Man

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UTIMENSAT(2)              FreeBSD System Calls Manual             UTIMENSAT(2)

NAME
     futimens, utimensat - set file access and modification times

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/stat.h>

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

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

DESCRIPTION
     The access and modification times of the file named by path or referenced
     by fd are changed as specified by the argument times.  The inode-change-
     time of the file is set to the current time.

     If path specifies a relative path, it is relative to the current working
     directory if fd is AT_FDCWD and otherwise relative to the directory
     associated with the file descriptor fd.

     The tv_nsec field of a timespec structure can be set to the special value
     UTIME_NOW to set the current time, or to UTIME_OMIT to leave the time
     unchanged.  In either case, the tv_sec field is ignored.

     If times is non-NULL, it is assumed to point to an array of two timespec
     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.  If times is NULL, this is equivalent to passing
     a pointer to an array of two timespec structures with both tv_nsec fields
     set to UTIME_NOW.

     If both tv_nsec fields are UTIME_OMIT, the timestamps remain unchanged
     and no permissions are needed for the file itself, although search
     permissions may be required for the path prefix.  The call may or may not
     succeed if the named file does not exist.

     If both tv_nsec fields are UTIME_NOW, the caller must be the owner of the
     file, have permission to write the file, or be the super-user.

     For all other values of the timestamps, the caller must be the owner of
     the file or be the super-user.

     The values for the flag argument of the utimensat() system call are
     constructed by a bitwise-inclusive OR of flags from the following list,
     defined in <fcntl.h>:

     AT_SYMLINK_NOFOLLOW
             If path names a symbolic link, the symbolic link's times are
             changed.  By default, utimensat() changes the times of the file
             referenced by the symbolic link.

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.

COMPATIBILITY
     If the running kernel does not support this system call, a wrapper
     emulates it using fstatat(2), futimesat(2) and lutimes(2).  As a result,
     timestamps will be rounded down to the nearest microsecond, UTIME_OMIT is
     not atomic and AT_SYMLINK_NOFOLLOW is not available with a path relative
     to a file descriptor.

ERRORS
     These system calls will fail if:

     [EACCES]           The times argument is NULL, or both tv_nsec values are
                        UTIME_NOW, 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.

     [EFAULT]           The times argument points outside the process's
                        allocated address space.

     [EINVAL]           The tv_nsec component of at least one of the values
                        specified by the times argument has a value less than
                        0 or greater than 999999999 and is not equal to
                        UTIME_NOW or UTIME_OMIT.

     [EIO]              An I/O error occurred while reading or writing the
                        affected inode.

     [EPERM]            The times argument is not NULL nor are both tv_nsec
                        values UTIME_NOW, nor are both tv_nsec values
                        UTIME_OMIT and the calling process's effective user ID
                        does not match the owner of the file and is not the
                        super-user.

     [EPERM]            The named file has its immutable or append-only flag
                        set, see the chflags(2) manual page for more
                        information.

     [EROFS]            The file system containing the file is mounted read-
                        only.

     The futimens() system call will fail if:

     [EBADF]            The fd argument does not refer to a valid descriptor.

     The utimensat() system call will fail if:

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EBADF]            The path argument does not specify an absolute path
                        and the fd argument is neither AT_FDCWD nor a valid
                        file descriptor.

     [EFAULT]           The path argument points outside the process's
                        allocated address space.

     [ELOOP]            Too many symbolic links were encountered in
                        translating the pathname.

     [ENAMETOOLONG]     A component of a pathname exceeded NAME_MAX
                        characters, or an entire path name exceeded PATH_MAX
                        characters.

     [ENOENT]           The named file does not exist.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [ENOTDIR]          The path argument is not an absolute path and fd is
                        neither AT_FDCWD nor a file descriptor associated with
                        a directory.

     [ENOTSUP]          The running kernel does not support this system call
                        and AT_SYMLINK_NOFOLLOW is used with a path relative
                        to a file descriptor.

SEE ALSO
     chflags(2), stat(2), symlink(2), utimes(2), utime(3), symlink(7)

STANDARDS
     The futimens() and utimensat() system calls are expected to conform to
     IEEE Std 1003.1-2008 (``POSIX.1'').

HISTORY
     The futimens() and utimensat() system calls appeared in FreeBSD 10.3.

FreeBSD 11.1-RELEASE-p4        January 17, 2016        FreeBSD 11.1-RELEASE-p4
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