Powershell replace text once per line - powershell

Question

I have a Powershell script that I am trying to work out part of it, so the text input to this is listing the user group they are part of. This PS script is supposed to replace the group with the groups that I am assigning them in active directory(I am limited to only changing groups in active directory). My issue is that when it reaches HR and replaces it, it will then proceed to contine and replace all the new but it all so replaces the HR in CHRL, so my groups look nuts right now. But I am looking it over and it doesn't do it with every line. But for gilchrist it will put something in there for the HR in the name. Is there anything can I do to keep it for changing or am I going to have to change my HR to Human Resources? Thanks for the help.
$lookupTable = #{
'Admin' = 'W_CHRL_ADMIN_GS,M_CHRL_ADMIN_UD,M_CHRL_SITE_GS'
'Security' = 'W_CHRL_SECURITY_GS,M_CHRL_SITE_GS'
'HR' = 'M_CHRL_HR_UD,W_CHRL_HR_GS,M_CHRL_SITE_GS'
$original_file = 'c:\tmp\test.txt'
$destination_file = 'c:\tmp\test2.txt'
Get-Content -Path $original_file | ForEach-Object {
$line = $_
$lookupTable.GetEnumerator() | ForEach-Object {
if ($line -match $_.Key)
{
$line = $line -replace $_.Key, $_.Value
}
}
$line
} | Set-Content -Path $destination_file
Get-Content $destination_file
test.txt:
user,group
john.smith,Admin
joanha.smith,HR
john.gilchrist,security
aaron.r.smith,admin
abby.doe,secuity
abigail.doe,admin

Answer 1

Your input appears to be in CSV format (though note that your sample rows have trailing spaces, which you'd have to deal with, if they're part of your actual data).
Therefore, use Import-Csv and Export-Csv to read / rewrite your data, which allows a more concise and convenient solution:
Import-Csv test.txt |
Select-Object user, #{ Name='group'; Expression = { $lookupTable[$_.group] } } |
Export-Csv -NoTypeInformation -Encoding Utf8 test2.txt
Import-Csv reads the CSV file as a collection of custom objects whose properties correspond to the CSV column values; that is, each object has a .user and .name property in your case.
$_.group therefore robustly reports the abstract group name only, which you can directly pass to your lookup hashtable; Select-Object is used to pass the original .user value through, and to replace the original .group value with the lookup result, using a calculated property.
Export-Csv re-converts the custom objects to a CSV file:
-NoTypeInformation suppresses the (usually useless) data-type-information line at the top of the output file
-Encoding Utf8 was added to prevent potential data loss, because it is ASCII encoding that is used by default.
Note that Export-Csv blindly double-quotes all field values, whether they need it or not; that said, CSV readers should be able to deal with that (and Import-Csv certainly does).
As for what you tried:
The -replace operator replaces all occurrences of a given regex (regular expression) in the input.
Your regexes amounts to looking for (case-insensitive) substrings, which explains why HR matches both the HR group name and substring hr in username gilchrist.
A simple workaround would be to add assertions to your regex so that the substrings only match where you want them; e.g.: ,HR$ would only match after a , at the end of a line ($).
However, your approach of enumerating the hashtable keys for each input CSV row is inefficient, and you're better off splitting off the group name and doing a straight lookup based on it:
# Split the row into fields.
$fields = $line -split ','
# Update the group value (last field)
$fields[-1] = $lookupTable[$fields[-1]]
# Rebuild the line
$line = $fields -join ','
Note that you'd have to make an exception for the header row (e.g., test if the lookup result is empty and refrain from updating, if so).

Answer 2

Why don't you load your text file as a CSV file, using Import-CSV and use "," as a delimiter?
This will allow you to have a Powershell Object you can work on. and then export it as text o CSV. if I use your file & lookup table this code may help you :
$file = Import-Csv -Delimiter "," -Path "c:\ps\test.txt"
$lookupTable = #{
'Admin' = 'W_CHRL_ADMIN_GS,M_CHRL_ADMIN_UD,M_CHRL_SITE_GS'
'Security' = 'W_CHRL_SECURITY_GS,M_CHRL_SITE_GS'
'HR' = 'M_CHRL_HR_UD,W_CHRL_HR_GS,M_CHRL_SITE_GS'}
foreach ($i in $file) {
#Compare and replace
...
}
Export-CSV $file -Delimiter ","
You can then iterate over $file and compare and replace. you can also Export-CSV after you're done.