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opens a file to append output to it, and returns an OutputStream object.
  • 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, OpenAppend["!command"] runs the external program specified by command, and opens a pipe to send input to it.
  • If OpenAppend does not succeed in opening a particular file or pipe, it generates a message, and returns $Failed.
  • OpenAppend 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.
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