小编wan*_*020的帖子

我使用JSch来拖尾远程计算机中的文件.但我发现在程序退出后,"tail -f"进程仍然存在于远程计算机中.如果我删除"-f"参数,一切都OK.

我试过使用"sendSignal()",但它不起作用.似乎OpenSSH没有实现该功能.

这是测试代码.

public static void main(String[] args) throws Exception {
    String usr = args[0];
    String host = args[1];
    String password = args[2];
    JSch jsch = new JSch();
    Session session = jsch.getSession(usr, host);
    String pwd = password;
    session.setPassword(pwd);
    Hashtable<String, String> config = new Hashtable<String, String>();
    config.put("StrictHostKeyChecking", "no");
    session.setConfig(config);
    session.connect(15000);
    session.setServerAliveInterval(15000);


    ChannelExec m_channelExec = (ChannelExec) session.openChannel("exec");
    String cmd = "tail -f /var/log/messages";
    m_channelExec.setCommand(cmd);
    InputStream m_in = m_channelExec.getInputStream();
    m_channelExec.connect();
    BufferedReader m_bufferedReader = new BufferedReader(new InputStreamReader(m_in));
    int i = 0;
    while (++i …

我有2个DataFrames:

         city  count    school
0    New York      1  school_3
1  Washington      1  School_4
2  Washington      1  School_5
3          LA      1  School_1
4          LA      1  School_4

         city  count    school
0    New York      1  School_3
1  Washington      1  School_1
2          LA      1  School_3
3          LA      2  School_4

我想得到这个结果:

         city  count    school
0    New York      2  school_3
1  Washington      1  School_1
2  Washington      1  School_4
3  Washington      1  School_5
4          LA      1  School_1
5          LA      1  School_3
6          LA      3  School_4

以下是代码.

d1 …

有一个元组列表

l = [(1, 2, 'a', 'b'), (3, 4, 'c', 'd'), (5, 6, 'e', 'f')]

我可以用

[(i[0], i[2], i[3]) for i in l]

得到结果

[(1, 'a', 'b'), (3, 'c', 'd'), (5, 'e', 'f')]

但是如果给出一个变量列表[0, 2, 3],如何得到类似的结果呢？