lutimes(const char *path, const struct timeval times[2]);

int
futimes(int fd, const struct timeval times[2]);

#include <sys/stat.h>

int
utimens(const char *path, const struct timespec times[2]);

int
lutimens(const char *path, const struct timespec times[2]);

int
futimens(int fd, const struct timespec times[2]);

#include <sys/stat.h>
#include <fcntl.h>

int
utimensat(int fd, const char *path, const struct timespec times[2], int flag);

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 super-user.

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. For file systems that support file birth (creation) times (such as UFS2), the birth time will be set to the value of the second element if the second element is older than the currently set birth time. To set both a birth time and a modification time, two calls are required; the first to set the birth time and the second to set the (presumably newer) modification time. Ideally a new system call will be added that allows the setting of all three times at once. The caller must be the owner of the file or be the super-user.

In either case, the inode-change-time of the file is set to the current time.

lutimes() is like utimes() except in the case where the named file is a symbolic link, in which case lutimes() changes the access and modification times of the link, while utimes() changes the times of the file the link references.

utimens(), lutimens(), and futimens() are like utimes(), lutimes(), and futimes() respectively except that time is specified with nanosecond instead of microsecond precision.

utimensat() works the same way as utimens() except if path is relative. In that case, it is looked up from a directory whose file descriptor was passed as fd. Search permission is required on this directory. fd can be set to AT_FDCWD in order to specify the current directory.

When it operates on a symbolic link, utimensat() will change the target's time unless AT_SYMLINK_NOFOLLOW is set in flag. In that later case, the symbolic link's dates are changed.

The nanosecond fields for utimens(), lutimens(), futimens(), and utimensat() can be set to the special value UTIME_NOW to set the current time, or to UTIME_OMIT to let the time unchanged (this allows changing access time but not modification time, and vice-versa).

The utimes(), lutimes(), futimes(), utimens(), lutimens(), futimens(), and utimensat() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

utimes(), lutimes(), utimens(), lutimens(), and utimensat() will fail if:

[]
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 super-user, and write access is denied.
[]
path or times points outside the process's allocated address space.
[]
An I/O error occurred while reading or writing the affected inode.
[]
Too many symbolic links were encountered in translating the pathname.
[]
A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
[]
The named file does not exist.
[]
A component of the path prefix is not a directory.
[]
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 super-user.
[]
The file system containing the file is mounted read-only.

In addition, utimensat() will fail if:

[]
path does not specify an absolute path and fd is neither AT_FDCWD nor a valid file descriptor open for reading or searching.
[]
path is not an absolute path and fd is a file descriptor associated with a non-directory file.

futimes() and futimens() will fail if:

[]
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 super-user, and write access is denied.
[]
fd does not refer to a valid descriptor.
[]
times points outside the process's allocated address space.
[]
An I/O error occurred while reading or writing the affected inode.
[]
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 super-user.
[]
The file system containing the file is mounted read-only.

stat(2), utime(3), symlink(7)

The utimes() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”). It was however marked as legacy in the IEEE Std 1003.1-2004 (“POSIX.1”) revision. futimens() and utimensat() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

The utimes() function call appeared in 4.2BSD. The futimes() function call appeared in NetBSD 1.2. The lutimes() function call appeared in NetBSD 1.3. Birthtime setting support was added in NetBSD 5.0. futimens() and utimensat() functions calls appeared in NetBSD 6.0.

September 14, 2013 NetBSD-7.0.1