m4: Frozen state
2.4 Command line options for frozen state
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GNU 'm4' comes with a feature of freezing internal state (⇒Frozen
files). This can be used to speed up 'm4' execution when reusing a
common initialization script.
'-F FILE'
'--freeze-state=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'
'--reload-state=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.