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elua/docs/06_the_elua_shell.txt
Bogdan Marinescu 3eb530b4eb initial import
2008-07-29 11:08:54 +00:00

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06. The eLua shell
================================================================================
After you burn eLua to your board and you connect the board to your terminal
emulator running on the PC, you'll be greeted with the eLua shell prompt, which
allows you to:
- run 'lua' as you would run it from the Linux or Windows command prompt
- upload a Lua source file via XMODEM and execute in on board
- query the eLua version
- get help on shell usage
First you'll need to configure your terminal emulation program to connect to
your eLua board. These are the parameters you'll need to set for your serial
connection:
- speed 115200, 8N1 (8 data bits, no parity, one stop bit)
- no flow control
- newline handling (if available): CR on receive, CR+LF on send
After you setup your terminal program, press the RESET button on the bord.
When you see the "eLua# " prompt, just enter "help" to see the on-line shell
help:
eLua# help
Shell commands:
help - print this help
lua [args] - run Lua with the given arguments
recv - receive a file (XMODEM) and execute it
ver - print eLua version
exit - exit from this shelll
More details about some of the shell commands are presented below.
The "recv" command
================================================================================
To use this, your terminal emulation program must support sending files via the
XMODEM protocol. Both XMODEM with checksum (the original version) and XMODEM
with CRC are supported, but only XMODEM with 128 byte packets is allowed (XMODEM
with 1K packets won't work). The file size that you can upload is limited to 1024
bytes, but this can be easily changed by modifying the "XMODEM_MAX_FILE_SIZE"
macro in src/main.c:
(BEGIN src/main.c)
// Maximum file size that can be received via XMODEM
// Should be a multiple of 128
#define XMODEM_MAX_FILE_SIZE 1024
(END src/main.c)
To use this feature, enter "recv" at the shell prompt. eLua will respond with
"Waiting for file ...". At this point you can send the file to the eLua board
via XMODEM. eLua will receive and execute the file.
The "lua" command
================================================================================
This allows you to start the Lua interpreter with command line parameters, just
as you would do from a Linux or Windows command prompt. This command has some
restrictions:
- the command line can't be longer than 50 chars
- character escaping is not implemented. For example, the next command won't work
because of the \' escape sequences:
eLua# lua -e 'print(\'Hello, World!\')' -i
Press CTRL+Z to exit Lua
lua: (command line):1: unexpected symbol near '\'
However, if you use both '' and "" for string quoting, it will work:
eLua# lua -e 'print("Hello, World")' -i
Press CTRL+Z to exit Lua
Lua 5.1.3 Copyright (C) 1994-2008 Lua.org, PUC-Rio
Hello,World
>