How to send multiple string by stdin in python -

i send string router_status[router]='on' parent code new process

proc[router] = subprocess.popen([sys.executable, os.getcwd() + '/'                                 + router + '.py', router,                                 json.dumps(graph),                                 json.dumps(as_numbers_dict)],                                 shell=false, stderr=true,                                 stdin=subprocess.pipe,                                 stdout=subprocess.pipe)  proc[router].stdin.write(bytes(router_status[router],                                encoding='utf-8') + b'\n') 

and child process

router_status[router]=sys.stdin.readline().strip() path = os.path.expanduser('~' + '/bgp_routers/' + router) open(path + '/router_status.txt', 'w') f:         f.write(router_status[router]) 

but not work! , pass second string router_status[router]='off' process proc[router].stdin.write(bytes(router_status[router], encoding='utf-8')

proc[router].stdin.flush() 

and still not anything!

ok, not familiar arguments passing subprocess.popen() unable check whether correct. know thing or 2 subprocess module , there things consider looking @ code:

• using shell=false not need defined explicitly standard setting (although, if want make explicit reason, allright of course).
• the argument stderr=false incorrect. must either none or subprocess.pipe.

then, since using python3.x docs state that:

warning - use communicate() rather .stdin.write, .stdout.read or .stderr.read avoid deadlocks due of other os pipe buffers filling , blocking child process.

so you'd better of using proc[router].communicate(input="your standard input, meaning stdin")

it states:

popen.stdin - if stdin argument pipe, attribute writeable stream object returned open(). if encoding or errors arguments specified or universal_newlines argument true, stream text stream, otherwise byte stream. if stdin argument not pipe, attribute none.

in case means stdin should indeed byte stream.

overal, guessing should like:

proc[router] = subprocess.popen([sys.executable, os.getcwd() + '/'                                 + router + '.py', router,                                 json.dumps(graph),                                 json.dumps(as_numbers_dict)],                                 stderr=subprocess.pipe,                                 stdin=subprocess.pipe,                                 stdout=subprocess.pipe)  proc[router].stdin.communicate(str(router_status[router]).encode()) 

i still wondering however, why did include:

path = os.path.expanduser('~' + '/bgp_routers/' + router) open(path + '/router_status.txt', 'w') f:         f.write(router_status[router]) 

since unrelated subprocess.popen() statement. write user input textfile, capture latest input btw. if you'd save user input change 'w' 'a' (this put file in append-mode instead of write-mode).