# TL;dr ```bash # quietly add a user without password adduser --quiet --disabled-password --shell /bin/bash --home /home/newuser --gecos "User" newuser # set password echo "newuser:newpassword" | chpasswd nc -w 1 qq.com 80 < /dev/null && echo "tcp port ok" pstree -c -p -s -S -h -a 17648 ``` ```bash [ -f /etc/passwd ] && ( echo "1" ) || : sudo pipinstall ngxtop sudo yum install -y libpcap libpcap-devel sudo yum install -y epel-release sudo yum install -y nethogs nload /usr/bin/ncat --listen -4 -vvv --keep-open --wait 50 --sh-exec "cat -n | tee -a ./out.txt" 8080 /usr/bin/ncat --listen -4 --verbose --keep-open --wait 50 --sh-exec "cat -n | tee -a ./out.txt" 9090 /usr/bin/nping -4 --verbose -c 1 -p 9090 localhost python3 -c "import socket;print([(s.connect(('8.8.8.8', 53)), s.getsockname()[0], s.close()) for s in [socket.socket(socket.AF_INET, socket.SOCK_DGRAM)]][0][1])" ip a |grep |awk '{print $NF}' ip r |grep |cut -d " " -f 3 curl -w "TCP handshake: %{time_connect}, SSL handshake: %{time_appconnect}\n" -so /dev/null https://blog.ziki.cn journalctl -k --no-pager systemctl -a --no-pager systemctl list-unit-files --no-pager systemd-cgls --no-pager sysctl -a --ignore |& grep ipv4.ip_forward sysctl -a --ignore 2>&1 | grep ipv4.ip_forward sysctl -a --ignore 2>/dev/null | grep rp_filter sysctl -a --ignore 2>&1 | grep ipv4.ip_ sysctl --all --ignore 2>&1 |wc -l ``` ```bash ## shell下循环输出 1-10 # 方法1 for i in {1..10};do echo $i;done # 方法2 for i in $(seq 1 10);do echo $i;done # 方法3 for ((i=1;i<=10;i++)); do echo $i;done ## shell下计算 5+6 # 方法1 let a=5;b=6;let c=a+b;echo $c # 方法2 a=5;b=6;c=$((a+b)); echo $c ## shell下判断 /tmp/f 目录是否存在,如果不存在则创建目录 # 方法1 [ -d /tmp/f ] || { mkdir -p /tmp/f; } # 方法2 if [ ! -d "/tmp/f" ]; then mkdir /tmp/f; fi ``` # ref * [Linux Static IP Configuration | Linode](https://www.linode.com/docs/networking/linux-static-ip-configuration/) * [30 个方便的 Bash shell 别名 - 众成翻译](https://www.zcfy.cc/article/30-handy-bash-shell-aliases-for-linux-unix-mac-os-x) * [curl基础使用](https://testudy.cc/tech/2017/03/22/curl-basic.html) systemctl disable firewalld systemctl stop firewalld systemctl restart docker