Sets file access and modification times.
Format
#include <time.h>
int utimes (const char *path, const struct timeval times[2]);
1 – Arguments
path
A pointer to a file.
times
an array of timeval structures. The first array member represents
the date and time of last access, and the second member
represents the date and time of last modification. The times
in the timeval structure are measured in seconds and microseconds
since the Epoch, although rounding toward the nearest second may
occur.
2 – Description
The utimes function sets the access and modification times of the
file pointed to by the path argument to the value of the times
argument. The utimes function allows time specifications accurate
to the microsecond.
If the times argument is a NULL pointer, the access and
modification times of the file are set to the current time. The
effective user ID of the process must be the same as the owner
of the file, or must have write access to the file or appropriate
privileges to use this call in this manner.
Upon completion, utimes marks the time of the last file status
change, st_ctime, for update.
NOTE (Integrity servers, Alpha)
On OpenVMS Alpha and Integrity server systems, the stat,
fstat, utime, and utimes functions have been enhanced to
take advantage of the new file-system support for POSIX
compliant file timestamps.
This support is available only on ODS-5 devices on OpenVMS
Alpha systems beginning with a version of OpenVMS Alpha
after Version 7.3.
Before this change, the stat and fstat functions were
setting the values of the st_ctime, st_mtime, and st_atime
fields based on the following file attributes:
st_ctime - ATR$C_CREDATE (file creation time)
st_mtime - ATR$C_REVDATE (file revision time)
st_atime - was always set to st_mtime because no support
for file access time was available
Also, for the file-modification time, utime and utimes were
modifying the ATR$C_REVDATE file attribute, and ignoring the
file-access-time argument.
After the change, for a file on an ODS-5 device, the stat
and fstat functions set the values of the st_ctime, st_
mtime, and st_atime fields based on the following new file
attributes:
st_ctime - ATR$C_ATTDATE (last attribute modification
time)
st_mtime - ATR$C_MODDATE (last data modification time)
st_atime - ATR$C_ACCDATE (last access time)
If ATR$C_ACCDATE is 0, as on an ODS-2 device, the stat and
fstat functions set st_atime to st_mtime.
For the file-modification time, the utime and utimes
functions modify both the ATR$C_REVDATE and ATR$C_MODDATE
file attributes. For the file-access time, these functions
modify the ATR$C_ACCDATE file attribute. Setting the ATR$C_
MODDATE and ATR$C_ACCDATE file attributes on an ODS-2 device
has no effect.
For compatibility, the old behavior of stat, fstat, utime,
and utimes remains the default, regardless of the kind of
device.
The new behavior must be explicitly enabled by defining the
DECC$EFS_FILE_TIMESTAMPS logical name to "ENABLE" before
invoking the application. Setting this logical does not
affect the behavior of stat, fstat, utime, and utimes for
files on an ODS-2 device.
3 – Return Values
0 Successful execution.
-1 Indicates an error. The file times do not
change and the function sets errno to one of
the following values:
The utimes function will fail if:
o EACCES - Search permission is denied by
a component of the path prefix; or the
times argument is a NULL pointer and the
effective user ID of the process does
not match the owner of the file and write
access is denied.
o ELOOP - Too many symbolic links were
encountered in resolving path.
o ENAMETOOLONG - The length of the path
argument exceeds PATH_MAX, a pathname
component is longer than NAME_MAX, or a
pathname resolution of a symbolic link
produced an intermediate result whose
length exceeds PATH_MAX.
o ENOENT - A component of path does not
name an existing file, or path is an empty
string.
o ENOTDIR - A component of the path prefix is
not a directory.
o EPERM -The times argument is not a NULL
pointer and the calling process's effective
user ID has write-access to the file but
does not match the owner of the file and
the calling process does not have the
appropriate privileges.
o EROFS - The file system containing the file
is read-only.