eol-convention

Arguments: stream

This function queries the stream's external-format to obtain information on the end-of-line convention being used. It returns two values: a symbol indicating the end-of-line convention and an external-format.

The first returned value is one of the following values:

• :dos: stream's external format is a composed external format with a DOS-style end-of-line convention (carriage-return linefeed at the end of each line).
• :mac: stream's external format is a composed external format with a Macintosh-style end-of-line convention (carriage-return but no linefeed at the end of each line).
• :unix: stream's external format is not a composed external format and has a UNIX-style end-of-line convention (linefeed but no carriage return).
• :anynl-unix: on input, any convention (dos-style carriage-return linefeed, unix-style linefeed and mac-style carriage-return) is correctly read and converted to a Lisp #\newline. On output, #\newlines are converted to linefeed (unix-style).
• :anynl-dos: on input, any convention (dos-style carriage-return linefeed, unix-style linefeed and mac-style carriage-return) is correctly read and converted to a Lisp #\newline. On output, #\newlines are converted to carriage-return linefeed (dos-style).
• :anynl-mac: on input, any convention (dos-style carriage-return linefeed, unix-style linefeed and mac-style carriage-return) is correctly read and converted to a Lisp #\newline. On output, #\newlines are converted to carriage-return (mac-style).

The nature of the second returned value depends on whether stream's external format is or is not a composed external format. If stream's external format is not a composed external format (i.e. the first returned value is :unix), stream's external format is returned as the second returned value. If stream's external format is a composed external format, the second returned value is the composee (which translates Lisp characters to octets) external format. This allows easy construction of a new composed external format based on stream's, if desired. Composed external formats are described in Composed External-Formats.

You can change the end-of-line convention using setf and this function. Specify one of the keywords specified above as the first return value or specify the keyword :anynl. When you specify :anynl, no change is made if the first return value is :anynl-unix, :anynl-dos, or :anynl-mac, and :unix is changed to :anynl-unix, :dos is changed to :anynl-dos, and :mac is changed to :anynl-mac (and the second returned value is changed appropriately).

The :anynl value allows you to have streams read files using any standard end of line convention while still writing files using the machine-appropriate convention. This makes importing files for input much easier.

Modifying the external format of a stream

The eol-convention of a stream may be modified if you explicitly set the external format of a stream and so you may have to reset the eol-convention to the desired value.

Examples

[On Windows]
 (setq s (open "c:/autoexec.bat")) -> stream
 
 ;; The stream is currently set to read/write Ascii 13 followed by Ascii 10
 ;; as/for #\newline.
 (eol-convention s) -> :dos #<external-format ...>
 
 ;; Set the stream so that it reads/writes Ascii 13 as/for #\newline
 (setf (eol-convention s) :mac) -> :mac #<external-format ...>

 ;; Set the stream so that it reads/writes Ascii 10 as/for #\newline
 (setf (eol-convention s) :unix) -> :unix #<external-format ...>

 [On Unix]
 (setq s (open "/etc/passwd"))

 ;; The stream is currently set to read/write Ascii 10 as/for #\newline
 (eol-convention s) -> :unix #<external-format ...>

 ;; Set the stream so that it reads/writes Ascii 13 followed by
 ;; Ascii 10 as/for #\newline.
 (setf (eol-convention s) :dos) -> :dos #<external-format ...>
 
 ;; Set the stream so that it reads/writes Ascii 13 as/for #\newline
 (setf (eol-convention s) :mac) -> :mac #<external-format ...>


 ;; Set the stream so that it reads any standard end of line
 ;; and writes Ascii 13 for #\newline
 (setf (eol-convention s) :anynl-mac) -> :anynl-mac #<external-format ...>

 ;; Set the stream to the UNIX default
 (setf (eol-convention s) :unix)
 ;; Set the stream so that it reads any standard end of line
 ;; and writes Ascii 10 for #\newline
 (setf (eol-convention s) :anynl) -> :anynl-unix #<external-format ...>

See also #\newline discussion.

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This page was not revised from the 10.0 page.
Created 2019.8.20.