Reference: online help

TODO: expand this section

Examples:

 mlr --help
 Usage: mlr [I/O options] {verb} [verb-dependent options ...] {zero or more file names}
 Output of one verb may be chained as input to another using "then", e.g.
   mlr stats1 -a min,mean,max -f flag,u,v -g color then sort -f color
 Please see 'mlr help topics' for more information.
 Please also see https://johnkerl.org/miller6

 mlr sort --help
 Usage: mlr sort {flags}
 Sorts records primarily by the first specified field, secondarily by the second
 field, and so on.  (Any records not having all specified sort keys will appear
 at the end of the output, in the order they were encountered, regardless of the
 specified sort order.) The sort is stable: records that compare equal will sort
 in the order they were encountered in the input record stream.

 Options:
 -f  {comma-separated field names}  Lexical ascending
 -n  {comma-separated field names}  Numerical ascending; nulls sort last
 -nf {comma-separated field names}  Same as -n
 -r  {comma-separated field names}  Lexical descending
 -nr {comma-separated field names}  Numerical descending; nulls sort first
 -h|--help Show this message.

 Example:
   mlr sort -f a,b -nr x,y,z
 which is the same as:
   mlr sort -f a -f b -nr x -nr y -nr z