使用PowerShell通过从行首匹配模式从csv文件中提取文本行

Question

I have a CSV file that I need to extract a specific pattern that occurs at the beginning of a line such as:

Line of text:

"555555","A",John"

This works:

Get-Content $CsvFile | Select-String '^"555555"'

This does not:

$idnum = "555555"
Get-Content $CsvFile | Select-String '^"$idnum"'

How do I extract the line when the string is assigned to a variable?

Answer 1

The single-quote in powershell is a literal. So in the second, you're explicitly looking to match "$idnum" . Because you've got double-quotes in your data you'll need to work around them.

Options You can build up double-quotes to get around this

Get-Content $CsvFile | Select-String "^""$idnum"""

Or you can format in a string replacement like this:

Get-Content $CsvFile | Select-String ('^"{0}"' -f $idnum)

Or you can update $idnum to include the double quotes and then the select-string call is much easier to read

$idnum = '"555555"'
Get-Content $CsvFile | Select-String "^$idnum"