make -n //dry-run

make SHELL='sh -vx'

检查内核版本

通过uname -r命令检查内核版本是否大于4.9

# uname -r

启用BBR拥塞算法

• 加载内核模块

# modprobe tcp_bbr

# echo "tcp_bbr" >> /etc/modules-load.d/modules.conf

• 修改内核参数

# echo "net.core.default_qdisc=fq" >> /etc/sysctl.conf

very old  https://gist.github.com/mondain/b0ec1cf5f60ae726202e

some fix https://gist.github.com/zziuni/3741933

23.21.150.121:3478

iphone-stun.strato-iphone.de:3478

numb.viagenie.ca:3478

s1.taraba.net:3478

s2.taraba.net:3478

stun.12connect.com:3478

stun.12voip.com:3478

stun.1und1.de:3478

stun.2talk.co.nz:3478

stun.2talk.com:3478

stun.3clogic.com:3478

stun.3cx.com:3478

stun.a-mm.tv:3478

stun.aa.net.uk:3478

stun.acrobits.cz:3478

stun.actionvoip.com:3478

ssh -o ProxyCommand="ssh -W %h:%p root@jump.example.org" root@target.example.org

or write it to ssh config file

Host xxx

HostName target.example.org

User root

IdentityFile ~/.ssh/id_rsa

ProxyCommand ssh -W %h:%p root@jumphost.example.org

another

ssh -L local_Port:target.example.org:22 root@jumphost.example.org

write it to ssh config file using LocalForward

//computer one ip from ifconfig 192.168.1.2  public ip 2.2.2.2  
ip tunnel del ipip0
ip tunnel add ipip0 mode ipip remote 1.1.1.1 local 192.168.1.2
ip addr add 10.0.0.101/24 dev ipip0
ip link set ipip0 up

//computer two ip from ifconfig 192.168.100.2  public ip  1.1.1.1
ip tunnel del ipip0
ip tunnel add ipip0 mode ipip remote 2.2.2.2 local 192.168.100.2
ip addr add 10.0.0.102/24 dev ipip0
ip link set ipip0 up

//iptables

$ git remote add xxx https://xxx.com/xxx.git

# push master to xxx

$ git push xxx master

# Push my-branch to xxx and set it to track xxx/my-branch

$ git push -u xxx my-branch

# Make some existing branch track xxx instead of origin

$ git branch --set-upstream other-branch xxx/other-branch

inherit enable_shared_from_this with public specifier

class a:pubic enable_shared_from_this{}

without pubic,make shared func can not set weak_ptr

so shared_from_this will throw  bad_weak_ptr

echo "djdjjd"|wc -c

wc -l //count line

echo $((0x41FE))

printf %d\\n 0x41FE

echo 'ibase=16;obase=10; 41FE'|bc    //need upper case

on linux obase=10;  need to change to obase=A;  or leave space  echo 'ibase=16; 41FE'|bc

test on mac and gentoo

1.      “.”： 匹配除"\n"之外的任何单个字符，若要匹配包括"\n"在内的任意字符，需使用诸如"[\s\S]"之类的模式；

2.       “^”：匹配输入字符串的开始位置，不匹配任何字符，要匹配”^”字符本身，需使用”\^”；

3.      “$”：匹配输入字符串结尾的位置，不匹配任何字符，要匹配”$”字符本身，需使用”\$”；

4.      “*”： 零次或多次匹配前面的字符或子表达式，”*”等效于”{0,}”，如”\^*b”可以匹配”b”、”^b”、”^^b”、…；

5.      “+”： 一次或多次匹配前面的字符或子表达式，等效于”{1,}”，如”a+b”可以匹配”ab”、”aab”、”aaab”、…；

6.      “?”： 零次或一次匹配前面的字符或子表达式，等效于”{0,1}”，如”a[cd]?”可以匹配”a”、”ac”、”ad”； 当此字符紧随任何其他限定符”*”、”+”、”?”、”{n}”、”{n,}”、”{n,m}”之后时，匹配模式是"非贪心的"。"非贪心的"模式匹配搜索到的、尽可能短的字符串，而默认的"贪心的"模式匹配搜索到的、尽可能长的字符串。如，在字符串"oooo"中，"o+?"只匹配单个"o"，而"o+"匹配所有"o"；