useful commands

linux添加用户的相关命令

1. useradd 添加用户 useradd -d /home/wengqiang -m wengqiang -s /bin/bash 创建用户wengqiang

2. usermod 修改创建用户的相关属性 usermod -s /bin/sh wengqiang 修改用户wengqiang的登录shell

usermod -aG sudo wengqiang 将用户wengqinag加入到sudo group中

3. passwd 修改用户的密码 passwd wengqiang

修改文件的owner以及group

chown owner_name:group_name file_name

linux|mac 产生随机串

1. linux上 cat /dev/urandom | tr -dc A-Z9 | head -c ${1:-81}
2. mac上 cat /dev/urandom | LC_ALL=C tr -dc 'A-Z9' | fold -w 81 | head -n 1

windows下验证校验码命令

Certutil(Certutil /?)

certutil -hashfile xxx MD5
certutil -hashfile xxx SHA1
certutil -hashfile xxx SHA256

获取本机ip

curl https://ip.cn

使用openssl生成secp256k1的key-pair

1. 生成 openssl ecparam -name secp256k1 -genkey -out ec-priv.pem

2. 输出 openssl ec -in ec-priv.pem -text -noout

linux 磁盘相关命令

1. blkid 列出机器上设备的uuid或label等信息

2. pvdisplay|pvcreate 显示physical volume相关信息或者创建physical volume

3. lvdisplay|lvcreate|vgextend vgdisplay|vgcreate|vgextend

clang&g++显示类的内存分布

clang++ -cc1 -emit-llvm -fdump-record-layouts thefile.cpp g++ -fdump-class-hierarchy -c test.cpp

go

1. go-wrk http benchmark utility go get github.com/adjust/go-wrk

2. go tool pprof get profile info of the program

add following line in import part import _ net/http/pprof

go tool pprof --seconds=5 localhost:8000/debug/pprof/profile

3. go-torch go get github.com/uber/go-torch

检测端口是否使用

1. tcp port telnet ip port

2. udp port netcat(nc) -vnzu ip port

windows添加启动程序

1. 用户下 win + r shell:startup 打开当前用户的启动目录，将程序的快捷方式放入其中即可

2. 系统下 "C:Menu"

安装bundle插件

1. install Vundle.vim in .../bundle folder
2. nvim +PluginInstall +qall

linux下查看c++编译后的symbols

nm a.out | grep c++filt

vim 保存时获得sudo权限

:w !sudo tee %

查看连接的top10的用户ip

netstat -nat | awk '{print $5}' | awk -F ':' '{print $1}' | sort | uniq -c | sort -rn | head -n 10

查看最常用10个命令

cat .bash_history | sort | uniq -c | sort -rn | head -n 10

ubuntu下查看以及修改core dump location

sysctl kernel.core_pattern or cat /proc/sys/kernel/core_pattern
sudo sysctl -w kernel.core_pattern=/tmp/mydumps/core_%e.%p_%t

compile gcc[missing prerequisites]

1. inside the gcc source dir, download ./contrib/download_prerequisites
2. missing gengtype-lex.cc sudo apt install flex
3. build gcc ``

search linux shell command by prefix

1. ctrl + r
   type ctrl + r then type command prefix, you can keep typing ctrl + r to cycle previous matching commands
2. ctrl + s
   search backwards in history.