当前位置:  互联网>综合

[1]python如何修改文件权限

网上能查到一些，但很多都没有讲清楚怎么获取stat里头的mode以及怎么只修改其中的一个位

做法如下：

import stat

  f_mode = os.stat(rndc_key_file).st_mode

  logging.info("stat mode of rndc key file:%o, after or:%o", stat.S_IMODE(f_mode), stat.S_IMODE(f_mode)|stat.S_IROTH)
  os.chmod(rndc_key_file, stat.S_IROTH|stat.S_IMODE(f_mode))

[2]Web服务器Tomcat ---- JDK环境变量设置DOS BAT批处理脚本 陈光剑

@echo off
rem Licensed to the Apache Software Foundation (ASF) under one or more
rem contributor license agreements.  See the NOTICE file distributed with
rem this work for additional information regarding copyright ownership.
rem The ASF licenses this file to You under the Apache License, Version 2.0
rem (the "License"); you may not use this file except in compliance with
rem the License.  You may obtain a copy of the License at
rem
rem     http://www.apache.org/licenses/LICENSE-2.0
rem
rem Unless required by applicable law or agreed to in writing, software
rem distributed under the License is distributed on an "AS IS" BASIS,
rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
rem See the License for the specific language governing permissions and
rem limitations under the License.


if "%OS%" == "Windows_NT" setlocal
rem ---------------------------------------------------------------------------
rem Start/Stop Script for the CATALINA Server
rem
rem Environment Variable Prerequisites
rem
rem   Do not set the variables in this script. Instead put them into a script
rem   setenv.bat in CATALINA_BASE/bin to keep your customizations separate.
rem
rem   CATALINA_HOME   May point at your Catalina "build" directory.
rem
rem   CATALINA_BASE   (Optional) Base directory for resolving dynamic portions
rem                   of a Catalina installation.  If not present, resolves to
rem                   the same directory that CATALINA_HOME points to.
rem
rem   CATALINA_OPTS   (Optional) Java runtime options used when the "start",
rem                   "run" or "debug" command is executed.
rem                   Include here and not in JAVA_OPTS all options, that should
rem                   only be used by Tomcat itself, not by the stop process,
rem                   the version command etc.
rem                   Examples are heap size, GC logging, JMX ports etc.
rem
rem   CATALINA_TMPDIR (Optional) Directory path location of temporary directory
rem                   the JVM should use (java.io.tmpdir).  Defaults to
rem                   %CATALINA_BASE%\temp.
rem
rem   JAVA_HOME       Must point at your Java Development Kit installation.
rem                   Required to run the with the "debug" argument.
rem
rem   JRE_HOME        Must point at your Java Runtime installation.
rem                   Defaults to JAVA_HOME if empty. If JRE_HOME and JAVA_HOME
rem                   are both set, JRE_HOME is used.
rem
rem   JAVA_OPTS       (Optional) Java runtime options used when any command
rem                   is executed.
rem                   Include here and not in CATALINA_OPTS all options, that
rem                   should be used by Tomcat and also by the stop process,
rem                   the version command etc.
rem                   Most options should go into CATALINA_OPTS.
rem
rem   JAVA_ENDORSED_DIRS (Optional) Lists of of semi-colon separated directories
rem                   containing some jars in order to allow replacement of APIs
rem                   created outside of the JCP (i.e. DOM and SAX from W3C).
rem                   It can also be used to update the XML parser implementation.
rem                   Defaults to $CATALINA_HOME/endorsed.
rem
rem   JPDA_TRANSPORT  (Optional) JPDA transport used when the "jpda start"
rem                   command is executed. The default is "dt_socket".
rem
rem   JPDA_ADDRESS    (Optional) Java runtime options used when the "jpda start"
rem                   command is executed. The default is 8000.
rem
rem   JPDA_SUSPEND    (Optional) Java runtime options used when the "jpda start"
rem                   command is executed. Specifies whether JVM should suspend
rem                   execution immediately after startup. Default is "n".
rem
rem   JPDA_OPTS       (Optional) Java runtime options used when the "jpda start"
rem                   command is executed. If used, JPDA_TRANSPORT, JPDA_ADDRESS,
rem                   and JPDA_SUSPEND are ignored. Thus, all required jpda
rem                   options MUST be specified. The default is:
rem
rem                   -agentlib:jdwp=transport=%JPDA_TRANSPORT%,
rem                       address=%JPDA_ADDRESS%,server=y,suspend=%JPDA_SUSPEND%
rem
rem   LOGGING_CONFIG  (Optional) Override Tomcat's logging config file
rem                   Example (all one line)
rem                   set LOGGING_CONFIG="-Djava.util.logging.config.file=%CATALINA_BASE%\conf\logging.properties"
rem
rem   LOGGING_MANAGER (Optional) Override Tomcat's logging manager
rem                   Example (all one line)
rem                   set LOGGING_MANAGER="-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
rem
rem   TITLE           (Optional) Specify the title of Tomcat window. The default
rem                   TITLE is Tomcat if it's not specified.
rem                   Example (all one line)
rem                   set TITLE=Tomcat.Cluster#1.Server#1 [%DATE% %TIME%]
rem
rem
rem
rem $Id: catalina.bat 1344732 2012-05-31 14:08:02Z kkolinko $
rem ---------------------------------------------------------------------------


rem Suppress Terminate batch job on CTRL+C
if not ""%1"" == ""run"" goto mainEntry
if "%TEMP%" == "" goto mainEntry
if exist "%TEMP%\%~nx0.run" goto mainEntry
echo Y>"%TEMP%\%~nx0.run"
if not exist "%TEMP%\%~nx0.run" goto mainEntry
echo Y>"%TEMP%\%~nx0.Y"
call "%~f0" %* <"%TEMP%\%~nx0.Y"
rem Use provided errorlevel
set RETVAL=%ERRORLEVEL%
del /Q "%TEMP%\%~nx0.Y" >NUL 2>&1
exit /B %RETVAL%
:mainEntry
del /Q "%TEMP%\%~nx0.run" >NUL 2>&1


rem Guess CATALINA_HOME if not defined
set "CURRENT_DIR=%cd%"
if not "%CATALINA_HOME%" == "" goto gotHome
set "CATALINA_HOME=%CURRENT_DIR%"
if exist "%CATALINA_HOME%\bin\catalina.bat" goto okHome
cd ..
set "CATALINA_HOME=%cd%"
cd "%CURRENT_DIR%"
:gotHome


if exist "%CATALINA_HOME%\bin\catalina.bat" goto okHome
echo The CATALINA_HOME environment variable is not defined correctly
echo This environment variable is needed to run this program
goto end
:okHome


rem Copy CATALINA_BASE from CATALINA_HOME if not defined
if not "%CATALINA_BASE%" == "" goto gotBase
set "CATALINA_BASE=%CATALINA_HOME%"
:gotBase


rem Ensure that any user defined CLASSPATH variables are not used on startup,
rem but allow them to be specified in setenv.bat, in rare case when it is needed.
set CLASSPATH=


rem Get standard environment variables
if not exist "%CATALINA_BASE%\bin\setenv.bat" goto checkSetenvHome
call "%CATALINA_BASE%\bin\setenv.bat"
goto setenvDone
:checkSetenvHome
if exist "%CATALINA_HOME%\bin\setenv.bat" call "%CATALINA_HOME%\bin\setenv.bat"
:setenvDone


rem Get standard Java environment variables
if exist "%CATALINA_HOME%\bin\setclasspath.bat" goto okSetclasspath
echo Cannot find "%CATALINA_HOME%\bin\setclasspath.bat"
echo This file is needed to run this program
goto end
:okSetclasspath
call "%CATALINA_HOME%\bin\setclasspath.bat" %1
if errorlevel 1 goto end


rem Add on extra jar file to CLASSPATH
rem Note that there are no quotes as we do not want to introduce random
rem quotes into the CLASSPATH
if "%CLASSPATH%" == "" goto emptyClasspath
set "CLASSPATH=%CLASSPATH%;"
:emptyClasspath
set "CLASSPATH=%CLASSPATH%%CATALINA_HOME%\bin\bootstrap.jar"


if not "%CATALINA_TMPDIR%" == "" goto gotTmpdir
set "CATALINA_TMPDIR=%CATALINA_BASE%\temp"
:gotTmpdir


rem Add tomcat-juli.jar to classpath
rem tomcat-juli.jar can be over-ridden per instance
if not exist "%CATALINA_BASE%\bin\tomcat-juli.jar" goto juliClasspathHome
set "CLASSPATH=%CLASSPATH%;%CATALINA_BASE%\bin\tomcat-juli.jar"
goto juliClasspathDone
:juliClasspathHome
set "CLASSPATH=%CLASSPATH%;%CATALINA_HOME%\bin\tomcat-juli.jar"
:juliClasspathDone


if not "%LOGGING_CONFIG%" == "" goto noJuliConfig
set LOGGING_CONFIG=-Dnop
if not exist "%CATALINA_BASE%\conf\logging.properties" goto noJuliConfig
set LOGGING_CONFIG=-Djava.util.logging.config.file="%CATALINA_BASE%\conf\logging.properties"
:noJuliConfig
set JAVA_OPTS=%JAVA_OPTS% %LOGGING_CONFIG%


if not "%LOGGING_MANAGER%" == "" goto noJuliManager
set LOGGING_MANAGER=-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
:noJuliManager
set JAVA_OPTS=%JAVA_OPTS% %LOGGING_MANAGER%


rem ----- Execute The Requested Command ---------------------------------------


echo Using CATALINA_BASE:   "%CATALINA_BASE%"
echo Using CATALINA_HOME:   "%CATALINA_HOME%"
echo Using CATALINA_TMPDIR: "%CATALINA_TMPDIR%"
if ""%1"" == ""debug"" goto use_jdk
echo Using JRE_HOME:        "%JRE_HOME%"
goto java_dir_displayed
:use_jdk
echo Using JAVA_HOME:       "%JAVA_HOME%"
:java_dir_displayed
echo Using CLASSPATH:       "%CLASSPATH%"


set _EXECJAVA=%_RUNJAVA%
set MAINCLASS=org.apache.catalina.startup.Bootstrap
set ACTION=start
set SECURITY_POLICY_FILE=
set DEBUG_OPTS=
set JPDA=


if not ""%1"" == ""jpda"" goto noJpda
set JPDA=jpda
if not "%JPDA_TRANSPORT%" == "" goto gotJpdaTransport
set JPDA_TRANSPORT=dt_socket
:gotJpdaTransport
if not "%JPDA_ADDRESS%" == "" goto gotJpdaAddress
set JPDA_ADDRESS=8000
:gotJpdaAddress
if not "%JPDA_SUSPEND%" == "" goto gotJpdaSuspend
set JPDA_SUSPEND=n
:gotJpdaSuspend
if not &qu      

      
      
    

      

[3]搭建一个后台服务器--引子

最近去了几家公司面试，有一些大公司（比如企鹅）的考核内容真心弱智，考的都是些算法，尼玛，拿一个刚毕业的学生来做说不定也可以过的，看来本来就不是在招搞服务器的，举个例子，企鹅多个部门都曾出的一道题：如何知道集合A,B中的相关性。

意思就是哪些元素在A,B之中都有，哪些元素在A,B中不都出现。

其实解法很简单，学过算法的完全可以做到 。我们知道集合具有互异性，就是集合中的元素只能出现一次，可以建一个map< key, value >，是标准库的还是自建一个红黑树都无所谓，

将A,B集合中的元素当成key,各自遍历一次，插入map中，每次插入 value自增一次，最后再遍历一次map，所有 value = 2的key是A,B共有的，value=1的key是A,B相异的。

如果A,B中的元素是整数，而且很小，问题则退化成类似计数排序，解法如下：

#define MAX_NUM

A{ 2,4,6,10,7,25 } B{ 3,9,4,2,19,25 }

int test( int A[], int a_len, int B[], int b_len )

{

int size, i, max, tp_key;

int  *tmp;

if( !a_len || !b_len )

{

return -1;

}

size = MAX_NUM * sizeof( int );

tmp = malloc( size );

if( !tmp )

{

return -1;

}

memset( tmp, 0, size );

max = 0;

for( i = 0; i < a_len; ++i )

{

tp_key = A[i];

max = tp_key > max ? tp_key : max;

tmp[ tp_key ]++;

}

for( i = 0; i < b_len; ++i )

{

tp_key = B[i];

max = tp_key > max ? tp_key : max;

tmp[ tp_key ] ++;

}

++max;

for( i = 0; i < max; ++i )

{

if( !tmp[ i ] )

continue;

if( 1 == tmp[ i ]  )

{

printf( "%d is in A or B\n", i );

}

else

{

printf( "%d is in A and B\n", i );

}

}

free( tmp );

return 0;

}

言归正传，其实算法应该是大家的基本功，考核算法应该也没有错，但既然招的是服务器架构开发，我想考核更多的是实战经验。

有一家中等公司的面试题不错，此系列博文将围绕它展开研究。

原题：时间同步系统开发需求

需求场景：客户端向服务器发起登录请求，鉴权通过后（为了简化工作，所有登录请求，只要请求参数里的用户名和密码不为空，都鉴权通过），客户端再向服务器请求当前系统时间，服务器返回当前系统时间后关闭连接。

要求：

1、传输层使用TCP协议，应用层协议不限。

2、可支持同时在线用户量：大于 2W。

3、并发性能：没有明确指标。

4、服务器端运行环境：linux 2.4以上内核版本；开发语言：C++/C。

5、客户端运行环境：不限；开发语言：不限。（可以很简单，不要求界面）

6、要求有模拟性能测试操作方法，如多客户端、多线程模拟同时请求等。

7、用真实代码。

8、不要求日志系统，但是要考虑在主线程打印屏幕引起的性能问题。

我就觉得要是哪个公司面试的时候能出得出这样的题目，那就应该很专业了，对面试的人也就可以算得上挑战了。

tcp 服务端-客户端通信的程序，网上一搜一大堆，大家可能都会写，但是并发量和容错性不一定能上得去，2W的并发量不是盖出来的，如果这道题目能够搞定，基本上服务器这块应该是难不倒了。

下面说说我应该怎么做：

首先是建立前后端的通信协议：

request:

username/password, 约定username与password  各占32个字节（联同末位0)

response:

time_t 格式

由于通信内容简单，选择二进制传输，而不选择http，当然如果要考考 http 协议的了解，那就另当别论了。

不忙写程序，再对题目好好看看，因为我打算连载，请关注啦，呵呵。

下篇我给大家写客户端程序先。