EventLog(3) User Contributed Perl Documentation EventLog(3)NAME
Win32::EventLog - Process Win32 Event Logs from Perl
SYNOPSIS
use Win32::EventLog
$handle=Win32::EventLog->new("Application");
DESCRIPTION
This module implements most of the functionality available from the
Win32 API for accessing and manipulating Win32 Event Logs. The access
to the EventLog routines is divided into those that relate to an
EventLog object and its associated methods and those that relate other
EventLog tasks (like adding an EventLog record).
The EventLog Object and its Methods
The following methods are available to open, read, close and backup
EventLogs.
Win32::EventLog->new(SOURCENAME [,SERVERNAME]);
The new() method creates a new EventLog object and returns a handle
to it. This hande is then used to call the methods below.
The method is overloaded in that if the supplied SOURCENAME
argument contains one or more literal '\' characters (an illegal
character in a SOURCENAME), it assumes that you are trying to open
a backup eventlog and uses SOURCENAME as the backup eventlog to
open. Note that when opening a backup eventlog, the SERVERNAME
argument is ignored (as it is in the underlying Win32 API). For
EventLogs on remote machines, the SOURCENAME parameter must
therefore be specified as a UNC path.
$handle->Backup(FILENAME);
The Backup() method backs up the EventLog represented by $handle.
It takes a single arguemt, FILENAME. When $handle represents an
EventLog on a remote machine, FILENAME is filename on the remote
machine and cannot be a UNC path (i.e you must use
C:\TEMP\App.EVT). The method will fail if the log file already
exists.
$handle->Read(FLAGS, OFFSET, HASHREF);
The Read() method read an EventLog entry from the EventLog
represented by $handle.
$handle->Close();
The Close() method closes the EventLog represented by $handle.
After Close() has been called, any further attempt to use the
EventLog represented by $handle will fail.
$handle->GetOldest(SCALARREF);
The GetOldest() method number of the the oldest EventLog record in
the EventLog represented by $handle. This is required to correctly
compute the OFFSET required by the Read() method.
$handle->GetNumber(SCALARREF);
The GetNumber() method returns the number of EventLog records in
the EventLog represented by $handle. The number of the most recent
record in the EventLog is therefore computed by
$handle->GetOldest($oldest);
$handle->GetNumber($lastRec);
$lastRecOffset=$oldest+$lastRec;
$handle->Clear(FILENAME);
The Clear() method clears the EventLog represented by $handle. If
you provide a non-null FILENAME, the EventLog will be backed up
into FILENAME before the EventLog is cleared. The method will fail
if FILENAME is specified and the file refered to exists. Note also
that FILENAME specifies a file local to the machine on which the
EventLog resides and cannot be specified as a UNC name.
$handle->Report(HASHREF);
The Report() method generates an EventLog entry. The HASHREF should
contain the following keys:
"Computer"
The "Computer" field specfies which computer you want the
EventLog entry recorded. If this key doesn't exist, the server
name used to create the $handle is used.
"Source"
The "Source" field specifies the source that generated the
EventLog entry. If this key doesn't exist, the source name
used to create the $handle is used.
"EventType"
The "EventType" field should be one of the constants
"EVENTLOG_ERROR_TYPE"
An Error event is being logged.
"EVENTLOG_WARNING_TYPE"
A Warning event is being logged.
"EVENTLOG_INFORMATION_TYPE"
An Information event is being logged.
"EVENTLOG_AUDIT_SUCCESS"
A Success Audit event is being logged (typically in the
Security EventLog).
"EVENTLOG_AUDIT_FAILURE"
A Failure Audit event is being logged (typically in the
Security EventLog).
These constants are exported into the main namespace by
default.
"Category"
The "Category" field can have any value you want. It is
specific to the particular Source.
"EventID"
The "EventID" field should contain the ID of the message that
this event pertains too. This assumes that you have an
associated message file (indirectly referenced by the field
"Source").
"Data"
The "Data" field contains raw data associated with this event.
"Strings"
The "Strings" field contains the single string that itself
contains NUL terminated sub-strings. This are used with the
EventID to generate the message as seen from (for example) the
Event Viewer application.
Other Win32::EventLog functions.
The following functions are part of the Win32::EventLog package but are
not callable from an EventLog object.
GetMessageText(HASHREF);
The GetMessageText() function assumes that HASHREF was obtained by
a call to "$handle->Read()". It returns the formatted string that
represents the fully resolved text of the EventLog message (such as
would be seen in the Windows NT Event Viewer). For convenience, the
key 'Message' in the supplied HASHREF is also set to the return
value of this function.
If you set the variable $Win32::EventLog::GetMessageText to 1 then
each call to "$handle->Read()" will call this function
automatically.
Example 1
The following example illustrates the way in which the EventLog module
can be used. It opens the System EventLog and reads through it from
oldest to newest records. For each record from the Source EventLog it
extracts the full text of the Entry and prints the EventLog message
text out.
use Win32::EventLog;
$handle=Win32::EventLog->new("System", $ENV{ComputerName})
or die "Can't open Application EventLog\n";
$handle->GetNumber($recs)
or die "Can't get number of EventLog records\n";
$handle->GetOldest($base)
or die "Can't get number of oldest EventLog record\n";
while ($x < $recs) {
$handle->Read(EVENTLOG_FORWARDS_READ|EVENTLOG_SEEK_READ,
$base+$x,
$hashRef)
or die "Can't read EventLog entry #$x\n";
if ($hashRef->{Source} eq "EventLog") {
Win32::EventLog::GetMessageText($hashRef);
print "Entry $x: $hashRef->{Message}\n";
}
$x++;
}
Example 2
To backup and clear the EventLogs on a remote machine, do the following
:-
use Win32::EventLog;
$myServer="\\\\my-server"; # your servername here.
my($date)=join("-", ((split(/\s+/, scalar(localtime)))[0,1,2,4]));
my($dest);
for my $eventLog ("Application", "System", "Security") {
$handle=Win32::EventLog->new($eventLog, $myServer)
or die "Can't open Application EventLog on $myServer\n";
$dest="C:\\BackupEventLogs\\$eventLog\\$date.evt";
$handle->Backup($dest)
or warn "Could not backup and clear the $eventLog EventLog on $myServer ($^E)\n";
$handle->Close;
}
Note that only the Clear method is required. Note also that if the file
$dest exists, the function will fail.
BUGS
None currently known.
The test script for 'make test' should be re-written to use the
EventLog object.
AUTHOR
Original code by Jesse Dougherty for HiP Communications. Additional
fixes and updates attributed to Martin Pauley
<martin.pauley@ulsterbank.ltd.uk>) and Bret Giddings
(bret@essex.ac.uk).
perl v5.14.2 2005-09-17 EventLog(3)
