---
name: "fstcompress"
section: "1"
platform: "linux"
package: "libfst-tools"
version: "1.8.4-3"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/fstcompress"
---

# fstcompress(1)

compress and decompress FSTs

## NAME

fstcompress - compress and decompress FSTs

## SYNOPSIS

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

## DESCRIPTION

Compresses and decompresses FSTs.

## OPTIONS

Boolean options accept either *true* or *false* as a value, or the implicit value *true* if neither value is specified.

- **--arc\_type**=*TYPE*

  Set the output arc type.  Default: standard.

- **--decode\[=***BOOLEAN***\]**

  **Decompress.  Default: false (compress).**

- **--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\[=***BOOLEAN***\]**

  **Enable garbage collection of cache.  Default: true.**

- **--fst\_default\_cache\_gc\_limit=***N*

  **Set the cache byte size that triggers garbage collection.  Default: 1048576.**

- **--fst\_error\_fatal\[=***BOOLEAN***\]**

  **If true, FST errors are fatal.  Otherwise, returned objects are flagged as bad.** **For example, FSTs are returned with the** *kError* **property set to true, and** **FST weights set so that** *Member()* **returns false.  Default: true.**

- **--fst\_field\_separator=***STRING*

  **Set the characters used as a separator between printed fields.  Default:** **"	 ".**

- **--fst\_read\_mode=***STRING*

  **Set 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*

  **Set the characters enclosing the first weight of a printed composite weight** **(e.g., pair weight, tuple weight, and derived classes) to ensure proper I/O of** **nested composite weights.  Must have size 0 (none) or 2 (open and close** **parenthesis).  Default: no parentheses.**

- **--fst\_weight\_separator=***CHARACTER*

  **Set the character separator between printed composite weights.  Default: comma.**

- **--gzip\[=***BOOLEAN***\]**

  **Apply gzip compression after LZA compression, or gzip decompression before** **LZA decompression (recommended).  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*

  **Set the temporary directory to use.  Default: /tmp.**

- **--v\[=***N***\]**

  **Set the verbosity level.  Default: 0.**

## SEE ALSO

*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)**