utime

Sommaire

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]);

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 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 */
 };

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(7)), 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.

CONFORMING TO

utime(): SVr4, POSIX.1-2001.
utimes(): 4.3BSD

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().

SEE ALSO

chattr(1), futimesat(2), stat(2), futimes(3)