ecli

An Erlang/OTP application providing an online command line interface.

Provides a collection of libraries designed to make it easy to build telecom style command line access to a system. Features:

• Small C program 'ecli' to access the command line via a unix domain socket

• Unix domain socket server to receive connections from the ecli program

• Example implementation - ecli_juniper.erl to show how to build a Juniper style command line interface

• Expansion assistant - library module to provide tab/spc completion of trees of items that include a few standardised attributes (name, children, node type, action).

• Command parser - library module to parse a command line against a tree of items

Status

This code is under active development. None of the APIs are in any way stable and are likely to change. But it does something, and could be fun to play with.

Origin

Much of the tricky stuff comes from edlin.erl of the Erlang/OTP distribution, with more from Stevens and various blog posts.

Why?

Now I don't work for a telecom supplier I have freedom to hack on telecom stuff of my own.

Build

$ rebar3 compile

Run in test mode

$ rebar3 shell

Eshell V10.4  (abort with ^G)
1> application:start(ecli).
ok
2> ecli:open("/var/tmp/mgmtd.cli.socket", ecli_juniper).
{ok,<0.131.0>}
3>

Then attach the cli and poke around:

./_build/default/lib/ecli/priv/ecli

Welcome to the Juniper style CLI
Hit TAB, SPC or ? at any time to see available options

Seans-MacBook> configure

[ok]
Seans-MacBook# <TAB>
show Show configuration
set  Set a configuration parameter
exit Exit configuration mode
Seans-MacBook# exit

[ok]
Seans-MacBook>

Many of the usual command editing shortcuts work as they do in the erlang shell and other typical emacs-ish shells:

CTRL-a - Start of line
CTRL-e - end of line
CTRL-b - backwards character
CTRL-f - forward character
CTRL-h - backward delete character
CTRL-d - forward delete character
CTRL-l - redraw line
CTRL-t - transpose characters
CTRL-k - kill to end of line
CTRL-y - yank killed text
CTRL-w - backwards delete word (buggy right now)

Cursor left right should work
CTRL-left and right - back / forward word

TAB - completion

There are more planned, also to fix multiline bugs

Test

$ rebar3 eunit

Todo

Many things:

• Hook up sigwinch events in cli and pass up to server
• Grab the user details from the unix domain socket and pass to an authorisation callback of some kind.
• Provide a way for cli to connect to different unix domain paths
• Completion of value types - strings, leaf lists, enums
• Use the values extracted from terminfo properly
• CTRL-c handling in the cli program
• CTRL-d to close session (or exit configure mode) if at start of line
• Lots more of the control keys in ecli_edlin.erl need to be hooked up
• cursor back from a second line goes to the wrong place
• proper logging of user commands
• skipping over control sequences in output e.g. coloring
• Pipe command modifiers