CODEWITHSUNDEEP
regexpowershell
Shane
Shane

Reputation: 43

Regex date parsing

Can someone help me with a regex to pull

Wed Oct 31 from the below

Date:   Wed Oct 31 12:55:00 2018 -0500

Obviously the date will change day to day in the log.

Upvotes: 0

Views: 446

Answers (3)

Don Cruickshank
Don Cruickshank

Reputation: 5938

You've asked for a regular expression but your example already shows a pitfall in the form of a timezone!

Just using a regular expression alone might get you the wrong day when the timezone offset pushes it across midnight. I'd recommend instead using [DateTime]::TryParseExact instead and then using a Date string format to get it into the form you need:

$Line = "Date:   Wed Oct 31 12:55:00 2018 -0500"

[DateTime] $Date = New-Object DateTime

$Success = [DateTime]::TryParseExact($Line,
    "'Date:   'ddd MMM dd HH':'mm':'ss yyyy zzz",
    [System.Globalization.CultureInfo]::InvariantCulture,
    [System.Globalization.DateTimeStyles]::None,
    [ref] $Date)

if ($Success) {
    $Date.ToString("ddd MMM dd")
}

The above example prints out

Wed Oct 31

Upvotes: 7

Lee_Dailey
Lee_Dailey

Reputation: 7479

this aint a regex, but it seems to do the job ... [grin] 

$FullDateString = 'Date: Wed Oct 31 12:55:00 2018 -0500'
# the `.Split()` version doesn't take into account random extra spaces in the source
#    use the next line instead
#$DateString = $FullDateString.Split(' ')[1..3] -join ' '
$DateString = ($FullDateString -split '\s+')[1..3] -join ' '

$DateString

output = Wed Oct 31

what happened above ...

  • split on the spaces
  • took the 2nd thru 4th [1..3] items from the resulting array
  • joined them with a "space" delimiter

you may want to use a more flexible method and 1st convert to a [datetime] object and then use .ToString() with your preferred format.

Upvotes: 2

Drarig29
Drarig29

Reputation: 2245

Give a look here and here. With that, you can find a pretty easy regex to solve your problem!

Here's what I have:

$date = 'Date: Wed Oct 31 12:55:00 2018 -0500'
$date -replace "Date: (\w{3} \w{3} \d{2}) .*", '$1'

I don't know what you really want to do, so just change the regex as you want ;)

Upvotes: 1

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