Powershell regex search and append multiple values

Question

Below I have a ps1 for finding and appending text defined by regex pattern; i.e. from [pattern] to [pattern]Foo. Is there a simpler way to do this for multiple regex patterns, other than defining each regex as pattern2, pattern3, etc. and creating a separate "ForEach" to correspond to every regex? Because that's how I did it, and it works but it looks very rudimentary.

$pattern1 = [regex]'([___)'
$pattern2 = [regex]'([___)'

Get-ChildItem 'C:\\File\\Location\\*.txt' -Recurse | ForEach {
     (Get-Content $_ | 
     ForEach  { $_ -replace $pattern1, ('$1'+'FOO')} | 
     ForEach  { $_ -replace $pattern2, ('$1'+'FOO')}) |
     Set-Content $_
}

BTW [ needs an escape \[ otherwise it's an invalid pattern. Also, use -raw parameter in Get-Content if you're on PowerShell 3 or newer to make processing much faster. — woxxom
– woxxom, Commented Mar 13, 2017 at 22:17
You can chain -replace such as Get-Content $_ -replace $pattern1, '$1FOO' -replace $pattern2, '$1FOO' — TheMadTechnician
– TheMadTechnician, Commented Mar 13, 2017 at 23:06

Wiktor Stribiżew · Accepted Answer · 2017-03-13 22:23:38Z

1

If you are replacing with the same replacement pattern, just use alternation:

$pattern = [regex]'(pattern1|pattern2)'

NOTE: in unanchored alternations, you should watch out for the order of the alternatives: if a shorter branch can match at the same location in string, a longer one - if it is present after the shorter one - won't get tested. E.g. (on|one|ones) will only match on in ones. See more about that in the Remember That The Regex Engine Is Eager.

answered Mar 13, 2017 at 22:23

Wiktor Stribiżew

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