UTIME(2) Linux Programmer's Manual UTIME(2)
NAME
utime, utimes - change access(2,5) 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(2,5) 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(2,5) and modification times of the file(1,n) are
set(7,n,1 builtins) to the current time.
Changing time(1,2,n) stamps is permitted when: either the process has appro-
priate privileges (Linux: has the CAP_FOWNER capability), or the effec-
tive user ID equals the user ID of the file(1,n), or buf must is NULL and
the process has write(1,2) permission to the file.
The utimbuf structure is:
struct utimbuf {
time_t actime; /* access(2,5) time(1,2,n) */
time_t modtime; /* modification time(1,2,n) */
};
The function utime allows specification of time(1,2,n) stamps with a resolu-
tion of 1 second. The function utimes is similar, but allows a resolu-
tion of 1 microsecond. Here tv[0] refers to access(2,5) time(1,2,n), 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(8,n), -1 is returned, and errno is
set(7,n,1 builtins) appropriately.
ERRORS
EACCES Search permission is denied for one of the directories in(1,8) 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(1,2,n)
stamps (see above).
ENOENT filename does not exist.
EPERM buf is not NULL and the process does not have permission to
change the time(1,2,n) stamps.
EROFS path resides on a read-only file(1,n) system.
NOTES
Linux does not allow changing the time(1,2,n) stamps on an immutable file(1,n), or
setting the time(1,2,n) stamps to something other than the current time(1,2,n) 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(8,n)
returns. On the other hand, POSIX 1003.1-2003 is buggy in(1,8) its error(8,n)
description for utimes.
CONFORMING TO
utime: SVr4, SVID, POSIX. SVr4 documents additional error(8,n) conditions
EFAULT, EINTR, ELOOP, EMULTIHOP, ENAMETOOLONG, ENOLINK, ENOLINK, ENOT-
DIR.
utimes: BSD 4.3
SEE ALSO
chattr(1), stat(1,2)(2)
Linux 2.6.8 2004-10-10 UTIME(2)