Welcome PowerShell User! This recipe is just one of the hundreds of useful resources contained in the PowerShell Cookbook.
If you own the book already, login here to get free, online, searchable access to the entire book's content.
If not, the Windows PowerShell Cookbook is available at Amazon, or any of your other favourite book retailers. If you want to see what the PowerShell Cookbook has to offer, enjoy this free 90 page e-book sample: "The Windows PowerShell Interactive Shell".
You want to work with common administrative numbers (that is, kilobytes, megabytes, gigabytes, terabytes, and petabytes) without having to remember or calculate those numbers.
Use PowerShell’s administrative constants (KB, MB, GB, TB, and PB) to help work with these common numbers.
For example, we can calculate the download time (in seconds) of a 10.18 megabyte file over a connection that gets 215 kilobytes per second:
PS > 10.18mb / 215kb 48.4852093023256
PowerShell’s administrative constants are based on powers of two, since they are the type most commonly used when working with computers. Each is 1,024 times bigger than the one before it:
1kb = 1024 1mb = 1024 * 1 kb 1gb = 1024 * 1 mb 1tb = 1024 * 1 gb 1pb = 1024 * 1 tb
Some people (such as hard drive manufacturers) prefer to call numbers based on powers of two “kibibytes,” “mebibytes,” and “gibibytes.” They use the terms “kilobytes,” “megabytes,” and “gigabytes” to mean numbers that are 1,000 times bigger than the ones before them—numbers based on powers of 10.
Although not represented by administrative constants, PowerShell still makes it easy to work with these numbers in powers of 10—for example, to figure out how big a “300 GB” hard drive is when reported by Windows. To do this, use scientific (exponential) notation:
PS > $kilobyte = 1e3 PS > $kilobyte 1000 PS > $megabyte = 1e6 PS > $megabyte 1000000 PS > $gigabyte = 1e9 PS > $gigabyte 1000000000 PS > (300 * $gigabyte) / 1GB 279.396772384644
“Simple Assignment”