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utimes (2)

UTIME(2) Linux Programmer's Manual UTIME(2) 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 speci- fied 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 appro- priate privileges (Linux: has the CAP_FOWNER capability), or the effec- tive 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 resolu- tion of 1 second. utimes() The function utimes() is similar, but the times argument allows a reso- lution of 1 microsecond for the 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)), 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) Linux 2007-07-27 UTIME(2)