utime, utimes — change access and/or modification times of an inode
#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 | times[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
times
[0] refers to
access time, and times
[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.
Search permission is denied for one of the
directories in the path prefix of path
(see also path_resolution(7)),
or buf
is NULL
and the process does not have permission to change the
time stamps (see above).
filename
does not exist.
buf
is not
NULL and the process does not have permission to change
the time stamps.
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.1-2001 marks utimes
()
legacy, which is strange since it provides more functionality
than utime
().
Linux is not careful to distinguish between the
EACCES and EPERM error returns. On the other hand,
POSIX.1-2001 is buggy in its error description for
utimes
().
chattr(1), futimesat(2), stat(2), futimes(3)
|