writes definitions associated with a symbol to a file in internal Wolfram System format.


writes out definitions associated with all symbols in the specified context.


writes out definitions for several symbols or contexts.


chooses the name of the output file based on the computer system used.

Details and Options

  • DumpSave writes out definitions in a binary format that is optimized for input by the Wolfram Language.
  • Each file has a plain text header identifying its type and contents.
  • Files written by DumpSave can be read by Get.
  • Files written by DumpSave cannot be exchanged between operating systems that differ in $SystemWordLength.
  • DumpSave will not preserve open stream and link objects.
  • Files written by DumpSave conventionally have names that end with .mx.
  • DumpSave works with local objects.
  • DumpSave["package`",] writes a file with a name such as package.mx/(value of $SystemID)/package.mx.
  • You can use DumpSave["file","s"] to write out the definition for the value of a symbol s itself.
  • You can typically read a dump file when you start the Wolfram System by using the initfile commandline option.
  • DumpSave[File["file.mx"],] is also supported.


open allclose all

Basic Examples  (1)

Save all definitions for a function in a binary file:

Set the directory to a place for temporary files:

Save all definitions for f:

Clear definitions for f:

Restore the definitions for f from the file:

Reset to the original directory:

Scope  (1)

Save definitions to a file specified as a File object:

Properties & Relations  (1)

Local objects can be used with DumpSave to save definitions persistently:

Clear definitions for f:

Restore the definitions for f from the local object:

Introduced in 1996
Updated in 2014