Split specific string from lines via regex - regex

Question

I have been trying to extract certain equal to 40 values get the sixth last word from multiple lines inside a .txt file with PowerShell.
I have code so far :
$file = Get-Content 'c:\temp\file.txt'
$Array = #()
foreach ($line in $file)
{
$Array += $line.split(",")[6]
}
$Array
$Array | sc "c:\temp\export2.txt"
Txt file : (may be duplicate lines such as hostname01)
4626898,0,3,0,POL,INCR,hostname01,xx,1549429809,0000000507,1549430316,xxx,0,40,1,xxxx,51870834,5040,100
4626898,0,3,0,POL,INCR,hostname02,xx,1549429809,0000000507,1549430316,xxx,0,15,1,xxxx,51870834,5040,100
4626898,0,3,0,POL,INCR,hostname03 developer host,xx,1549429809,0000000507,1549430316,xxx,0,40,1,xxxx,51870834,5040,100
4626898,0,3,0,POL,INCR,hostname01,xx,1549429809,0000000507,1549430316,xxx,0,40,1,xxxx,51870834,5040,100
This is what I want :
hostname01
hostname02
hostname03 developer host

Answer 1

This is not a fast solution, but a convenient and flexible one:
Since your text file is effectively a CSV file, you can use Import-Csv.
Since your data is missing is a header row (column names), which we can supply to Import-Csv via its -Header parameter.
Since you're interested in columns number 7 (hostnames) and 14 (the number whose value should be 40), we need to supply column names (of our choice) for columns 1 through 14.
Import-Csv conveniently converts the CSV rows to (custom) objects, whose properties you can query with Where-Object and selectively extract with Select-Object; adding -Unique suppresses duplicate values.
To put it all together:
Import-Csv c:\temp\file.txt -Header (1..14) |
Where-Object 14 -eq 40 |
Select-Object -ExpandProperty 7 -Unique
For convenience we've named the columns 1, 2, ... using a range expression (1..14), but you're free to use descriptive names.
Assuming that c:\temp\file.txt contains your sample data, the above yields:
hostname01
hostname03 developer host
To output to a file, pipe the above to Set-Content, as in your question:
... | Set-Content c:\temp\export2.txt

Answer 2

If the desired field is always the 6th in the line it is easier to split each line and fetch the 6th member:
Get-Content 'c:\temp\file.txt' | Foreach-Object {($_ -split ',')[6]} | Select-Object -Unique

Answer 3

You could use a non-capturing group to look through the string for the correct format and reference the name of your 6 element with the 1st capture group $1:
(?:\d+,\d,\d,\d,[A-Z]+,[A-Z]+,)([a-zA-Z 0-9]+)
Demo here
(?: ) - Specifies a non-capture group (meaning it's not referenced via $1, or $2 like you normally would with a capture group
\d+, (I won't repeat all of these, but) looking for a one or more digits followed by a literal ,.
[A-Z]+, - Finds an all capital letter string, followed by a literal , (this occurs twice).
([a-zA-Z 0-9]+) - The capture group you're looking for, $1, that will capture all characters a-z, A-Z, spaces, and digits up until a character not in this set (in this case, a comma). Giving you the text you're looking for.

Answer 4

Below should work with what you are trying to do
Get-Content 'c:\temp\file.txt' | %{
$_.Split(',')[6]
}| select -Unique