Linux sudo xxxx:command not found问题

在/usr/local/目录下安装了nginx，并将nginx/sbin加入PATH，却提示:command not found。

# 切换到root用户
$ vim /etc/profile  
export PATH=$PATH:/usr/local/nginx/sbin  
$ source /etc/profile  
$ which nginx
/usr/local/nginx/sbin/nginx
$ nginx -t #到这里是OK的

#切换到普通用户，比如test用户
$ nginx -t
nginx: [warn] the "user" directive makes sense only if the master process runs with super-user privileges, ignored in /usr/local/nginx/conf/nginx.conf:2
nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: [emerg] open() "/vdb/logs/nginx/nginx.pid" failed (13: Permission denied)
nginx: configuration file /usr/local/nginx/conf/nginx.conf test failed
#从输出来看，这是权限不够原因。

$ sudo nginx -t
sudo nginx:commmand not found
#加上sudo又提示找不到此命令
#明明把nginx加入了PATH环境变量，为啥使用sudo，还找不到nginx这个命令了呢？

#经过一番苦苦思考与百度，发现只有在“/etc/sudoers”里面的secure_path指定目录下的命令才可以使用sudo。
$ cat /etc/sudoers
......
Defaults    secure_path = /sbin:/bin:/usr/sbin:/usr/bin
......

#解决方法：把nginx连接到/usr/bin下
$ ln -s /usr/local/nginx/sbin/nginx /usr/bin
$ sudo nginx -t 
nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful