--- name: "fy-tool" section: "1" platform: "linux" package: "libfyaml" version: "0.9.6-3" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/fy-tool" --- # fy-tool(1) fy-tool documentation ## NAME fy-tool - fy-tool documentation ## SYNOPSIS **fy-tool** \[*OPTIONS*\] \[\<*file*\> …\] **fy-dump** \[*OPTIONS*\] \[\<*file*\> …\] **fy-testsuite** \[*OPTIONS*\] \<*file*\> **fy-filter** \[*OPTIONS*\] \[-f *FILE*\] \[\<*path*\> …\] **fy-join** \[*OPTIONS*\] \[-T *PATH*\] \[-F *PATH*\] \[-t *PATH*\] \[\<*file*\> …\] **fy-ypath** \[*OPTIONS*\] \<*ypath-expression*\> \[\<*file*\> …\] **fy-compose** \[*OPTIONS*\] \[\<*file*\> …\] **fy-b3sum** \[*OPTIONS*\] \[\<*file*\> …\] ## DESCRIPTION **fy-tool** is the libfyaml command-line front-end for parsing, rewriting, querying, joining, testing and hashing YAML and JSON data. The executable changes behaviour either by the invoked program name (**fy-dump**, **fy-testsuite**, **fy-filter**, **fy-join**, **fy-ypath**, **fy-compose**, **fy-b3sum**) or by an explicit mode-select option such as **--dump** or **--filter**. The default mode is **dump**. ## OPTIONS General options - **-h, --help** Display the built-in help message. - **-v, --version** Display the libfyaml version. - **-q, --quiet** Suppress informational and non-fatal diagnostic output. - **-d LEVEL, --debug-level LEVEL** Set the minimum diagnostic severity emitted by the library. The default is **3** (warning level). - **-C MODE, --color MODE** Control ANSI color output. Supported values are **on**, **off**, and **auto**. The default is **auto**. - **-V, --visible** Make spaces, tabs, and line breaks visible in text output. - **--dry-run** Parse the input but suppress normal output generation. Diagnostic options - **--disable-diag MODULE** Disable diagnostic output for the named module. - **--enable-diag MODULE** Enable diagnostic output for the named module. - **--show-diag OPTION** Show the named diagnostic field. Supported values are **source**, **position**, **type**, and **module**. - **--hide-diag OPTION** Hide the named diagnostic field. Parser options - **-I DIR, --include DIR** Add **DIR** to the input include search path. - **-j MODE, --json MODE** Select JSON input handling. Supported values are **no**, **force**, and **auto**. The default is **auto**. - **-r, --resolve** Resolve anchors and merge keys while parsing. - **--yaml-1.1** Force YAML 1.1 rules when the input does not declare a version. - **--yaml-1.2** Force YAML 1.2 rules when the input does not declare a version. - **--yaml-1.3** Force YAML 1.3 rules when the input does not declare a version. - **-l, --follow** Follow aliases during path traversal and related path-based operations. - **--sloppy-flow-indentation** Accept relaxed indentation rules in flow mode. - **--prefer-recursive** Prefer recursive algorithms over iterative ones. - **--ypath-aliases** Enable alias processing for ypath evaluation. - **--allow-duplicate-keys** Allow duplicate mapping keys. - **--collect-errors** Collect multiple parsing errors before reporting failure. - **--disable-accel** Disable parser/emitter acceleration features. - **--disable-buffering** Disable stdio buffering and use direct file-descriptor reads. - **--disable-mmap** Disable memory-mapped input. - **--disable-depth-limit** Disable the normal nesting-depth limit. Emitter options - **-i INDENT, --indent INDENT** Set the output indentation width. The default is **2**. - **-w WIDTH, --width WIDTH** Set the preferred output width. Use **inf** for no width limit. The default is **80**. - **-m MODE, --mode MODE** Select the output style. Supported values are **original**, **block**, **flow**, **flow-oneline**, **json**, **json-tp**, **json-oneline**, **dejson**, **pretty**, **flow-compact**, and **json-compact**. - **-s, --sort** Sort mapping keys before emitting output. - **-c, --comment** Preserve and emit comments where supported. - **--strip-labels** Strip anchors and aliases from emitted output. - **--strip-tags** Strip emitted tags. - **--strip-doc** Strip document start and end markers. - **--strip-empty-kv** Omit keys whose values are empty or null. - **--null-output** Suppress normal output generation. - **--no-ending-newline** Do not append a final trailing newline. - **--preserve-flow-layout** Preserve single-line flow collection layout when possible. - **--indented-seq-in-map** Indent block sequences that appear inside block mappings. - **--streaming** Use streaming output mode. This is the default. - **--no-streaming** Disable streaming output mode. - **--recreating** Recreate streaming events instead of passing them through directly. Testsuite options - **--disable-flow-markers** Omit testsuite flow markers. - **--disable-doc-markers** Omit testsuite document markers. - **--disable-scalar-styles** Omit testsuite scalar-style markers. - **--document-event-stream** Build a document first and then generate the event stream from it. - **--tsv-format** Emit testsuite output in TSV format. Input options - **-f FILE, --file FILE** Read from **FILE** instead of standard input where the selected mode uses a single input source. If **FILE** begins with **\>**, the remaining text is treated as literal input content. Join options - **-T PATH, --to PATH** Join into **PATH**. The default is **/**. - **-F PATH, --from PATH** Take joined input from **PATH**. The default is **/**. - **-t PATH, --trim PATH** Emit only **PATH** from the joined result. The default is **/**. YPATH options - **-F PATH, --from PATH** Start evaluation from **PATH**. The default is **/**. - **--dump-pathexpr** Dump the parsed path expression before evaluation. - **--noexec** Parse the expression but do not execute it. Compose options - **--dump-path** Dump the path while composing a document. B3SUM options - **--b3sum** Enable BLAKE3 hashing mode. - **--derive-key CONTEXT** Use key-derivation mode with **CONTEXT**. - **--no-names** Omit file names from checksum output. - **--raw** Emit raw digest bytes. - **--length N** Emit only **N** output bytes, up to the BLAKE3 maximum. - **--check** Verify checksums read from input files. - **--keyed** Use keyed hashing, reading the secret key from standard input. - **--backend BACKEND** Select the BLAKE3 backend implementation. - **--list-backends** List available BLAKE3 backends. - **--num-threads N** Set the worker-thread count. **0** means automatic selection and **-1** disables threaded hashing. - **--file-buffer N** Set the per-file I/O buffer size. - **--mmap-min-chunk N** Set the minimum chunk size used for memory-mapped hashing input. - **--mmap-max-chunk N** Set the maximum chunk size used for memory-mapped hashing input. Modes - **--dump** Select dump mode. This is the default and also the mode used by **fy-dump**. - **--testsuite** Select testsuite mode. This is also the mode used by **fy-testsuite**. - **--filter** Select filter mode. This is also the mode used by **fy-filter**. - **--join** Select join mode. This is also the mode used by **fy-join**. - **--ypath** Select ypath query mode. This is also the mode used by **fy-ypath**. - **--scan-dump** Select the internal scan-dump mode. - **--parse-dump** Select the internal parse-dump mode. - **--compose** Select composer-driver dump mode. This is also the mode used by **fy-compose**. - **--yaml-version-dump** Print YAML version information. ## EXAMPLES Dump a YAML file back out using the default emitter mode: ``` $ fy-dump invoice.yaml ``` Resolve anchors and strip labels from the result: ``` $ fy-dump -r --strip-labels simple-anchors.yaml ``` Read literal input text via **--file**: ``` $ fy-filter --file \">foo: bar\" / ``` Select data from a file using a path expression: ``` $ fy-filter --file simple-anchors.yaml /baz/bar ``` Join two root mappings into a single document: ``` $ fy-join simple-anchors.yaml invoice.yaml ``` Generate testsuite event output: ``` $ fy-testsuite invoice.yaml ``` List available BLAKE3 backends: ``` $ fy-b3sum --list-backends ``` ## AUTHOR Pantelis Antoniou \<*pantelis.antoniou@konsulko.com*\> ## BUGS - • The only supported input and output character encoding is UTF8. - • Sorting does not respect language settings. - • There is no way for the user to specific a different coloring scheme. ## SEE ALSO **libfyaml(3)** ## COPYRIGHT 2019-2026, Pantelis Antoniou