Using Regex to replace multiple lines of text in file

Question

Basically, I have a .bas file that I am looking to update. Basically the script requires some manual configuration and I don't want my team to need to reconfigure the script every time they run it. What I would like to do is have a tag like this

<BEGINREPLACEMENT>
'MsgBox ("Loaded")


ReDim Preserve STIGArray(i - 1)
ReDim Preserve SVID(i - 1)

STIGArray = RemoveDupes(STIGArray)
SVID = RemoveDupes(SVID)
<ENDREPLACEMENT>

I am kind of familiar with powershell so what I was trying to do is to do is create an update file and to replace what is in between the tags with the update. What I was trying to do is:

$temp = Get-Content C:\Temp\file.bas
$update = Get-Content C:\Temp\update
$regex = "<BEGINREPLACEMENT>(.*?)<ENDREPLACEMENT>"

$temp -replace $regex, $update
$temp | Out-File C:\Temp\file.bas

The issue is that it isn't replacing the block of text. I can get it to replace either or but I can't get it to pull in everything in between.

Does anyone have any thoughts as to how I can do this?

You need to use -Raw when reading files in and a "(?s)<BEGINREPLACEMENT>.*?<ENDREPLACEMENT>" regex. Also, use escape dollars in dynamic replacement $temp -replace $regex, $update.Replace('$', '$$') — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Dec 10, 2019 at 14:29
Yupp that was it (Reading it in as -Raw and updating regex)! Im not sure why the regex needs to be different though doesn't mine look for anything in between the two tags? — SureThing
– SureThing, Commented Dec 10, 2019 at 14:52
Got it. Well that completely solved my issue. Thanks so much! — SureThing
– SureThing, Commented Dec 10, 2019 at 14:58

Wiktor Stribiżew · Accepted Answer · 2019-12-10 14:58:26Z

1

You need to make sure you read the whole files in with newlines, which is possible with the -Raw option passed to Get-Content.

Then, . does not match a newline char by default, hence you need to use a (?s) inline DOTALL (or "singleline") option.

Also, if your dynamic content contains something like $2 you may get an exception since this is a backreference to Group 2 that is missing from your pattern. You need to process the replacement string by doubling each $ in it.

$temp = Get-Content C:\Temp\file.bas -Raw
$update = Get-Content C:\Temp\update -Raw
$regex = "(?s)<BEGINREPLACEMENT>.*?<ENDREPLACEMENT>"
$temp -replace $regex, $update.Replace('$', '$$')

answered Dec 10, 2019 at 14:58

Wiktor Stribiżew

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