Python3/Linux - 在默认编辑器中打开文本文件并等待完成

Question

我需要等到用户在默认图形应用程序(Debian 和衍生版)中完成对文本文件的编辑。

如果我将 xdg-open 与 subprocess.call(通常等待)一起使用，它将在编辑器中打开文件后继续。我假设是因为 xdg-open 本身异步启动了编辑器。

通过检索文本/纯 mime 类型的启动器并将其与 Gio.DesktopAppInfo.new 一起使用以获取编辑器的命令，我终于获得了或多或少的工作代码。如果编辑器尚未打开，则在编辑器仍处于打开状态时流程结束。

我添加了检查 process.pid 和轮询进程的解决方案。两者都以无限循环结束。

等待进程完成似乎是一种过于复杂的方式。那么，是否有更强大的方法来做到这一点？

#! /usr/bin/env python3

import subprocess
from gi.repository import Gio
import os
from time import sleep
import sys


def open_launcher(my_file):
    print('launcher open')
    app = subprocess.check_output(['xdg-mime', 'query', 'default', 'text/plain']).decode('utf-8').strip()
    print(app)
    launcher = Gio.DesktopAppInfo.new(app).get_commandline().split()[0]
    print(launcher)
    subprocess.call([launcher, my_file])
    print('launcher close')
    
def open_xdg(my_file):
    print('xdg open')
    subprocess.call(['xdg-open', my_file])
    print('xdg close')
    
def check_pid(pid):        
    """ Check For the existence of a unix pid. """
    try:
        os.kill(int(pid), 0)
    except OSError:
        return False
    else:
        return True
    
def open_pid(my_file):
    pid = subprocess.Popen(['xdg-open', my_file]).pid
    while check_pid(pid):
        print(pid)
        sleep(1)
        
def open_poll(my_file):
    proc = subprocess.Popen(['xdg-open', my_file])
    while not proc.poll():
        print(proc.poll())
        sleep(1)
        
def open_ps(my_file):
    subprocess.call(['xdg-open', my_file])
    pid = subprocess.check_output("ps -o pid,cmd -e | grep %s | head -n 1 | awk '{print $1}'" % my_file, shell=True).decode('utf-8')
    while check_pid(pid):
        print(pid)
        sleep(1)
        
def open_popen(my_file):
    print('popen open')
    process = subprocess.Popen(['xdg-open', my_file])
    process.wait()
    print(process.returncode)
    print('popen close')


# This will end the open_xdg function while the editor is open.
# However, if the editor is already open, open_launcher will finish while the editor is still open.
#open_launcher('test.txt')

# This solution opens the file but the process terminates before the editor is closed.
#open_xdg('test.txt')

# This will loop indefinately printing the pid even after closing the editor.
# If you check for the pid in another terminal you see the pid with: [xdg-open] <defunct>.
#open_pid('test.txt')

# This will print None once after which 0 is printed indefinately: the subprocess ends immediately.
#open_poll('test.txt')

# This seems to work, even when the editor is already open.
# However, I had to use head -n 1 to prevent returning multiple pids.
#open_ps('test.txt')

# Like open_xdg, this opens the file but the process terminates before the editor is closed.
open_popen('test.txt')

Answer 1

无需尝试轮询 PID，您可以使用 subprocess.Popen.wait() 简单地等待子进程终止。 :

Wait for child process to terminate. Set and return returncode attribute.

此外，获取 get_commandline() 的第一部分并不能保证是启动器。 get_commandline() 返回的字符串将匹配 the Exec key spec ，表示返回字符串中的%u、%U、%f和%F字段代码应该替换为正确的值。

下面是一些示例代码，基于您的xdg-mime 方法:

#!/usr/bin/env python3
import subprocess
import shlex
from gi.repository import Gio

my_file = 'test.txt'

# Get default application
app = subprocess.check_output(['xdg-mime', 'query', 'default', 'text/plain']).decode('utf-8').strip()

# Get command to run
command = Gio.DesktopAppInfo.new(app).get_commandline()

# Handle file paths with spaces by quoting the file path
my_file_quoted = "'" + my_file + "'"

# Replace field codes with the file path
# Also handle special case of the atom editor
command = command.replace('%u', my_file_quoted)\
    .replace('%U', my_file_quoted)\
    .replace('%f', my_file_quoted)\
    .replace('%F', my_file_quoted if app != 'atom.desktop' else '--wait ' + my_file_quoted)

# Run the default application, and wait for it to terminate
process = subprocess.Popen(
    shlex.split(command), stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
process.wait()

# Now the exit code of the text editor process is available as process.returncode

我对我的示例代码有一些评论。

备注1:处理文件路径中的空格

要打开的文件路径用引号引起来很重要，否则 shlex.split(command) 会用空格分割文件名。

备注 2:转义 % 个字符

Exec key spec州

Literal percentage characters must be escaped as %%.

我对 replace() 的使用可能会替换被转义的 % 字符。为简单起见，我选择忽略这种边缘情况。

备注3:原子

我假设期望的行为是一直等到图形编辑器关闭。在 atom 的情况下文本编辑器，它将在启动窗口时立即终止，除非提供了 --wait 选项。出于这个原因，如果默认编辑器是 atom，我有条件地添加 --wait 选项。

备注 4:subprocess.DEVNULL

subprocess.DEVNULL是 python 3.3 中的新功能。对于较旧的 python 版本，可以使用以下内容代替:

with open(os.devnull, 'w') as DEVNULL:
    process = subprocess.Popen(
        shlex.split(command), stdout=DEVNULL, stderr=DEVNULL)

测试

我在 GNOME 桌面环境的 Ubuntu 上测试了上面的示例代码。我使用以下图形文本编辑器进行了测试:gedit , mousepad , 和 atom .