首先要查看一下ssh命令存在何处

# which ssh

   /usr/bin/ssh

使用ssh的绝对路径 

# /usr/bin/ssh slave1
Welcome to Ubuntu 16.04 LTS (GNU/Linux 4.4.0-21-generic x86_64)

* Documentation: https://help.ubuntu.com/

545 packages can be updated.
240 updates are security updates.

<Linux> SSH配置之后 SHH slave1 测试 error：SSH: command not found