ARM-linux-gcc cross-compilation tool prompts arm-linux-gcc can not find

        1: 1: Normally, unzip and install the cross-tool in the user directory.

                  2: Use sudo /etc/profile to change the corresponding environment variables. (For more information, see the cross-tool installation in the OK6410Llinux user manual)

                  3: source /etc/profile to make the modified file take effect

                  4: Check whether the cross-tool is effective: arm-linux-gcc -V

　　The above prompts you to install the cross tool chain version information, but when you compile the kernel, the system will prompt an error that some files cannot be executed, so I added sudoo and tried to compile it through sudoo permissions. The structure is not good and it prompts arm-linux-gcc can not find,.... What's the matter? What's the matter? ? ? ? ?

       The solution is as follows:

               A: sudo -s command, this is the command that Ubuntu switches to root privileges

                B: vi /etc/profile command, you will find that this is not the file modified in the previous step? Yes, it is the file you modified and saved with sudo vi /etc/profile under user permissions. We do not need to modify it again here. The key is in the third point below

                C：　source /etc/profile。

　　　　  D: Check whether the cross-tool is effective: arm-linux-gcc -v

　　　　　E: Compile your file and find that the tool is easy to use and does not prompt errors

　Summary: The reason is that we need the super privilege ROOT to compile files. The cross-compilation tool installed under user privileges cannot be found when compiling files with super privileges. It is equivalent to you being an arms supplier and having many guns, but sorry, only the police have the privilege to use the guns and ammunition. Ordinary users cannot use them without privileges. What should you do? You have to tell the police how to use these weapons through the "instruction manual". sudo -S switches to ROOT privileges, and source /etc/profile under root privileges to register the relevant cross-tool information for root.