Checking for the Existence of a String Value (Strings, Sistema de archivos, PowerShell)

What can you do with the Select-String cmdlet? Well, one thing you can do is determine whether or not a specific string value exists in a text file. For example, suppose the file C:\Scripts\Test.txt is a log file that contains the following information:

You’d like to be able to quickly scan the contents of the file and see whether the word Failed appears anywhere. If it does, that means one of your operations failed; if it doesn’t, that means all of your operations succeeded. (And yes, seeing as how we’re talking about failed operations we do hope you’re not a surgeon.) Here’s how you can do that:

What we’re doing here is using the Get-Content cmdlet to retrieve the contents of the file C:\Scripts\Test.txt. We’re then piping those contents to the Select-String cmdlet and asking Select-String to search for the target string. By adding the -quiet parameter we get back a True if the string is found and nothing if the string is not found. If we leave off the -quiet parameter then Windows PowerShell returns each line in the text file that includes the target string:

Another Select-String parameter that you might find useful is -casesensitive, which performs a case-sensitive search of, in this case, the text file. This particular command will return nothing, meaning that the target string Failed could not be found:

Why couldn’t Failed be found in the text file? That’s easy: based on letter case, there’s no such string in the file. The file contains the string failed with a lowercase f, while the target search string is Failed with an uppercase F. If you change the target string to failed (or remove the -casesensitive parameter) the command returns True.