在Powershell变量中查找日期

Question

I have parsed text file:

$Sel = select-string -pattern "Date=*" -path D:\\test_file.txt -List

and here is the result:

D:\test_file.txt:3: <aaa="000000" Date="2016-12-05"> <bbbbb="cccc" dddd="20161209" eeee="2016-12-09" fff="ggggg" hhhh="hhh" aaaa="1" bbbb="100" cccc="100">

I have tried to run regex on it

 $regex = "(19|20)[0-9]{2}[- -.](0[1-9]|1[012])[- -.](0[1-9]|[12][0-9]|3[01])"

to parse this again as

select-string -pattern $regex -InputObject $Sel

but that didn't work. Do you have any ideas how to find the date in that above string?

Answer 1

If the date pattern always is in the specified form Date="yyyy-MM-dd" , the most straightforward way is to look for that pattern. No need to worry about 1900's and 2000's at all. Like so,

# Test data
$sel = 'D:\test_file.txt:3:< aaa="000000" Date="2016-12-05" >'

# Let's match date that starts with Date= literal
[regex]$rex = 'Date="(\d{4}-\d{2}-\d{2})"'

# Print the result if matched
if($rex.Match($sel).groups.count -eq 2) {
    $rex.Match($sel).groups[1].value
}

Answer 2

This should be correct:

$sel -match $regex
$date = $matches[0]