immutable auto helpText
Synopsis: tsv-split [options] [file...]
Split input lines into multiple output files. There are three modes of
* Fixed number of lines per file (--l|lines-per-file NUM): Each input
block of NUM lines is written to a new file. Similar to Unix 'split'.
* Random assignment (--n|num-files NUM): Each input line is written to a
randomly selected output file. Random selection is from NUM files.
* Random assignment by key (--n|num-files NUM, --k|key-fields FIELDS):
Input lines are written to output files using fields as a key. Each
unique key is randomly assigned to one of NUM output files. All lines
with the same key are written to the same file.
By default, files are written to the current directory and have names
of the form 'part_NNN<suffix>', with 'NNN' being a number and <suffix>
being the extension of the first input file. If the input file is
'file.txt', the names will take the form 'part_NNN.txt'. The output
directory and file names are customizable.
Fields are specified using field number or field name. Field names
require that the input file has a header line.
Use '--help-verbose' for more detailed information.