exception de sous-processus python

Question

J'utilise la commande subprocess.check_output pour deux commandes différentes et dans un cas j'ai un sous-processus. CalledProcessError et dans l'autre cas pas mais le programme se bloque. Le dossier gpio482 n'existe pas et la méthode set renvoie l'erreur et la méthode get plante

méthode Get qui attire l'exception:

try: 
    subprocess.check_output("echo 0 > /sys/class/gpio/gpio482/value", shell=True) 
except subprocess.CalledProcessError: 
    log("set state failed.") 
    return "not-writable" 

Get méthode qui s'écrase:

try: 
    state_string = subprocess.check_output("cat /sys/class/gpio/gpio482/value", shell=True) 
except subprocess.CalledProcessError: 
    log("Get state failed.") 
    return "integer", "0" # unknown 

est-il un point que je fais mal ?!

Si je lance le commonds dans la coquille j'ai eu les mêmes messages d'erreur:

>>> subprocess.check_output("cat /sys/class/gpio/gpio482/value", shell=True) 
cat: can't open '/sys/class/gpio/gpio482/value': No such file or directory 
Traceback (most recent call last): 
File "<stdin>", line 1, in <module> 
File "/usr/lib/python2.7/subprocess.py", line 573, in check_output 
raise CalledProcessError(retcode, cmd, output=output) 
subprocess.CalledProcessError: Command 'cat /sys/class/gpio/gpio482/value' 
returned non-zero exit status 1 
>>> 
>>> 
>>> subprocess.check_output("echo 0 > /sys/class/gpio/gpio482/value", 
shell=True) 
/bin/sh: /sys/class/gpio/gpio482/value: No such file or directory 
Traceback (most recent call last): 
File "<stdin>", line 1, in <module> 
File "/usr/lib/python2.7/subprocess.py", line 573, in check_output 
raise CalledProcessError(retcode, cmd, output=output) 
subprocess.CalledProcessError: Command 'echo 0 > 
/sys/class/gpio/gpio482/value' returned non-zero exit status 1 

Answer 1

La fonction deux sont montrés ci-dessous. La fonction set fonctionne bien et j'attrape l'exception mais dans la fonction get je me suis crashé.

def get_uid_light_state(): 
log("get_uid_light_state") 

try: 
    state_string = subprocess.check_output("cat /sys/class/gpio/gpio482/value", shell=True) 
except subprocess.CalledProcessError: 
    log("Get state failed.") 
    return "integer", "0" 

if state_string == "1\n": 
    return "integer", "2" 
elif state_string == "0\n": 
    return "integer", "1" 

def set_uid_light_state(snmptype, state): 
if snmptype != "integer": 
    return "wrong-type" 

if state == "1": 
    cmd_set_state = "echo 0 > /sys/class/gpio/gpio482/value" 
elif state == "2": 
    cmd_set_state = "echo 1 > /sys/class/gpio/gpio482/value" 
else: 
    log("Invalid value for set uid light state") 
    return "wrong-value" 

try: 
    subprocess.check_output(cmd_set_state, shell=True) 
except subprocess.CalledProcessError: 
    log("Set state failed.") 
    return "not-writable" 

return "DONE"