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#235 shar: Shell Archive

Linux b2a 2018-02-02

sudo apt install sharutils

提供四个命令：

shar: create a shell archive
unshar: unpack a shar archive
uudecode: decode an encoded file
uuencode: encode a file into email friendly text

uuencode 是一种二进制转文本编码，类似 Base64

没想到还有些包依赖这个上世纪遗留下来的编码（包括 gcc）：

apt rdepends sharutils
sharutils
Reverse Depends:
  建议: file-roller
  依赖: wide-dhcpv6-client
  推荐: speechd-el
  建议: patool
  推荐: mgp
  建议: lxqt-archiver
  推荐: ldapscripts
  依赖: kpatch-build
  依赖: knews
  建议: git-dpm
  依赖: gcc-9-source
  依赖: gcc-12-source
  依赖: gcc-11-source
  依赖: gcc-10-source
  建议: engrampa
  依赖: biabam
  推荐: aespipe

python uuencode

import uu

uu.encode('/etc/passwd', '-')

注意：3.11 开始，python Deprecated 了这个 uu 模块, 可以改用 binascii.b2a_uu 代替。

import binascii

s = b''
with open('/etc/passwd', 'rb') as f:
    buf = f.read(45)
    while len(buf) > 0:
        s += binascii.b2a_uu(buf, backtick=False)
        buf = f.read(45)
print(s)

#234 Python 项目结构图

Python Pyreverse UML graphviz dot 2018-01-30

常用的代码风格检查工具 pylint 中集成了 pyreverse, 这是一个用于生成 Python 的类图的工具。

#233 DOT 语言与 Graphviz 工具 [编辑中]

graphviz dot 2018-01-30

:) 本文正在编辑中，暂时不提供浏览...

#232 CSS Reset

CSS 2018-01-27

由于浏览器实现上的差异，导致相同的页面在不同浏览器下的呈现不同，甚至会有错乱。
所以，一般前端框架会使用一个重置样式打底，以确保不同浏览器下的显示效果统一。

reset.css 对所有组件的默认样式进行统一定义
An unmodified copy of Eric Meyer's CSS reset.
https://www.npmjs.com/package/reset-css
normalize.css 针对部分样式进行修补
https://www.npmjs.com/package/normalize-css

参考资料与拓展阅读

html {
  max-width: 70ch;
  padding: 3em 1em;
  margin: auto;
  line-height: 1.75;
  font-size: 1.25em;
}

Let’s break this down. I’ve adapted the original text with my own commentary.

max-width: 70ch: the “readable range” is usually 60-80 character widths, and CSS lets you express that directly with the ch unit. I blogged more on line lengths last year.
padding: 3em 1em: If the display’s width goes under the max-width set above, then this padding prevents edge-to-edge text on mobile. We use 3em to provide top/bottom whitespace.
margin: auto: This is really all that is needed to center the page - applied on html, because Dan’s site doesnt have a semantic <main> tag and <html> is more likely to exist in most sites (no judgment pls, i’ve heard enough semantic HTML preaching). That the top tag centers itself relative to nothing is unintuitive, but thats how browsers do.
line-height: 1.75: Spacing between the lines to help increase visual clarity. Always leave line height unitless because reasons.
font-size: 1.5em: I’ve noticed that recent design trends and screen sizes have tended toward bigger font sizes. Or maybe I’m getting old. Prefer em or rem over px if you want to let users scale it.

Tushar points out that you can use :root instead of <html> to guarantee that there is some selector present, but its a touch too fancy for me and uses an extra character :)

Optional:

h1,
h2,
h3,
h4,
h5,
h6 {
  margin: 3em 0 1em;
}

p,
ul,
ol {
  margin-bottom: 2em;
  color: #1d1d1d;
  font-family: sans-serif;
}

Being Picky about a CSS Reset for Fun & Pleasure
著名 CSS 作者 Chris Coyier 的最新文章，解释浏览器的 CSS 重置（CSS reset）每一行的意思。

#231 Windows 开机启动

Windows 2018-01-26

我想开机启动 TIM，但是 TIM 的设置没有用，重启之后这个选项又自己取消了，只好另外寻找方法。
发现这个方法就挺好用，只需把应用程序的快捷方式复制到一个目录。

这三个方法都可以用资源管理器打开这个目录：

win + r 然后 shell:startup 回车
explorer %appdata%\Microsoft\Windows\Start Menu\Programs\Startup
explorer %userprofile%\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup

物理结构

机械硬盘 Disk -> 盘片/盘面 Platter -> 磁道 Tracker -> 扇区 Physical Sector
光盘
SSD -> NAND Package -> Die -> Plane -> Block -> Page
非易失性存储器（永久）：NAND Flash
易失性存储器（临时）：DRAM

扇区大小是厂商定的，一般是 512B 的倍数。
老的机械硬盘一般是 512B 扇区，新的机械硬盘一般是 4K 扇区（AF，Advanced Format）
光盘（CD/DVD）一般是 2K 扇区。

处于向前兼容的目的，其他类型存储设备的大小也一般是 512B。

逻辑结构

逻辑扇区 Logical Sector
块 Block
Windows 下叫做簇 Cluster，或者磁盘分配单元。
PS：内存上的类似概念，是段 Segment 和页 Page

$ sudo fdisk /dev/sda -l
Disk /dev/sda: 40 GiB, 42949672960 bytes, 83886080 sectors
Disk model: VBOX HARDDISK
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 7EC7FA37-FE79-46C1-A404-56AA0E00CFAB

Device       Start      End  Sectors Size Type
/dev/sda1     2048     4095     2048   1M BIOS boot
/dev/sda2     4096  4198399  4194304   2G Linux filesystem
/dev/sda3  4198400 83884031 79685632  38G Linux filesystem

格式化

https://zh.wikipedia.org/wiki/磁盘格式化

低级格式化、物理格式化

对于部分硬盘制造厂商，它也被称为初始化。
最早，低级格式化被用于指代对磁盘进行划分柱面、磁道、扇区的操作。
现今，随着软盘的逐渐退出日常应用，应用新的编址方法和接口的磁盘的出现，这个词已经失去了原本的含义，大多数的硬盘制造商将低级格式化定义为创建硬盘扇区（sector）使硬盘具备存储能力的操作。现在，人们对低级格式化存在一定的误解，多数情况下，提及低级格式化，往往是指硬盘的填零操作。

高级格式化、逻辑格式化
根据用户选定的文件系统，在磁盘的特定区域写入特定数据，以达到初始化磁盘或磁盘分区、清除原磁盘或磁盘分区中所有文件的一个操作。
高级格式化包括对主引导记录中分区表相应区域的重写、根据用户选定的文件系统，在分区中划出一片用于存放文件分配表、目录表等用于文件管理的磁盘空间，以便用户使用该分区管理文件。

常见文件系统类型

FAT / FAT32 / exFAT
NTFS
EXT2 / EXT3 / EXT4
BTRFS
Apple HFS

参考资料与拓展阅读

知乎专栏，拆解固态硬盘结构
Seagate，过渡到高级格式化 4K 扇区硬盘

#229 Python 多进程共同监听同一个端口

Python 网络编程 2018-01-23

import socket
import signal
import sys
import os

def handle_connection(conn):
    conn.close()

def worker(sock):
    while True:
        try:
            conn, addr = sock.accept()
            handle_connection(conn)
        except OSError as e:
            if e.errno == socket.ECONNABORTED:
                # 忽略 ECONNABORTED 错误
                pass
            else:
                raise

def main():
    port = 8080
    backlog = 10  # 连接队列长度（超出会拒绝或忽略）
    num_workers = 4 # 子进程数

    # 创建监听器
    listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    listener.bind(('localhost', port))
    listener.listen(backlog)
    sock.setblocking(False)
    print(f"Listening on port {port}...")

    # # “来一个连接，起一个进程”的模式
    # def sig_handler(sig, frame):
    #     listener.close()
    #     sys.exit(0)
    # signal.signal(signal.SIGINT, sig_handler)
    # signal.signal(signal.SIGTERM, sig_handler)
    # while True:
    #     conn, addr = listener.accept()
    #     pid = os.fork()
    #     if pid == 0:
    #         listener.close()
    #         handle_connection(conn)
    #         sys.exit(0)
    #     else:
    #         conn.close()

    # 子进程放到进程组中
    os.setpgrp()

    # 多个 worker 子进程一同监听端口的模式
    processes = []
    for i in range(num_workers):
        p = Process(target=worker, args=(sock,))
        processes.append(p)
        p.start()
    # 通过 os.killpg 向进程组发送信号
    signal.signal(signal.SIGINT, lambda signum, frame: os.killpg(0, signal.SIGINT))
    signal.signal(signal.SIGTERM, lambda signum, frame: os.killpg(0, signal.SIGTERM))
    signal.pause()
    for p in processes:
        p.terminate()

if __name__ == '__main__':
    main()

惊群效应是指事件发生的时候，多个进程或线程竞争处理这个事件，导致系统负载出现一个尖峰。严重的情况下可能导致系统瘫痪。
虽然 accept 会阻塞住，只有一个抢到，但是惊群的问题应该还是存在。

进程组

os.setpgrp 设置进程组
os.killpg 向进程组发送信号，如果没有设置进程组，这个操作没有意义
os.set_inheritable 继承文件描述符，然后可以独立使用和关闭

内存分配

堆内存 heap
垃圾回收：
引用计数
延迟回收（支持手动触发）

引用计数

标记清除

标记所有当前正在使用的对象，然后清除所有未被标记的对象来回收内存。
这个算法的缺点是当内存中有大量未被标记的垃圾时，清除过程可能会变得非常缓慢。

分代回收

将对象分为三代：

新创建的对象放在第 0 代
第 1 代包含一些活跃的对象
第 2 代包含一些非常稳定的对象

不同代执行不同的标记策略。

Active Directory

ADmodcmd Active Directory Bulk Modify
CSVDE Import or Export Active Directory data
DSACLs Active Directory ACLs
DSAdd Add items to active directory (user group computer)
DSGet View items in active directory (user group computer)
DSQuery Search for items in active directory (user group computer)
DSMod Modify items in active directory (user group computer)
DSMove Move an Active directory Object
DSRM Remove items from Active Directory

Batch Files

CALL Call one batch program from another 内部命令
CHOICE Accept keyboard input to a batch file
CLIP Copy STDIN to the Windows clipboard
CLS Clear the screen 内部命令
CMD Start a new CMD shell
COLOR Change colors of the CMD window 内部命令
DOSKEY Edit command line, recall commands, and create macros
ECHO Display message on screen 内部命令
ENDLOCAL End localisation of environment changes in a batch file 内部命令
EVENTCREATE Add a message to the Windows event log
EXIT Quit the current script/routine and set an errorlevel 内部命令
FOR /F Loop command: against a set of files 内部命令
FOR /F Loop command: against the results of another command 内部命令
FOR Loop command: all options Files, Directory, List 内部命令
GOTO Direct a batch program to jump to a labelled line 内部命令
IF Conditionally perform a command 内部命令
IFMEMBER Is the current user a member of a Workgroup
LOGTIME Log the date and time in a file
MAPISEND Send email from the command line
MORE Display output, one screen at a time
PAUSE Suspend processing of a batch file and display a message 内部命令
PROMPT Change the command prompt 内部命令
REM Record comments (remarks) in a batch file 内部命令
RUN Start | RUN commands
RUNAS Execute a program under a different user account
SET Display, set, or remove session environment variables 内部命令
SETLOCAL Control the visibility of environment variables 内部命令
SETX Set environment variables
SORT Sort input
SHIFT Shift the position of batch file parameters 内部命令
SLEEP Wait for x seconds
START Start a program, command or batch file 内部命令
TIMEOUT Delay processing of a batch file
TITLE Set the window title for a CMD.EXE session 内部命令
WAITFOR Wait for or send a signal
WMIC WMI Commands
:: Comment / Remark 内部命令

Disk Management

BCDBOOT Create or repair a system partition
BCDEDIT Manage Boot Configuration Data
CONVERT Convert a FAT drive to NTFS
CHKDSK Check Disk - check and repair disk problems
CHKNTFS Check the NTFS file system
DEFRAG Defragment hard drive
DISKPART Disk Administration
DISKSHADOW Volume Shadow Copy Service
DriverQuery Display installed device drivers
FORMAT Format a disk
FREEDISK Check free disk space (in bytes)
LABEL Edit a disk label
MOUNTVOL Manage a volume mount point
NTBACKUP Backup folders to tape
SFC System File Checker
VOL Display a disk label 内部命令

Files and Folders

ASSOC Change file extension associations 内部命令
ASSOCIAT One step file association
ATTRIB Change file attributes
BITSADMIN Background Intelligent Transfer Service
CACLS Change file permissions
CD Change Directory - move to a specific Folder 内部命令
CIPHER Encrypt or Decrypt files/folders
COMP Compare the contents of two files or sets of files
COMPACT Compress files or folders on an NTFS partition
COMPRESS Compress individual files on an NTFS partition
COPY Copy one or more files to another location 内部命令
CSCcmd Client-side caching (Offline Files)
DEL Delete one or more files 内部命令
DELTREE Delete a folder and all subfolders
DIR Display a list of files and folders 内部命令
ERASE Delete one or more files 内部命令
EXPAND Uncompress files
EXTRACT Uncompress CAB files
FC Compare two files
FIND Search for a text string in a file
FINDSTR Search for strings in files
FORFILES Batch process multiple files
FSUTIL File and Volume utilities
FTP File Transfer Protocol
FTYPE File extension file type associations 内部命令
iCACLS Change file and folder permissions
MD Create new folders 内部命令
MOVE Move files from one folder to another 内部命令
MKLINK Create a symbolic link (linkd)
OPENFILES Query or display open files
POPD Return to a previous directory saved by PUSHD 内部命令
PsFile Show files opened remotely
PUSHD Save and then change the current directory 内部命令
RECOVER Recover a damaged file from a defective disk
REN Rename a file or files 内部命令
REPLACE Replace or update one file with another
RD Delete folder(s) 内部命令
RMTSHARE Share a folder or a printer
ROBOCOPY Robust File and Folder Copy
SHARE List or edit a file share or print share
SHORTCUT Create a windows shortcut (.LNK file)
SUBINACL Edit file and folder Permissions, Ownership and Domain
TAKEOWN Take ownership of a file
TOUCH Change file timestamps
TREE Graphical display of folder structure
TYPE Display the contents of a text file 内部命令
WHERE Locate and display files in a directory tree
WINDIFF Compare the contents of two files or sets of files
XCACLS Change file and folder permissions
XCOPY Copy files and folders

Group Policy/Windows Installer

DevCon Device Manager Command Line Utility
GPRESULT Display Resultant Set of Policy information
GPUPDATE Update Group Policy settings
MSIEXEC Microsoft Windows Installer
PsInfo List information about a system
PsShutdown Shutdown or reboot a computer
REGSVR32 Register or unregister a DLL
SHUTDOWN Shutdown the computer
SLMGR Software Licensing Management (Vista/2008)
WUAUCLT Windows Update

Networking

ARP Address Resolution Protocol
BROWSTAT Get domain, browser and PDC info
DNSSTAT DNS Statistics
GETMAC Display the Media Access Control (MAC) address
IPCONFIG Configure IP
NET Manage network resources
NETDOM Domain Manager
NETSH Configure Network Interfaces, Windows Firewall & Remote access
NBTSTAT Display networking statistics (NetBIOS over TCP/IP)
NETSTAT Display networking statistics (TCP/IP)
NMBIND Manage Hyper-V network bindings
NSLOOKUP Name server lookup
PATHPING Trace route plus network latency and packet loss
PsPing Measure network performance
PING Test a network connection
ROUTE Manipulate network routing tables
TRACERT Trace route to a remote host

Processes

PATH Display or set a search path for executable files 内部命令
PsExec Execute process remotely
PsKill Kill processes by name or process ID
PsList List detailed information about processes
PsGetSid Display the SID of a computer or a user
PsSuspend Suspend processes
SCHTASKS Schedule a command to run at a specific time
SYSMON Monitor and log system activity to the Windows event log
TASKLIST List running applications and services
TASKKILL End a running process
TSKILL End a running process
TLIST Task list with full path

Printing

MODE Configure a system device
PRINT Print a text file
PRINTBRM Print queue Backup/Recovery
RUNDLL32 Run a DLL command (add/remove print connections)

Recovery

BOOTREC Repair or replace a partition boot sector (WinRE).
BCDBOOT Create or repair a system partition.
BCDEDIT Manage Boot Configuration Data.
WPEUTIL Run commands during a Windows Preinstallation Environment (WinPE) session.

Registry

REG Registry: Read, Set, Export, Delete keys and values
REGEDIT Import or export registry settings
REGINI Change Registry Permissions

Remote Desktop

CHANGE Change Terminal Server Session properties
Query Process Display processes (TS/Remote Desktop)
Query Session Display all sessions (TS/Remote Desktop)
Query TermServer List all servers (TS/Remote Desktop)
Query User Display user sessions (TS/Remote Desktop)
MSTSC Terminal Server Connection (Remote Desktop Protocol)
RASDIAL Manage RAS connections
RASPHONE Manage RAS connections
Reset Session Delete a Remote Desktop Session
TSDISCON Disconnect a Remote Desktop Session
WINRM Windows Remote Management
WINRS Windows Remote Shell

Services

CASPOL Code Access Security Policy Tool.
PORTQRY Display the status of ports and services
PsService View and control services
SC Service Control

System Information

CHANGEPK Upgrade device Edition/Product Key
DATE Display or set the date 内部命令
HELP Online Help
LOGMAN Manage Performance Monitor logs
MBSAcli Baseline Security Analyzer
MSINFO32 System Information
NOW Display the current Date and Time
NTRIGHTS Edit user account rights
PsLogList Event log records
SFC System File Checker
SXSTRACE Diagnose side-by-side problems.
SYSMON Monitor and log system activity to the Windows event log
SYSTEMINFO List system configuration
TIME Display or set the system time 内部命令
TypePerf Write performance data to a log file
VER Display version information 内部命令
VERIFY Verify that files have been saved 内部命令
WHOAMI Output the current UserName and domain

User Administration

ADDUSERS Add or list users to/from a CSV file
CERTREQ Request certificate from a certification authority
CleanMgr Automated cleanup of Temp files, recycle bin
CON2PRT Connect or disconnect a Printer
CMDKEY Manage stored usernames/passwords
DELPROF Delete user profiles
DIRUSE Display disk usage
LOGOFF Log a user off
MOVEUSER Move a user from one domain to another
MSG Send a message
PERMS Show permissions for a user
POWERCFG Configure power settings
PsLoggedOn Who's logged on (locally or via resource sharing)
PsPasswd Change account password
SUBST Associate a path with a drive letter

Commands marked • are Internal commands only available within the CMD shell.
All other commands (not marked with •) are external commands.
External commands may be used under the CMD shell, PowerShell, or directly from START-RUN.

参考资料与拓展阅读

#226 Bash set 命令

Bash Linux 命令行 2018-01-11

我写 Shell 脚本一般都是用 bash 执行，一般我会在头部插入 set -xue 命令, 助记：蛇血。

那么这个命令的作用是什么呢？

set 是 bash 提供的一个命令，用来管理 bash 的一些行为。

x: 在执行命令前，输出所有命令，包括参数。
u: 遇到未定义变量时，报错。
e: 如果遇到错误，程序退出。

其他更多参数，参考：set --help 或 help set。

码厩技术博客

#235 shar: Shell Archive

python uuencode

#234 Python 项目结构图

#233 DOT 语言与 Graphviz 工具 [编辑中]

:) 本文正在编辑中，暂时不提供浏览...

#232 CSS Reset

参考资料与拓展阅读

#231 Windows 开机启动

#230 Linux 文件系统

物理结构

逻辑结构

格式化

常见文件系统类型

参考资料与拓展阅读

#229 Python 多进程共同监听同一个端口

进程组

#228 Python 内存管理

内存分配

引用计数

相关工具

#227 Windows 命令大全

Active Directory

Batch Files

Disk Management

Files and Folders

Group Policy/Windows Installer

Networking

Processes

Printing

Recovery

Registry

Remote Desktop

Services

System Information

User Administration

参考资料与拓展阅读

#226 Bash set 命令

一	二	三	四	五	六	日