Regex a binary with GC in PowerShell

Question

Question: What PowerShell regex pattern will return an output like Bash's string command?

I found an article on gc and Select-String: Episode #137: Free-base64-ing. http://blog.commandlinekungfu.com/2011/03/episode-137-free-base64-ing.html

I tried a number of regex patterns from a previous question: Regular Expression for alphanumeric and underscores. Regular Expression for alphanumeric and underscores

If I run in Bash: strings --all myfile.bin Results: 52939 lines of character strings.

gc .\myfile.bin | Select-String -AllMatches "^[a-zA-Z0-9_]*$" Results: a number of blank lines.

gc .\myfile.bin | Select-String -AllMatches "^\w*$" Results: 9 lines of characters and a number of blank lines.

gc .\myfile.bin | Select-String -AllMatches "^\w*$" Results: 9 lines of characters.

gc .\myfile.bin | Select-String -AllMatches "[A-Za-z0-9_]" Results: Pretty much the entire file, unprintable characters and all.

gc .\myfile.bin | Select-String -AllMatches "^[\p{L} \p{Nd}_]+$" Results: 20 lines of characters.

So what's the regex trick that I am missing?

Are you sure the Regex portion is the intersting bit? It looks like strings is doing a lot of heavy lifting. — Guvante
– Guvante, Commented Dec 17, 2012 at 22:13

Ansgar Wiechers · Accepted Answer · 2012-12-17 22:57:49Z

1

You're missing that binary files don't consist of "lines" in the way text files do. Therefore ^ and $ won't do you any good here.

While arguably not the most elegant solution, something like this might do:

cat .\myfile.bin `
  | % { $_ -replace '[^\w\d ]', "`n" } `
  | % { $_.Split("`n") } `
  | ? { $_ -match '.{3,}' } `
  | % { $_.Trim() }

Or, you could use Sysinternals' strings utility.

answered Dec 17, 2012 at 22:57

Ansgar Wiechers

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user265537 · Accepted Answer · 2012-12-19 12:27:36Z

0

As mentioned, the lack of line breaks will prevent RegEx from working. Microsoft Sysinternals' strings utility is a good solution.

If you need a native PowerShell solution, ping me. I wrote a Get-Strings cmdlet in C# that does ASCII (UTF8) and Unicode (UTF16) string extraction from binaries. It is not as fast as Sysinternals, but does have the advantage of putting the output into the PowerShell pipeline.

answered Dec 19, 2012 at 12:27

user265537

1 Comment

user1911221 Over a year ago

Yea buddy!! Thats it. I needed it in the pipeline. Thanks J Wolf.

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