求助:命令失效

[argo-jason]

装JDK的时候改了环境变量.都是按网上做的,在这之前做过自动清理
(sudo apt-get autoremove)
重启机器,从字符终端登陆后,先会报
ubuntu comes with absolutely no warranty,to the context permitted by applicable law.
-bash:lesspipe
-bash:command
-bash:dircolors
-bash:command
-bash:the
......
然后,
发现大部分命令失效.比如打cat,sudo,ls,vi,有以下类似错误
Command 'cat' is abaiable in '/bin/cat'
The command could not be located because '/bin' is not included the PATH evnironment variable
能用的就只有cd,pwd
说是环境变量的问题,但现在连vi编辑器都打不开,无法修改环境变量文件,
请教各位,我该怎么办?