我的子进程命令有问题,我喜欢 grep 出与“Online”行匹配的行。
def run_command(command):
p = subprocess.Popen(command,shell=False,
stdout=subprocess.PIPE,
stderr=subprocess.STDOUT)
return iter(p.stdout.readline, b'')
command = 'mosquitto_sub -u example -P example -t ITT/# -v | grep "Online" '.split()
for line in run_command(command):
print(line)
但是我会得到一个错误
Error: Unknown option '|'.
Use 'mosquitto_sub --help' to see usage.
但是当使用 linux shell 运行时
user@server64:~/Pythoniscriptid$ mosquitto_sub -u example -P example -t ITT/# -v | grep "Online"
ITT/C5/link Online
ITT/IoT/tester55/link Online
ITT/ESP32/TEST/link Online
我也尝试了shell = True
,但没有成功,因为我会收到另一个错误,该错误无法识别主题ITT/#
Error: You must specify a topic to subscribe to.
Use 'mosquitto_sub --help' to see usage.
“可能的重复”根本没有帮助我,所以我认为我遇到了不同的问题。我尝试将代码更改为此,但没有得到任何返回
def run_command(command,command2):
p1 = subprocess.Popen(command,stdout=subprocess.PIPE,stderr=subprocess.STDOUT)
p2 = subprocess.Popen(command2,stdin=p1.stdout,stdout=subprocess.PIPE)
return iter(p2.stdout.readline,'')
command = 'mosquitto_sub -u example -P example -t ITT/# -v'.split()
command2 = 'grep Online'.split()
#subprocess.getoutput(command)
for line in run_command(command,command2):
print(line)
最佳答案
当您拆分文本时,列表将如下所示
['mosquitto_sub', ..., 'ITT/#', '-v', '|', 'grep', '"Online"']
当您将此列表传递给 subprocess.Popen 时,文字 '|'
将成为 mosquitto_sub 的参数之一。
如果您使用shell=True
,则必须转义命令中的任何特殊字符,例如#
,例如使用双引号:
import subprocess
command = 'echo -e "ITT/#\\ni am Online\\nbar Online\\nbaz" | grep "Online" '
p = subprocess.Popen(
command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
for line in iter(p.stdout.readline, b''):
print(line)
或者,按照您编写的方式连接管道,但确保迭代直到 b''
,而不是 u''
:
import subprocess
def run_command(command, command2):
p1 = subprocess.Popen(command,stdout=subprocess.PIPE,stderr=subprocess.STDOUT)
p2 = subprocess.Popen(command2,stdin=p1.stdout,stdout=subprocess.PIPE)
return iter(p2.stdout.readline, b'')
command = ['echo', '-e', 'ITT/#\\ni am Online\\nbar Online\\nbaz']
command2 = 'grep Online'.split()
for line in run_command(command,command2):
print(line)
关于python - 无法在子进程命令中使用 grep,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/48419151/