Here documents originate in the Unix shell,[1] and are found in sh, csh,[2] tcsh,[3] ksh, bash, and zsh, among others. Here document-style string literals are found in various high-level languages, notably the Perl programming language (syntax inspired by Unix shell) and languages influenced by Perl, such as PHP and Ruby. Other high-level languages such as Python, JavaScript and Tcl have other facilities for multiline strings.