yegle

Bash Shell启动方式与rc脚本

Shell的不同分类

根据启动Bash Shell的方式不同，对Shell有两种分类方式

登录Shell与非登录Shell

根据Shell的启动方式不同，可以将Shell分为

yegle

class API(app.page):
    pass


class DjangoAPI(API):
    model = None

    def __init__(self):
        self.qs = self.model.objects
        self.exclude = []

yegle

from itertools import product
import string

print(list(product(string.lowercase[:13],repeat=2)))

[('a', 'a'), ('a', 'b'), ('a', 'c'), ('a', 'd'), ('a', 'e'), ('a', 'f'), ('a', 'g'), ('a', 'h'), ('a', 'i'), ('a', 'j'), ('a', 'k'), ('a', 'l'), ('a', 'm'), ('b', 'a'), ('b', 'b'), ('b', 'c'), ('b', 'd'), ('b', 'e'), ('b', 'f'), ('b', 'g'), ('b', 'h'), ('b', 'i'), ('b', 'j'), ('b', 'k'), ('b', 'l'), ('b', 'm'), ('c', 'a'), ('c', 'b'), ('c', 'c'), ('c', 'd'), ('c', 'e'), ('c', 'f'), ('c', 'g'), ('c', 'h'), ('c', 'i'), ('c', 'j'), ('c', 'k'), ('c', 'l'), ('c', 'm'), ('d', 'a'), ('d', 'b'), ('d', 'c'), ('d', 'd'), ('d', 'e'), ('d', 'f'), ('d', 'g'), ('d', 'h'), ('d', 'i'), ('d', 'j'), ('d', 'k'), ('d', 'l'), ('d', 'm'), ('e', 'a'), ('e', 'b'), ('e', 'c'), ('e', 'd'), ('e', 'e'), ('e', 'f'), ('e', 'g'), ('e', 'h'), ('e', 'i'), ('e', 'j'), ('e', 'k'), ('e', 'l'), ('e', 'm'), ('f', 'a'), ('f', 'b'), ('f', 'c'), ('f', 'd'), ('f', 'e'), ('f', 'f'), ('f', 'g'), ('f', 'h'), ('f', 'i'), ('f', 'j'), ('f', 'k'), ('f', 'l'), 

yegle

#!/bin/bash

# FAIL!
echo a| read i
echo $i

# WORKS

read i <<<$(echo a)
echo $i

yegle

This is a brief introduction about how Linux kernel handles the send system call.

This study is based on kernel version 3.7.2, which is the latest stable kernel when writing this study.

How system call is defined

In the latest kernel, the system call is defined using the SYSCALL_DEFINEx macro, in which x is the number of arguments. For example, in order to find the definition of asmlinkage long sys_sendto(int, void __user *, size_t, unsigned, struct sockaddr __user *, int);, you need to grep for SYSCALL_DEFINE6 because it has 6 arguments.

The definition of the system call send can be found at net/socket.c.

yegle

    def get_readonly_fields(self, request, obj=None):
        if obj and obj.is_processed:
            return ('csv_file',) + self.readonly_fields
        else:
            return self.readonly_fields

yegle

#!/usr/bin/env python
# vim: set fileencoding=utf-8 ts=4 sw=4 tw=79 :

from __future__ import (unicode_literals, absolute_import,
                        division, print_function)

import requests
from lxml import etree
from io import StringIO

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import os
from google.appengine.ext import vendor

"""
1. Create a virtualenv directory at the root of your project, name it "venv"
2. Install packages needed in your project
3. Freeze it and save the package list into requirements.txt file, add it to
   version control
4. Exclude "venv" directory from version control
5. Save the content of this file as "appengine_config.py", and put it at the

yegle

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

class MyList(list):
    def __init__(self, raw_list, start=None, stop=None):
        self.raw_list = raw_list
        self.start = start or 0
        self.stop = stop or len(raw_list)-1

yegle

mkdir -p confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14B---/confdir-14