How to format a DateTime in PowerShell

I can format the Get-Date cmdlet no problem like this:

$date = Get-Date -format "yyyyMMdd"

But once I've got a date in a variable, how do I format it? The statement below

$dateStr = $date -format "yyyMMdd"

returns this error:

"You must provide a value expression on the right-hand side of the '-f' operator"

Solution 1:

The same as you would in .NET:

$DateStr = $Date.ToString("yyyyMMdd")

Or:

$DateStr = '{0:yyyyMMdd}' -f $Date

Solution 2:

The question is answered, but there is some more information missing:

Variable vs. Cmdlet

You have a value in the $Date variable and the -f operator does work in this form: 'format string' -f values. If you call Get-Date -format "yyyyMMdd" you call a cmdlet with some parameters. The value "yyyyMMdd" is the value for parameter Format (try help Get-Date -param Format).

-f operator

There are plenty of format strings. Look at least at part1 and part2. She uses string.Format('format string', values'). Think of it as 'format-string' -f values, because the -f operator works very similarly as string.Format method (although there are some differences (for more information look at question at Stack Overflow: How exactly does the RHS of PowerShell's -f operator work?).