m4: Frozen state

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1 2.4 Command line options for frozen state
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1 
11 GNU 'm4' comes with a feature of freezing internal state (⇒Frozen
 files).  This can be used to speed up 'm4' execution when reusing a
1 common initialization script.
1 
1 '-F FILE'
1 '--freeze-state=FILE'
1      Once execution is finished, write out the frozen state on the
1      specified FILE.  It is conventional, but not required, for FILE to
1      end in '.m4f'.
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1 '-R FILE'
1 '--reload-state=FILE'
1      Before execution starts, recover the internal state from the
1      specified frozen FILE.  The options '-D', '-U', and '-t' take
1      effect after state is reloaded, but before the input files are
1      read.
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