Originální popis anglicky:
utime, utimes - change access and/or modification times of an inode
Návod, kniha: Linux Programmer's Manual
#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]);
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 */
};
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- 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.
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.
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.
utime: SVr4, SVID, POSIX. SVr4 documents additional error conditions
EFAULT, EINTR, ELOOP, EMULTIHOP, ENAMETOOLONG, ENOLINK, ENOLINK, ENOTDIR.
utimes: BSD 4.3
chattr(1),
stat(2)
