Powershell replace exact string

Question

I want to replace a simple string "WEEK." (with a dot) in a text file with the string "TEST"

$LOG= "C:\FILE.TXT"
$A= "TEST"
(Get-Content $LOG) | Foreach { $_ -Replace "WEEK.", $A } | Set-Content $LOG;

The problem is that my file has this content:

WEEK_A WEEK.

And when I run my script the result is:

TESTA TEST

and the result that i want is:

WEEK_A TEST

I try with ^ "WEEK." and "^WEEK.$" but it not worked

Can you help me with the regexp? Thanks

====== EDIT ==================

Ok. I try with

$LOG= "C:\FILE.TXT"
$A= "TEST"
(Get-Content $LOG) | Foreach { $_ -Replace "WEEK\.", $A } | Set-Content $LOG;

and seems its works

Answer 1

The reason why this happened is because you have used pattern WEEK. The dot was a problem: in a regular expression world, the dot means "any character". That's why it was replacing both WEEK_ and WEEK. .

When you have added backslash, then the dot was escaped ie. it lost it's special meaning. Thus making it work.