#split

Version 0.1.3 behavior is documented here. The support record separates workspace acceptance from exact published MoonX coordinates.

Split a file or stdin into byte-preserving pieces:

moonx cli/split -l 100 input.txt part-
moonx cli/split -b 64K -d --additional-suffix=.bin input.bin chunk-
moonx cli/split -n l/3 input.txt part-
moonx cli/split -n r/2/3 input.txt
moonx cli/split -C 4K input.txt part-

The default is 1000 records per piece and filenames xaa, xab, … -l/--lines changes the record count; -b/--bytes selects a byte count, accepting b, K, M, G, KiB, MiB, GiB, kB, MB and GB multipliers. With no first operand, or -, input comes from stdin; the second operand changes the filename prefix. Unterminated and binary records retain their exact bytes.

-n/--number selects one of these layouts:

Form	Distribution
N	Divide bytes into N pieces; the first size%N pieces receive one extra byte.
K/N	Write only the original Kth byte partition to stdout.
l/N	Keep complete records in the partition containing their starting byte.
l/K/N	Write only records assigned to the original Kth partition.
r/N	Assign complete records cyclically to N pieces.
r/K/N	Write only the Kth round-robin stream to stdout.

N-piece modes create empty files as needed. -e/--elide-empty-files omits them and compresses the generated filename sequence; selected K still refers to the original partition. Byte and line partitioning uses the named regular file size when available, otherwise spools input to an owned temporary file. Round robin reads directly. Empty input in ordinary -l/-b/-C modes creates no output.

-C/--line-bytes=SIZE packs complete records within the byte ceiling, splitting an oversized record only when necessary. It does not fill spare space after a short complete record with the beginning of a long record. The record prefix is spooled rather than retained as a whole in memory. The stream buffer is 64 KiB; temporary disk use for -C is at most SIZE, and unknown-size N-piece input requires a spool of the consumed input.

-d/--numeric-suffixes[=FROM] selects decimal names; -x/--hex-suffixes[=FROM] selects lowercase hexadecimal names. Leading zeroes in FROM do not widen its numeric value. Explicit FROM disables automatic suffix growth. -a/--suffix-length sets a fixed width; zero selects the default. N-piece modes calculate their required width before opening input. --additional-suffix appends literal text after the generated suffix. Exhaustion retains completed pieces. Counts use signed 64-bit arithmetic.

Hexadecimal start letters use ordinary base-16 arithmetic: FROM=a produces 0a,0b,0c. GNU 9.11's frozen implementation indexes outside its alphabet when incrementing a start containing a-f; those memory-dependent names are outside the upstream comparison profile and are not emulated.

--filter=COMMAND runs the existing pure MoonBit shell interpreter once per named piece, with FILE exported and the exact piece bytes on stdin. It accepts the shell language already documented by cli/sh; it does not select a host shell through SHELL. Filter stdout and stderr remain inherited. The catalog classifies split as Restricted because filters can launch external programs. The host authorizes those children; the classification grants no process or filesystem permission. Sequential pieces await EOF and completion before starting the next filter; round-robin filters remain active together. Empty pieces invoke the filter unless -e suppresses them. A successful filter may ignore stdin.

Byte/record streaming uses at most one ordinary output file handle at a time; round-robin files close after each complete record and reopen only for their next record. Round robin retains one name/state entry per visited piece. With a filter, each visited piece instead owns one live pipe and shell task until input ends; their total resources grow with the selected piece count. Filter commands may create further children or allocate their own buffers. This mode preserves live filter input and does not claim a constant-memory or fixed-child-count bound.

Filters own their explicit file writes: split does not pre-create or truncate FILE. Nonzero filter exits propagate with FILE and command diagnostics; actual SIGPIPE termination is distinguished from a normal exit141. A filter cannot be combined with a selected K/N stdout stream. Ordinary existing named outputs remain explicitly refused and unchanged. Read/write/filter failures retain completed output; owned temporary spools are removed.

#Standalone metadata

Standalone --version prints exactly split 0.1.3 and one newline. Standalone --help starts with Usage: split, includes both metadata options, and ends with a newline. Both write to stdout, leave stdin unread, and exit 0. Publication and acceptance are recorded separately.

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