UTIME(2)

NAME
utime, utimes - change access and/or modification times of an inode

SYNOPSIS
#include <sys/types.h>
#include <utime.h>

int utime(const char *filename, const struct utimbuf *buf);

#include <sys/time.h>

int utimes(const char *filename, const struct timeval tv[2]);

DESCRIPTION
utime changes the access and modification times of the inode specified by filename to the actime and modtime fields of buf respectively. If buf is NULL, then the access and modification times of the file are set to the current time. Changing time stamps is permitted when: either the process has appropriate privileges (Linux: has the CAP_FOWNER capability), or the effective user ID equals the user ID of the file, or buf must is NULL and the process has write permission to the file. The utimbuf structure is:
    struct utimbuf {
            time_t actime;  /* access time */
            time_t modtime; /* modification time */
    };
The function utime allows specification of time stamps with a resolution of 1 second. The function utimes is similar, but allows a resolution of 1 microsecond. Here tv[0] refers to access time, and tv[1] to modification time. The timeval structure is:
    struct timeval {
            long    tv_sec;         /* seconds */
            long    tv_usec;        /* microseconds */
    };

RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

EACCES
    Search permission is denied for one of the directories in the path prefix of path (see also path_resolution(2)), or buf is NULL and the process does not have permission to change the time stamps (see above).

ENOENT
    filename does not exist.

EPERM
    buf is not NULL and the process does not have permission to change the time stamps.

EROFS
    path resides on a read-only file system.

NOTES
Linux does not allow changing the time stamps on an immutable file, or setting the time stamps to something other than the current time on an append-only file. In libc4 and libc5, utimes is just a wrapper for utime and hence does not allow a subsecond resolution. POSIX calls utimes legacy.

BUGS
Linux is not careful to distinguish between the EACCES and EPERM error returns. On the other hand, POSIX 1003.1-2003 is buggy in its error description for utimes.

CONFORMING TO
utime: SVr4, SVID, POSIX. SVr4 documents additional error conditions EFAULT, EINTR, ELOOP, EMULTIHOP, ENAMETOOLONG, ENOLINK, ENOLINK, ENOTDIR.
utimes: 4.3BSD

SEE ALSO
chattr(1), stat(2)