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M4sh, pronounced “mash”, is aiming at producing portable Bourne shell scripts. This name was coined by Lars J. Aas, who notes that, according to the Webster's Revised Unabridged Dictionary (1913):
Mash \Mash\, n. [Akin to G. meisch, maisch, meische, maische, mash, wash, and prob. to AS. miscian to mix. See “Mix”.]
- A mass of mixed ingredients reduced to a soft pulpy state by beating or pressure...
- A mixture of meal or bran and water fed to animals.
- A mess; trouble. [Obs.] –Beau. & Fl.
M4sh reserves the M4 macro namespace ‘^_AS_’ for internal use, and the namespace ‘^AS_’ for M4sh macros. It also reserves the shell and environment variable namespace ‘^as_’, and the here-document delimiter namespace ‘^_AS[A-Z]’ in the output file. You should not define your own macros or output shell code that conflicts with these namespaces.