根据输入网络服务名称取得端口号

查看/etc/services文件，可以浏览所有网络服务名对应的端口号，由于文件列表太长，不方便查阅，就写个正则表达式的shell来指定特别的服务名称查询对应的端口号，或者根据端口号来查询对应的服务名称。

1. #!/bin/bash
2. read -p "choose service_name or port_number, 1:service, 2:port: " num
3. case $num in
4. "1")
5.         read -p "type the service name: " service_name
6.         grep "^$service_name .*" /etc/services |grep 'tcp'|awk '{print $2}'|awk 'BEGIN{FS="/"} {print "port number is " $1}'
7.       ;;
8. "2")
9.         read -p "type the port number: " port_num
10.         grep "^.* $port_num/" /etc/services |grep 'tcp'|awk '{print "service name is " $1}'
11.         ;;
12. *)
13.         echo "1:service name 2:port number"
14.         ;;
15. esac

1. choose service_name orport_number, 1:service, 2:port: 1
2. type the service name: http
3. port number is 80

1. choose service_name or port_number, 1:service, 2:port: 2
2. type the port number: 21
3. service nameis ftp