Flashing circuit Python image into spresense

[neo11 0]

Hello,
I was trying to flash spresense with a python image using the command:

./flash_writer -s -c <serial_port> -b 115200 -d -n "./<downloaded_SPK>"

as mentioned on the webpage: https://developer.sony.com/develop/spresense/docs/circuitpython_set_up_en.html

but the terminal shows

bash: ./flash_writer: Permission denied

So I tried to flash with chmod commands as:

chmod u+x ./flash_writer -s -c /dev/ttyUSB0 --b 115200 -d -n "./adafruit-circuitpython-spresense-en_US-7.3.3.spk"

Could anyone please confirm whether chmod approch is correct? Or how can I grant permission to flash_writer?

Thank you
~Nihal

[neo11 0]

The chmod command shows this in the terminal:

chmod: unrecognized option '--b'