Powershell Regex matches leading and trailing spaces

Question

I would like to match with Powershell -replace all $test occurrences that are not quoted (line 3, 4, 6, 7 in the sample below)

1) '$test'
2) test
3) $test
4) foo $test bar
5) foo '$test' bar
6) foo "$test" foo
7) "$test"

I used the regexp below

'[^\'']\$test[^\'']'

but this matches the space too, for example in the line 4, causing the replace to trim them.

How can I match exactly $test when not embedded in single quotes?

Answer 1

You could use the below regex to match $test in the lines 3,4,6,7(ie, $test not enclosed within single quotes)

(?<!\')\$test(?!\')

DEMO

Explanation:

• (?<!\\')\\$test Negative lookahead, which ensures that it won't match the string $test present just after to the single quote.
• (?!\\') And the following character wouldn't be a single quote. Regex engine match the string $test only if the both conditions are satisfied.