u-boot/doc/usage/askenv.rst
Adarsh Babu Kalepalli a86ed41bff doc/usage: cmd-usage help file for askenv
help file for using askenv cmd is created.
It provides description on the command purpose,
description of arguments,
couple of examples (illustrating command usage),
configuration parameter and
possible return values.

Signed-off-by: Adarsh Babu Kalepalli <opensource.kab@gmail.com>
Add missing entry in doc/usage/index.rst.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2021-06-28 19:57:13 +02:00

87 lines
1.8 KiB
ReStructuredText

.. SPDX-License-Identifier: GPL-2.0+:
askenv command
===============
Synopsis
--------
::
askenv name [message] [size]
Description
-----------
Display message and get environment variable name of max size characters
from stdin.
name
name of the environment variable
message
message is displayed while the command waits for the value to be
entered from stdin.if no message is specified,a default message
"Please enter name:" will be displayed.
size
maximum number of characters that will be stored in environment
variable name.this is in decimal number format (unlike in
other commands where size values are in hexa-decimal). Default
value of size is 1023 (CONFIG_SYS_CBSIZE - 1).
Example
-------
Value of a environment variable env1 without message and size parameters:
::
=> askenv env1;echo $?
Please enter 'env1': val1
0
=> printenv env1
env1=val1
Value of a environment variable env2 with message and size parameters:
::
=> askenv env2 Please type-in a value for env2: 10;echo $?
Please type-in a value for env2: 1234567890123
0
=> printenv env2
env2=1234567890
Value of a environment variable env3 with size parameter only:
::
=> askenv env3 10;echo $?
Please enter 'env3': val3
0
=> printenv env3
env3=val3
Return Value of askenv command, when used without any other arguments:
::
=> askenv;echo $?
askenv - get environment variables from stdin
Usage:
askenv name [message] [size]
- display 'message' and get environment variable 'name' from stdin (max 'size' chars)
1
Configuration
-------------
The askenv command is only available if CMD_ASKENV=y
Return value
------------
The return value $? is set to 0 (true).
If no other arguments are specified (along with askenv), it is set to 1 (false).