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2.4 Command line options for frozen state

GNU m4 comes with a feature of freezing internal state (see Frozen files). This can be used to speed up m4 execution when reusing a common initialization script.

-F file

Once execution is finished, write out the frozen state on the specified file. It is conventional, but not required, for file to end in ‘.m4f’.

-R file

Before execution starts, recover the internal state from the specified frozen file. The options -D, -U, and -t take effect after state is reloaded, but before the input files are read.