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.
The lutimes system call 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.
The utimes and lutimes system calls will fail if: