Wolfram Language & System 10.3 (2015)|Legacy Documentation

This is documentation for an earlier version of the Wolfram Language.View current documentation (Version 11.2)


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.

Details and OptionsDetails and Options

  • 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
    MethodAutomaticstream method to use
  • 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 resolves file names according to the procedure described in "Files and Streams".
  • 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 Wolfram System 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.
  • With the default setting BinaryFormat->False, the setting for CharacterEncoding is taken to be .
  • OpenWrite[] always creates a new file that does not already exist, in the directory given by $TemporaryDirectory.
  • With the Method option, the stream is opened using the given input stream method. This overrides the default way that OpenWrite resolves file names.

ExamplesExamplesopen allclose all

Basic Examples  (1)Basic Examples  (1)

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:

Introduced in 1988
| Updated in 2012