# Online help

Miller has several online help mechanisms built in.

## Main help

The front door is `mlr --help` or its synonym `mlr -h`. This leads you to `mlr help topics` with its list of specific areas:

GENMD-RUN-COMMAND
mlr --help
GENMD-EOF

GENMD-RUN-COMMAND
mlr help topics
GENMD-EOF

If you know the name of the thing you're looking for, use `mlr help`:

GENMD-RUN-COMMAND
mlr help map
GENMD-EOF

To search by substring, use `mlr help find`:

GENMD-RUN-COMMAND
mlr help find gmt
GENMD-EOF

Etc.

## Command-line flags

This is a command-line version of the [List of command-line flags](reference-main-flag-list.md) page.
See `mlr help flags` for a full listing.

## Per-verb help

This is a command-line version of the [List of verbs](reference-verbs.md) page.
Given the name of a verb (from `mlr -l`) you can invoke it with `--help` or `-h` -- or, use `mlr help verb`:

GENMD-RUN-COMMAND
mlr cat --help
GENMD-EOF

GENMD-RUN-COMMAND
mlr group-like -h
GENMD-EOF

GENMD-RUN-COMMAND
mlr help verb sort
GENMD-EOF

Etc.

## Per-function help

This is a command-line version of the [DSL built-in functions](reference-dsl-builtin-functions.md) page.
Given the name of a DSL function (from `mlr -f`) you can use `mlr help function` for details:

GENMD-RUN-COMMAND
mlr help function append
GENMD-EOF

GENMD-RUN-COMMAND-TOLERATING-ERROR
mlr help function split
GENMD-EOF

GENMD-RUN-COMMAND
mlr help function splita
GENMD-EOF

Etc.

## REPL help

You can use `:h` or `:help` inside the [REPL](repl.md):

<!--- TODO: repl-executor genmd function -->
GENMD-CARDIFY-HIGHLIGHT-ONE
$ mlr repl
Miller v6.0.0-dev REPL for darwin:amd64:go1.16.5
Docs: https://miller.readthedocs.io
Type ':h' or ':help' for on-line help; ':q' or ':quit' to quit.
[mlr] :h
Options:
:help intro
:help examples
:help repl-list
:help repl-details
:help prompt
:help function-names
:help function-details
:help {function name}, e.g. :help sec2gmt
:help {function name}, e.g. :help sec2gmt
[mlr]
GENMD-EOF

## Manual page

If you've gotten Miller from a package installer, you should have `man mlr` producing a traditional manual page.
If not, no worries -- the manual page is a concatenated listing of the same information also available by each of the topics in `mlr help topics`. See also the [Manual page](manpage.md) which is an online copy.
