#命令模式下输入:光标移动到第34行第15个字符
15l(这是小写的L)

ctrl+u删除光标前面的字符

ctrl+j删除光标后面的字符

在Linux下用VIM打开大小几个G、甚至几十个G的文件时，是非常慢的。

这时，我们可以利用下面的方法分割文件，然后再打开。

1 查看文件的前多少行

head -10000 /var/lib/mysql/slowquery.log > temp.log

上面命令的意思是：把slowquery.log文件前10000行的数据写入到temp.log文件中。

2 查看文件的后多少行

tail -10000 /var/lib/mysql/slowquery.log > temp.log

上面命令的意思是：把slowquery.log文件后10000行的数据写入到temp.log文件中。

3 查看文件的几行到几行

sed -n '10,10000p' /var/lib/mysql/slowquery.log > temp.log

上面命令的意思是：把slowquery.log文件第10到10000行的数据写入到temp.log文件中。

acmer之ubuntu下安装Eclipse（附有CB16.01的安装和chrome的安装）

发现孤儿进程的ppid并不等于1，是967，这个967是桌面的祖先进程

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1. 管道（pipe）,流管道(s_pipe)和有名管道（FIFO）

2. 信号（signal）

3. 消息队列

4. 共享内存

5. 信号量

6. 套接字（socket)

线程同步互斥的4种方式

1.  临界区（Critical Section）：适合一个进程内的多线程访问公共区域或代码段时使用

2.  互斥量 (Mutex)：适合不同进程内多线程访问公共区域或代码段时使用，与临界区相似。

3.  事件（Event）：通过线程间触发事件实现同步互斥

4.  信号量（Semaphore）：与临界区和互斥量不同，可以实现多个线程同时访问公共区域数据，原理与操作系统中PV操作类似，先设置一个访问公共区域的线程最大连接数，每有一个线程访问共享区资源数就减一，直到资源数小于等于零。

ctrl+alt+F1进入字符界面,再次运行刚才程序,出现了结果,ppid=1.

ctrl+alt+F7进入图形界面，就可以继续愉快的图形界面了

pwd:print work directory 打印当前目录 显示出当前工作目录的绝对路径

ps: process status(进程状态，类似于windows的任务管理器)

netstat -s命令

[root@server ~]# netstat -s | egrep "listen|LISTEN" 667399 times the listen queue of a socket overflowed 667399 SYNs to LISTEN sockets ignored
比如上面看到的 667399 times ，表示全连接队列溢出的次数，隔几秒钟执行下，如果这个数字一直在增加的话肯定全连接队列偶尔满了。
[root@server ~]# netstat -s | grep TCPBacklogDrop 查看 Accept queue 是否有溢出

ss命令

[root@server ~]# ss -lnt State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 :6379 : LISTEN 0 128 :22 : 如果State是listen状态，Send-Q 表示第三列的listen端口上的全连接队列最大为50，第一列Recv-Q为全连接队列当前使用了多少。 非 LISTEN 状态中 Recv-Q 表示 receive queue 中的 bytes 数量；Send-Q 表示 send queue 中的 bytes 数值。

十个提高效率的命令别名

#解压
alias untar='tar -zxvf '
#支持断点下载
alias wget='wget -c '
#生成一个 个字符的随机数密码
alias getpass="openssl rand -base64 20"
#校验checksum
alias sha='shasum -a 256 '
#正常下无数次，可以设置一个合理次数
alias ping='ping -c 5'
#启动web服务器进行测试
alias www='python -m SimpleHTTPServer 8000'
#网速测试，需要下载
alias speed='speedtest-cli --server 2406 --simple'
#查看公网IP
alias ipe='curl ipinfo.io/ip'
#查看局域网IP
alias ipi='ipconfig getifaddr en0'
#清屏，可以ctrl+L，
alias cls='clear'

常用参数：－auxf

ps -auxf 显示进程状态

df: disk free 其功能是显示磁盘可用空间数目信息及空间结点信息。换句话说，就是报告在任何安装的设备或目录中，还剩多少自由的空间。

du: Disk usage

rpm：即RedHat Package Management，是RedHat的发明之一

rmdir：Remove Directory（删除目录）

rm：Remove（删除目录或文件）

cat: concatenate 连锁

cat file1file2>>file3 把文件1和文件2的内容联合起来放到file3中

insmod: install module,载入模块

ln -s : link -soft 创建一个软链接，相当于创建一个快捷方式

mkdir：Make Directory(创建目录)

touch

man: Manual

su：Swith user(切换用户)

cd：Change directory

ls：List files

ps：Process Status

mkdir：Make directory

rmdir：Remove directory

mkfs: Make file system

fsck：File system check

uname: Unix name

lsmod: List modules

mv: Move file

rm: Remove file

cp: Copy file

ln: Link files

fg: Foreground

bg: Background

chown: Change owner

chgrp: Change group

chmod: Change mode

umount: Unmount

dd: 本来应根据其功能描述“Convert an copy”命名为“cc”，但“cc”已经被用以代表“CComplier”，所以命名为“dd”

tar：Tape archive （磁带档案）

ldd：List dynamic dependencies

insmod：Install module

rmmod：Remove module

lsmod：List module

文件结尾的"rc"（如.bashrc、.xinitrc等）：Resource configuration

Knnxxx /Snnxxx（位于rcx.d目录下）：K（Kill）；S(Service)；

nn（执行顺序号）；xxx（服务标识）

.a（扩展名a）：Archive，static library

.so（扩展名so）：Shared object，dynamically linked library

.o（扩展名o）：Object file，complied result of C/C++ source file

RPM：Red hat package manager

dpkg：Debian package manager

apt：Advanced package tool（Debian或基于Debian的发行版中提供）

部分Linux命令缩写

bin = Binaries (二进制文件)

/dev = Devices (设备)

/etc = Etcetera (等等)

/lib = LIBrary

/proc = Processess

/sbin = Superuser Binaries (超级用户的二进制文件)

/tmp = Temporary (临时)

/usr = Unix Shared Resources

/var = Variable (变量)

FIFO = First In, First Out

GRUB = GRand Unified Bootloader

IFS= Internal Field Seperators

LILO = LInux LOader

MySQL = My 是最初作者女儿的名字，

SQL = Structured QueryLanguage

PHP = Personal Home Page Tools = PHP HypertextPreprocessor

PS = Prompt String

Perl = "Pratical Extraction and Report Language"(实际的抽取和报告语言) ="Pathologically Eclectic Rubbish Lister"

Python 得名于电视剧Monty Python's Flying Circus

Tcl = Tool Command Language

Tk = ToolKit

VT = Video Terminal

YaST = Yet Another Setup Tool

apache = "a patchy" server

apt = Advanced Packaging Tool

ar = archiver

as = assembler

awk = "Aho Weiberger and Kernighan"三个作者的姓的第一个字母

bash = Bourne Again SHell

bc = Basic (Better) Calculator

bg = BackGround

biff = 作者HeidiStettner在U.C.Berkely养的一条狗,喜欢对邮递员汪汪叫。

cal = Calendar (日历)

cat = Catenate (链接)

cd = Change Directory

chgrp = Change Group

chmod = Change Mode

chown = Change Owner

chsh = Change Shell

cmp = compare

cobra = Common Object Request BrokerArchitecture

comm = common

cp = Copy

cpio = CoPy In and Out

cpp = C Pre Processor

cron = Chronos 希腊文时间

cups = Common Unix Printing System

cvs = Current Version System

daemon = Disk And Execution MONitor

dc = Desk Calculator

dd = Disk Dump (磁盘转储)

df = Disk Free

diff = Difference

dmesg = diagnostic message

du = Disk Usage

ed = editor

egrep = Extended GREP

elf = Extensible Linking Format

elm = ELectronic Mail

emacs = Editor MACroS

eval = EVALuate

ex = EXtended

exec = EXECute (执行)

fd = file descriptors

fg = ForeGround

fgrep = Fixed GREP

fmt = format

fsck = File System ChecK

fstab = FileSystem TABle

fvwm = F*** Virtual Window Manager

gawk = GNU AWK

gpg = GNU Privacy Guard

groff = GNU troff

hal = Hardware Abstraction Layer

joe = Joe's Own Editor

ksh = Korn SHell

lame = Lame Ain't an MP3 Encoder

lex = LEXical analyser

lisp = LISt Processing = Lots of IrritatingSuperfluous Parentheses

ln = Link

lpr = Line PRint

ls = list

lsof = LiSt Open Files

m4 = Macro processor Version 4

man = MANual pages

mawk = Mike Brennan's AWK

mc = Midnight Commander

mkfs = MaKe FileSystem

mknod = Make Node

motd = Message of The Day

mozilla = MOsaic GodZILLa

mtab = Mount TABle

mv = Move

nano = Nano's ANOther editor

nawk = New AWK

nl = Number of Lines

nm = names

nohup = No HangUP

nroff = New ROFF

od = Octal Dump

passwd = Passwd

pg = pager

pico = PIne's message COmposition editor

pine = "Program for Internet News &Email" = "Pine is not Elm"

ping = 拟声 又 = Packet Internet Grouper

pirntcap = PRINTer CAPability

popd = POP Directory

pr = pre

printf = Print Formatted

ps = Processes Status

pty = pseudo tty

pushd = PUSH Directory

pwd = Print Working Directory

rc = runcom = run command, rc还是plan9的shell

rev = REVerse

rm = ReMove

rn = Read News

roff = RunOFF

rpm = RPM Package Manager = RedHat PackageManager

rsh, rlogin, rvim中的

r = Remote

rxvt = ouR XVT

seamoneky = 我

sed = Stream Editor

seq = SEQuence

shar = Shell ARchive

slrn = S-Lang rn

ssh = Secure Shell

ssl = Secure Sockets Layer

stty = Set TTY

su = Substitute User

svn = SubVersion

tar = Tape ARchive

tcsh = TENEX C shell

tee = T (T形水管接口)

telnet = TEminaL over Network

termcap = terminal capability

terminfo = terminal information

tex = τέχνη的缩写，希腊文art

tr = traslate

troff = Typesetter new ROFF

tsort = Topological SORT

tty = TeleTypewriter

twm = Tom's Window Manager

tz = TimeZone

udev = Userspace DEV

ulimit = User's LIMIT

umask = User's MASK

uniq = UNIQue

i = VIsual = Very Inconvenient

vim = Vi IMproved

wall = write all

wc = Word Count

wine = WINE Is Not an Emulator

xargs = eXtended ARGuments

xdm = X Display Manager

xlfd = X Logical Font Description

xmms = X Multimedia System

xrdb = X Resources DataBase

xwd = X Window Dump

yacc = yet another compiler compiler

Fish = the Friendly Interactive SHell

su = Switch User

MIME = Multipurpose Internet Mail Extensions

ECMA = European Computer ManufacturersAssociation