This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.1)


Updated In 7 Graphic
opens a file to write output to it, and returns an OutputStream object.
opens a new file in the default area for temporary files on your computer system.
  • OpenWrite deletes any existing contents in a file, and prepares to write output starting at the beginning of the file.
  • The following options can be given:
BinaryFormatFalsewhether to use binary format for the file
CharacterEncodingAutomaticwhat raw character encoding to use
FormatTypeInputFormdefault format for printing expressions
NumberMarks$NumberMarkswhen to use ` marks in approximate numbers
PageWidth78number of character widths per line
TotalWidthInfinitymaximum number of character widths for a single expression
  • On computer systems that support pipes, OpenWrite["!command"] runs the external program specified by command, and opens a pipe to send input to it.
  • If OpenWrite does not succeed in opening a particular file or pipe, it generates a message, and returns $Failed.
  • OpenWrite returns OutputStream["name", n], where name is the full name of a file or command, and n is a serial number that is unique across all streams opened in the current Mathematica session.
  • SetOptions can be used to change the properties of an output stream, after it is already open.
  • Functions like Put and Write automatically open the files or pipes they need, if they are not already open.
Create and open a new stream for writing:
Write an expression to the stream:
Close the stream:
Print the resulting file:
Create and open a new stream for writing:
Click for copyable input
Click for copyable input
Write an expression to the stream:
Click for copyable input
Close the stream:
Click for copyable input
Print the resulting file:
New in 1 | Last modified in 7