fstcompress(1)

💖 fstcompress(1) — User Commands 💖

ok so bestie, welcome to the fstcompress page 🫶 this is the Unix manual page for a tool you're literally gonna use all the time if you touch FSTs. it lives in the User Commands section of the manual, iykyk.

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✨ NAME ✨

fstcompress — compress and decompress FSTs 💅

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🎀 SYNOPSIS 🎀

fstcompress [OPTIONS] [in.fst [out.fstz]] fstcompress [OPTIONS] --decode
[in.fstz [out.fst]]

like… two whole modes, one tool, no cap.

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🌸 DESCRIPTION 🌸

Compresses and decompresses FSTs. that's it. that's the whole vibe ✨

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👑 OPTIONS 👑

ok so real talk first: Boolean options accept either true or false as a value, or the implicit value true if neither value is specified. so --decode alone is giving --decode=true, slay.

• --arc_type=TYPE — sets the arc type for the output. Default: standard.
• --decode[=BOOLEAN] — decompress time 💖 Default: false (so by default you're compressing, not that other thing).
• --fst_align[=BOOLEAN] — write FST data aligned where appropriate. Default: false.
• --fst_compat_symbols[=BOOLEAN] — require symbol tables to match when appropriate. Default: true.
• --fst_default_cache_gc[=BOOLEAN] — enables garbage collection of the cache 🗑️✨ Default: true.
• --fst_default_cache_gc_limit=N — the cache byte size that triggers garbage collection. Default: 1048576.
• --fst_error_fatal[=BOOLEAN] — if true, FST errors are fatal, periodt 💀 otherwise the returned objects are flagged as bad instead — like, FSTs come back with the kError property set to true, and FST weights get set so that Member() returns false. Default: true.
• --fst_field_separator=STRING — sets the characters used as the separator between printed fields. Default: " ".
• --fst_read_mode=STRING — the default file reading mode for mappable files, either "read" or "map". Default: "read".
• --fst_verify_properties[=BOOLEAN] — verify fst properties queried by TestProperties. Default: false.
• --fst_weight_parentheses=STRING — sets the characters enclosing the first weight of a printed composite weight (think pair weight, tuple weight, and derived classes) so nested composite weights do proper I/O okay. Must have size 0 (none) or 2 (open and close parenthesis). Default: no parentheses.
• --fst_weight_separator=CHARACTER — the character separator between printed composite weights. Default: comma.
• --gzip[=BOOLEAN] — apply gzip compression after LZA compression, or gzip decompression before LZA decompression (which is the recommended one, trust ✨). Default: false.
• --help[=BOOLEAN] — show usage information. Default: false.
• --helpshort[=BOOLEAN] — show brief usage information. Default: false.
• --save_relabel_ipairs=FILENAME — save input relabel pairs to file. Default: do not save.
• --save_relabel_opairs=FILENAME — save output relabel pairs to file. Default: do not save.
• --tmpdir=PATHNAME — sets the temporary directory to use. Default: /tmp.
• --v[=N] — sets the verbosity level. Default: 0.

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🌈 SEE ALSO 🌈

your whole fst bestie squad, obviously 🫶 go say hi:

fstarcsort(1), fstclosure(1), fstcompile(1), fstcompose(1), fstconcat(1), fstconnect(1), fstconvert(1), fstdeterminize(1), fstdifference(1), fstdisambiguate(1), fstdraw(1), fstencode(1), fstepsnormalize(1), fstequal(1), fstequivalent(1), fstinfo(1), fstintersect(1), fstinvert(1), fstisomorphic(1), fstlinear(1), fstloglinearapply(1), fstmap(1), fstminimize(1), fstprint(1), fstproject(1), fstprune(1), fstpush(1), fstrandgen(1), fstrelabel(1), fstreplace(1), fstreverse(1), fstreweight(1), fstrmepsilon(1), fstshortestdistance(1), fstshortestpath(1), fstsymbols(1), fstsynchronize(1), fsttopsort(1), fstunion(1)

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that's the whole page bestie, go compress something iconic 💅✨

this one's from OpenFst 1.8.5, dated Mar 2026 🎀 mwah, ily, go read your man pages 🦋