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utime.2

UTIME

Section: Linux Programmer's Manual (2)
Updated: 2008-08-06
Index Return to Main Contents
 

NAME

utime, utimes - change file last access and modification times  

SYNOPSIS

#include <sys/types.h>

#include <utime.h> int utime(const char *filename, const struct utimbuf *times); #include <sys/time.h> int utimes(const char *filename, const struct timeval times[2]);
 

DESCRIPTION

The utime() system call changes the access and modification times of the inode specified by filename to the actime and modtime fields of times respectively.

If times is NULL, then the access and modification times of the file are set to the current time.

Changing timestamps is permitted when: either the process has appropriate privileges, or the effective user ID equals the user ID of the file, or times is NULL and the process has write permission for the file.

The utimbuf structure is:

struct utimbuf {
    time_t actime;       /* access time */
    time_t modtime;      /* modification time */
};

The utime() system call allows specification of timestamps with a resolution of 1 second.

The utimes() system call is similar, but the times argument refers to an array rather than a structure. The elements of this array are timeval structures, which allow a precision of 1 microsecond for specifying timestamps. The timeval structure is:

struct timeval {
    long tv_sec;        /* seconds */
    long tv_usec;       /* microseconds */
};

times[0] specifies the new access time, and times[1] specifies the new modification time. If times is NULL, then analogously to utime(), the access and modification times of the file are set to the current time.  

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)).
EACCES
times is NULL, the caller's effective user ID does not match the owner of the file, the caller does not have write access to the file, and the caller is not privileged (Linux: does not have either the CAP_DAC_OVERRIDE or the CAP_FOWNER capability).
ENOENT
filename does not exist.
EPERM
times is not NULL, the caller's effective UID does not match the owner of the file, and the caller is not privileged (Linux: does not have the CAP_FOWNER capability).
EROFS
path resides on a read-only file system.
 

CONFORMING TO

utime(): SVr4, POSIX.1-2001. POSIX.1-2008 marks utime() as obsolete.
utimes(): 4.3BSD, POSIX.1-2001.  

NOTES

Linux does not allow changing the timestamps on an immutable file, or setting the timestamps 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.  

SEE ALSO

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

COLOPHON

This page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTES
SEE ALSO
COLOPHON

 

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