CODEWITHSUNDEEP
regexwindowspowershell
shearlynot
shearlynot

Reputation: 81

Regex to remove string after file extension

I'm using PowerShell to query for a service path from which results should resemble C:\directory\sub-directory\service.exe

Some results however also include characters after the .exe file extension, for example output may resemble one of the following:

i.e. ThisTextNeedsRemoving may be proceeded by a space, hyphen or forward slash.

I can use the regex -replace '($*.exe).*' to remove everything after, but including the .exe file extension, but how do I keep the .exe in the results?

Upvotes: 2

Views: 1254

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627343

Using lookbehind is possible, but note that lookbehinds are only necessary when you need to specify some rather complex condition or to obtain overlapping matches. In most cases, when you can do without a lookbehind, you should consider using a non-lookbehind solution because it is rather a costly operation. It is easier to check once if the current character is not a whitespace than to also check if each of these symbols is preceded with something else. Or a whole substring, or a more complext pattern.

Thus, I'd suggest using a solution based on capturing mechanism, with a backreference in the replacement part to restore the captured substring in the result:

$s -replace '^(\S+\.exe) .*','$1'

or - for paths containing spaces and not inside double quotes:

$s -replace '^(.*?\.exe) .*','$1'

Explanation:

  • ^ - start of string
  • (\S+\.exe) - one or more character other than whitespace (\S+) (or any characters other than a newline, any amount, as few as possible, with .*?) followed with a literal . and exe
  • .* - a space and then any number of characters other than a newline.

enter image description here

Upvotes: 2

briantist
briantist

Reputation: 47862

You can use a look-around:

$txt = 'C:\directory\sub-directory\service.exe /ThisTextNeedsRemoving'

$txt -replace '(?<=\.exe).+', ''

This uses a look-behind which is a zero-width match so it doesn't get replaced.

Regular expression visualization

Debuggex Demo

Upvotes: 5

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