Create Timestamp log in PowerShell

Very often in administrative scripting you will want to create a log file where the filename is a timestamp like 200605201912.log. Since PowerShell is based on .NET Framework objects, we can take advantage of the DateTime object which is obtained by using the Get-Date cmdlet:

PS C:\> get-dateSunday, May 21, 2006 6:47:03 PM
If we create a variable with this cmdlet, we have access to all of the object's properties.

PS C:\> $now=get-date
PS C:\> $now|get-member -membertype properties
TypeName: System.DateTimeName MemberType Definition
---- ---------- ----------
DisplayHint NoteProperty Microsoft.PowerShell.Commands.DisplayHintType
DDate Property System.DateTime Date {get;}
Day Property System.Int32 Day {get;}
DayOfWeek Property System.DayOfWeek DayOfWeek {get;}
DayOfYear Property System.Int32 DayOfYear {get;}
Hour Property System.Int32 Hour {get;}
Kind Property System.DateTimeKind Kind {get;}
Millisecond Property System.Int32 Millisecond {get;}
Minute Property System.Int32 Minute {get;}
Month Property System.Int32 Month {get;}
Second Property System.Int32 Second {get;}
Ticks Property System.Int64 Ticks {get;}
TimeOfDay Property System.TimeSpan TimeOfDay {get;}
Year Property System.Int32 Year {get;}
DateTime ScriptProperty System.Object DateTime {get=if

PS C:\>

With this object we can build a timestamp name by returning the year, month, day and minute properties. We can even go so far as to get second and millisecond if we need that level of precision. To simplify the process, I've written a function called logstamp that will return a timestamp in the form of YearMonthDayMinute.

Function logstamp {
$now=get-Date
$yr=$now.Year.ToString()
$mo=$now.Month.ToString()
$dy=$now.Day.ToString()
$hr=$now.Hour.ToString()
$mi=$now.Minute.ToString()
if ($mo.length -lt 2) {
$mo="0"+$mo #pad single digit months with leading zero
}
if ($dy.length -lt 2) {
$dy="0"+$dy #pad single digit day with leading zero
}
if ($hr.length -lt 2) {
$hr="0"+$hr #pad single digit hour with leading zero
}
if ($mi.length -lt 2) {
$mi="0"+$mi #pad single digit minute with leading zero
}
write-output $yr$mo$dy$hr$mi
}

I'm using the ToString method to convert the datetime object into a string. I do that so that I can check the length property of the month, day and minute variables. If the length is less than 2 then I want to pad it with a leading zero. This makes all my filenames line up neatly.

When I enter this function into PowerShell I can call it at any time and it will return a timestamp string.

PS C:\> logstamp
200605211853

To build a variable for the filename we use something like this:

PS C:\> $stamp=logstamp
PS C:\> $filename=$stamp+".log"
PS C:\> $filename200605211855.log

I can now use the $filename variable to create the log file using the New-Item cmdlet.

PS C:\> new-item . -name $filename -type "file" -value "Audit Log
"Directory: Microsoft.PowerShell.Core\FileSystem::C:\
Mode LastWriteTime Length Name---- ------------- ------
-----a--- 5/21/2006 6:57 PM 9 200605211855.log
PS C:\> get-content $filename
Audit Log
PS C:\>

If you find yourself using this feature, you may want to put the function in your PowerShell profile so that it is always available.

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PowerShell
Scripting

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