String

Single-line string

"single"

Multi-line string

When single-line string exceeds column number you want, use multi-line string. Leading two spaces are trimmed

''
  this is a 
  linebreak!
''

is equivalent to

"this is a \nlinebreak!"

Multi-line string is typically useful to write shell scripts inside nix.

stdenv.mkDerivation {
  postInstall =
    ''
      mkdir $out/bin $out/etc
      cp foo $out/bin
      echo "Hello World" > $out/etc/foo.conf
      ${if enableBar then "cp bar $out/bin" else ""}
    '';
}

Escaping

To escape in multi-line, prefix with ''

''
  This is a dollar sign:
  ''$
  This is a new line ''\n
  This is a single quote: ''\'
  This is also a single quote: '''
''

String concatenation

"foo" + "bar"

String interpolation

"git path managed by nix: ${pkgs.git}"