I find it a little ironic that although I like efficiency, structure and order I'm fascinated with randomness. In today's Friday Fun I want to explore a few ways you might incorporate randomness into your PowerShell scripting. Perhaps you need a random number between 100 and 500. Or a string for file name. There are many paths so let's (randomly) take this one.<\/p>\n
Number Namer<\/strong> [cc lang=\"PowerShell\"] By default the cmdlet returns a number between 0 and 2,147,483,647. But you can set the minimum and maximum values to limit the range.<\/p>\n [cc lang=\"PowerShell\"] I also like that you can tell the cmdlet to return X number of random numbers, but for that you need to pipe in the collection of numbers.<\/p>\n [cc lang=\"PowerShell\"] Strings and Filenames<\/strong> [cc lang=\"Powershell\"] This works great if you want the temp file in your temp folder. But what if you want to create the random or temp file in a different directory. One way might be to use the GetRandomFileName() method.<\/p>\n [cc lang=\"PowerShell\"] I used Join-Path to create a proper path with the folder and random file name. I always recommend Join-Path to construct file paths instead of concatenation.<\/p>\n But what if you want a random character string without the extension or of a different length? You could use the GetRandomFileName() method and parse the string. I decided to try something else and put together a short function to generate a random string of a user specified length.<\/p>\n [cc lang=\"PowerShell\"] $ofs=\"\" The function takes a source string as a parameter, or you can define a default as I've done in the function. The other parameter is the length of the string. The main part of the function turns the string into a character array and then pipes it to Get-Random to retrieve the specified number of characters. The result is saved to the variable, $NewString. Notice that I have specifically cast this as a string. If I didn't, then $NewString would be an array of random characters. But there's one other trick here. Whenever you convert an array to a string, the output field separator is used between each element. This is stored in the $ofs automatic variable. The default is a space. In my function, I set it to basically nothing, so that the characters form a single string.<\/p>\n [cc lang=\"PowerShell\"] Let's wrap this discussion up with total chaos and get a random number of strings with varying (and random length). I crammed everything into a one line expression. The first part defines a range of numbers from 1 to a random number between 5 and 10. These numbers act as counters for the ForEach construct which calls the New-RandomString function specifying a string of a random length between 1 and 10.<\/p>\n
\nTo get a random number is pretty easy using the Get-Random cmdlet.<\/p>\n
\nPS C:\\> get-random
\n729751216
\n[\/cc]<\/p>\n
\nPS C:\\> get-random -min 100 -max 500
\n384
\n[\/cc]<\/p>\n
\nPS C:\\> 100..500 | Get-Random -count 5
\n365
\n442
\n171
\n454
\n111
\n[\/cc]<\/p>\n
\nI expect that many of you have seen this technique to generate a random and temporary filename.<\/p>\n
\nPS C:\\> [system.io.path]::getTempfilename()
\nC:\\Users\\Jeff\\AppData\\Local\\Temp\\tmp8F7F.tmp
\n[\/cc]<\/p>\n
\nPS C:\\> $f=[system.io.path]::GetRandomFileName()
\nPS C:\\> $p=Join-Path \"c:\\work\" $f
\nPS C:\\> $p
\nc:\\work\\d1gsg31u.qoc
\n[\/cc]<\/p>\n
\nFunction New-RandomString {
\n Param([string]$source=\"123abcDEFg45hijk67MNO890\",[int]$Length=7)<\/p>\n
\n [string]$NewString=$source.ToCharArray() | Get-Random -count $length
\n write-Output $NewString
\n}
\n[\/cc]<\/p>\n
\nPS C:\\> new-randomstring -Length 10
\nO5D18E72cj
\n[\/cc]<\/p>\n
\n[cc lang=\"PowerShell\"]
\nPS C:\\> 1..(Get-Random -min 5 -max 10) | foreach {New-RandomString -length (Get-Random -min 1 -max 10)}
\nN7
\nEk7i31Db
\nb60
\nOc6F
\naO
\n8F4
\n78
\n9N4O5
\n3i19OFkj0
\n[\/cc]<\/p>\n