Solve the Problems Related to the unavailability of basic centos5.6 commands

1. Recently, it was found that a server cannot use basic commands on linux, including ifconfig and vi. No matter what you enter
-Bash: vi: command not found.
2. Find the reason on the Internet. It may be because I modified the. bashrc file in the user's current directory a few days ago. This problem occurs only after I restarted it.
3. commands cannot be used, so we can use export to reset the bash environment variable.
Export PATH = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin: /usr/i686-pc-linux-gnu/gcc-bin/4.1.2:/usr/kde/3.5/sbin:/usr/kde/3.5/bin:/usr/qt/3/bin"
4. source/etc/profile to update the variable.
5. Someone said on the Internet that the absolute path of the linux system can also be changed. If you do not perform the test, you can try it in a similar situation in the future.