utime() - Unix, Linux System Call
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utime() - Unix, Linux System Call

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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.


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.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().


utime(): SVr4, POSIX.1-2001.

utimes(): 4.3BSD


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