hong zhang wrote:
List,
I have a question of python using echo.
POWER = 14
return_value = os.system('echo 14 > /sys/class/net/wlan1/device/tx_power')
can assign 14 to tx_power
But
return_value = os.system('echo $POWER > /sys/class/net/wlan1/device/tx_power')
return_value is 256 not 0. It cannot assign 14 to tx_power.
What problem is it?
os.system("echo $POWER") returns 0 but
os.system("echo $POWER > /sys/class/net/wlan1/device/tx_power") returns 256.
Did you think that you could say:
POWER = 14
return_value = os.system('echo $POWER >
/sys/class/net/wlan1/device/tx_power')
in a Python script and that would do the same as:
return_value = os.system('echo 14 >
/sys/class/net/wlan1/device/tx_power')
That won't work because 'POWER' exists only in Python and 'echo' is
being run in the (Linux?) shell.
You could try creating the command-line and then passing it to 'system':
return_value = os.system('echo %s >
/sys/class/net/wlan1/device/tx_power' % POWER)
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