Here document

In computing, a here document (here-document, here-text, heredoc, hereis, here-string or here-script) is a file literal or input stream literal: it is a section of a source code file that is treated as if it were a separate file. The term is also used for a form of multiline string literals that use similar syntax, preserving line breaks and other whitespace (including indentation) in the text.

Here documents originate in the Unix shell,^[1] and are found in the Bourne shell (sh), C shell (csh),^[2] tcsh (tcsh),^[3] KornShell (ksh), Bourne Again Shell (bash), and Z shell (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. JavaScript also supports this functionality via template literals, a feature added in its 6th revision (ES6). Other high-level languages such as Python, Julia and Tcl have other facilities for multiline strings.

Here documents can be treated either as files or strings. Some shells treat them as a format string literal, allowing variable substitution and command substitution inside the literal.

^ Cite error: The named reference posix was invoked but never defined (see the help page).
^ "Here document - Rosetta Code". rosettacode.org. Archived from the original on 2020-06-29. Retrieved 2017-02-20.
^ Cite error: The named reference Darwin was invoked but never defined (see the help page).

[posix-1] Cite error: The named reference posix was invoked but never defined (see the help page).

[2] "Here document - Rosetta Code". rosettacode.org. Archived from the original on 2020-06-29. Retrieved 2017-02-20.

[Darwin-3] Cite error: The named reference Darwin was invoked but never defined (see the help page).

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Here document

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