utimes() - Unix, Linux System Call
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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 times[2]);
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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 */
};
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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 */
};
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RETURN VALUE
On success, zero is returned. On error, -1 is returned, and
errno is set appropriately.
ERRORS
Tag | Description |
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).
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ENOENT |
filename does not exist.
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EPERM |
buf is not NULL and the process does not have permission to change the time stamps.
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EROFS |
path resides on a read-only file system.
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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.1-2001 marks
utimes() legacy, which is strange since it provides more functionality than
utime().
BUGS
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().
CONFORMING TO
utime(): SVr4, POSIX.1-2001.
utimes(): 4.3BSD
SEE ALSO
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