Linux下command not found(以CentOS下没有telnet为例)
[root@localhost ~]# telnet
bash: telnet: command not found
rpm -qa telnet* //查询是否安装了Telnet包
yum list telnet* //查看telnet相关的安装包
yum install telnet-server //安装telnet服务
yum install telnet.* //安装telnet客户端
chkconfig telnet on //或者将 /etc/xinetd.d/telnet 文件里的 disable值设为no