Strings and here document have UNIX line endings on Windows

Question

Both here documents and strings are using UNIX 0x0A line endings on Windows instead of 0x0D0A. How can I get them to be Windows line endings?

PS C:\> $s = @"
>> now
>> is
>> the
>> "@
PS C:\> $s
now
is
the
PS C:\> $s | Format-Hex

   Label: String (System.String) <7B93DCA4>

          Offset Bytes                                           Ascii
                 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
          ------ ----------------------------------------------- -----
0000000000000000 6E 6F 77 0A 69 73 0A 74 68 65                   now�is�the

PS C:\> $s2 = "
>> Now
>> is
>> the
>> "
PS C:\> $s2

Now
is
the

PS C:\> $s2 | Format-Hex

   Label: String (System.String) <33E42D9F>

          Offset Bytes                                           Ascii
                 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F
          ------ ----------------------------------------------- -----
0000000000000000 0A 4E 6F 77 0A 69 73 0A 74 68 65 0A             �Now�is�the�

PS C:\> $PSVersionTable.PSVersion.ToString()
7.3.7

Answer 1

You have 2 ways of doing this:

You can use dos2unix.

Or you can use a regex.

There are multiple regex syntaxes but for powershell it is just -replace '(?<!\r)\n', "`r`n"

Answer 2

I am thinking that what is generally the goal is to get the current platform specific newline sequence used. To accomplish this, I think I will use:

-replace '(?<!\r)\n', [Environment]::NewLine

This seems to be working on Windows, wsl, and Ubuntu.

Answer 3

Your own solution is probably the best approach, as it ensures use of the platform-appropriate newline format on all supported platforms.

Let me complement it with background information.

When defining multiline string literals in PowerShell (both regular string literals and their here-string variants):

• inside a script file (.ps1, .psm1), PowerShell uses the same newline format as the enclosing file.

• interactively - perhaps surprisingly - PowerShell invariably use LF-only newlines ("`n" in PowerShell), on all supported platforms.

In other words, for use in scripts:

• If you want either CRLF (Windows-format, "`r`n") or LF-only (Unix-format, "`n") newlines in multiline string literals, save your script file in that format.

• For cross-platform scripts, use your -replace solution.

  • It will hardly matter in practice, but if you want to avoid unnecessary replacements, you can use the following approach:

    • Save your script with LF-only newlines.

    • Perform a replacement only if necessary, which can then be a literal replacement, via .Replace():

      if ($env:OS -eq 'Windows_NT') { 
        $multiLineStr = $multiLineStr.Replace("`n", "`r`n") 
      }