Shell cmd set note

1,expr

a)expr calculate//a=10;echo `expr $a - 1 `

b)string index //a=‘abcde‘;echo `expr index $a "b"`|| string substr// a=‘abcde‘; echo `expr substr $a 2 3`

c)regrexp// a=

2,echo

a)string len//echo ${#a} ||string index//echo ${a:1:4}

centOs install emacs-nox :yum -y install emacs-nox

3,ps -ef | grep docker | grep -v "color=auto" | awk -F " " ‘{print $2}‘ | xargs kill -9 //stop all docker process

4,awk

[email protected]:~> yes | head -5 | awk ‘{printf("user_%d 12345 user_%[email protected]\n",NR,NR)}‘

user_1 12345 [email protected]
...

5,ps axw -o pid,ppid,user,%cpu,vsz,wchan,command | egrep ‘(nginx|PID)‘