grep -E "[[:alnum:]]{4,18}@[[:alnum:]]{2,14}.(com|net|cn|org)" 1.txt //在1.txt中匹配查询邮箱地址
grep aaa 1.txt //在1.txt中查询aaa
grep -i aaa 1.txt //在1.txt中查询aaa,无论大小写
grep -ni aaa 1.txt //在1.txt中查询aaa,显示行号并无论大小写
grep -n -i aaa 1.txt //在1.txt中查询aaa,显示行号并无论大小写
grep -ni aaa 1.txt 2.txt //在多个文件中查询aaa,显示行号并无论大小写
grep -r com //递归查询com
grep -r --exclude-dir=aaa com //递归查询com，排除aaa目录
ps -ef | grep -i redis
netstat -ant | grep 3357
ps aux |grep mysql
