从 Python 调用 lp 导致脚本退出

Question

以下 Python 脚本的任务是拍摄照片，然后将其打印出来。但是，每次脚本成功调用lp后，脚本退出（干净利落，无异常，无解释）

import time
import picamera
import subprocess

def main():
    with picamera.PiCamera() as cam:
        cam.start_preview(alpha=220)
        #cam.resolution = (2592, 1944)
        cam.capture('test.jpg')
    subprocess.check_call("lp -d HP-270 test.jpg")

while True:
    main()
    time.sleep(5.000)

Answer 1

尝试将对 lp 的调用及其参数分离到一个字符串列表中。这就是您将命令和参数传递给 shell 的方式，默认情况下 subprocess.check_call 没有 shell 解释您提供给它的原始字符串。

subprocess.check_call(["lp", "-d", "HP-270", "test.jpg"])

Subprocess library: Frequently Used Arguments

args is required for all calls and should be a string, or a sequence of program arguments. Providing a sequence of arguments is generally > preferred, as it allows the module to take care of any required escaping > and quoting of arguments (e.g. to permit spaces in file names). If passing a single string, either shell must be True (see below) or else the string must simply name the program to be executed without specifying any arguments.

Answer 2

问题是这样的：Subprocess is not compatibile with RPIO

从 Python 调用 lp 导致脚本退出

Call to lp from Python causes script to exit

python

printing

python-2.7

raspberry-pi

raspbian