1.登录之后显示$,无法使用table自动补齐,打开bash
bash
2.无法使用ll命令
alias ll=‘ls -alF’
3.删除文件/文件夹
rm -f/rm -rf
4.文件夹重命名A->B
mv A B
5.ftp命令
登录：
ftp hostname port
username
passwd
ftp -> open host
路径：
ftp中用lcd切换本地路径，用cd切换远程服务器的路径。
cd目录名（进入服务器目录） lcd目录名（进入本机目录）
cd \（退到服务器根目录） lcd \（退到本机根目录）
cd …（退回到上一级目录） lcd …（退回到上一级目录）
!dir（显示本机当亲目录内容） dir（显示服务器当前目录内容）
文件：
get filename
put/send filename
6.top
动态查看系统进程运行情况
7.nice
以指定的优先级运行某个进程
nice -9 ./while.py 以9的优先级运行程序
sudo nice --9 ./while.py 以-9的优先级运行程序
renice n PID 修改一个正在运行的进程的优先级
8.ps
ps -A
ps -afx
ps -aux
9.查看内核版本
uname -r
10.查看操作系统版本
cat /proc/version
cat /etc/issue
11.netstat
netstat -in
i:接口
n:ip地址
rn:查看路由(==route)
12.arp -a
查看arp高速缓存
13.arp -d
删除arp高速缓存表项
14.ping
15.tracepath
16.tcpdump -i ens33 -nn icmp
i:接口
nn:网络协议
17.route add
添加路由
18.cat /proc/sys/net/ipv4/ip_forward
查看是否支持路由转发
19.替换文件中的字符串
将当前目录中所有文件中的字符串"src"替换为"sbu1"(区分大小写)
sed -i “s/src/sbu1/g” grep "src" -rl ./
sed -i “s/SRC/SBU1/g” grep "SRC" -rl ./
20.apt-get install packagename
出现E:packagename has no installation candidate
解决：
apt-get update
apt-get upgrade
apt-get install packagename
21.修改默认源（apt-get软件包来源）
安装Ubuntu 18.04后，使用国外源太慢了，修改为国内源会快很多。
修改阿里源为Ubuntu 18.04默认的源
备份/etc/apt/sources.list
cp /etc/apt/sources.list /etc/apt/sources.list.bak
在/etc/apt/sources.list文件前面添加如下条目
添加阿里源：
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
最后执行如下命令更新源：
sudo apt-get update
sudo apt-get upgrade
另外其他几个国内源如下：
中科大源
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
163源
deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
清华源
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
22.修改ubuntu（16.04以上）默认运行级别
systemctl set-default multi-user.target
23.查看CPU是否支持虚拟化
egrep -o ‘(vmx|svm)’ /proc/cpuinfo
egrep ‘(vmx|svm)’ /proc/cpuinfo
24.安装KVM环境（嵌套虚拟化）
sudo apt-get install -y qemu-kvm qemu-system libvirt-bin virt-manager bridge-utils vlan
25.安装openvswitch
apt-get install openvswitch-switch
26.安装docker
apt install docker.io
27.docker加速
curl -sSL https://get.daocloud.io/daotools/set_mirror.sh | sh -s http://95822026.m.daocloud.io
systemctl restart docker.service
28.ubuntu安装PCRE库
apt-get install libpcre3 libpcre3-dev