fy-tool(1)
| FY-TOOL(1) | libfyaml | FY-TOOL(1) |
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
| March 15, 2026 |