button command¶
Synopsis¶
button list
button <name>
Description¶
The button command is used to retrieve the status of a button. To show the status of a button with name ‘button1’ you would issue the command
button button1
The status of the button is both written to the console as ON or OFF and set in the return value variable $? as 0 (true) or 1 (false). To retrieve the status of a button with name button1 and to write it to environment variable status1 you would execute the commands
button button1
setenv status1 $?
A list of all available buttons and their status can be displayed using
button list
If a button device has not been probed yet, its status will be shown as <inactive> in the list.
Configuration¶
To use the button command you must specify CONFIG_CMD_BUTTON=y and enable a button driver. The available buttons are defined in the device-tree.
Return value¶
The variable $? takes the following values
| 0 | ON, the button is pressed |
| 1 | OFF, the button is released |
| 0 | button list was shown |
| 1 | button not found |
| 1 | invalid arguments |