Shulou(Shulou.com)06/01 Report--

R1-005 Shell external command execution process, I believe that many inexperienced people do not know what to do, so this paper summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

(1) call the posix system fork function interface to create a copy of the command line Shell process (child process).

(2) in the running environment of the child process, find the location of the external command in the Linux file system. If the external command gives the full path, skip the find step.

(3) in the child process, replace the Shell copy and execution with the new program, when the parent process goes into hibernation and waits for the child process to finish execution.

(4) after the execution of the child process, the parent process then fetches the next command from the terminal.

Note: 1. At the initial stage of creation, the child process is exactly the same as the parent process, but the child process cannot change the parameter variables of the parent process.

2. Only the built-in command can change the property settings (environment variables) of the command line Shell.

After reading the above, have you mastered the method of executing the external commands of R1-005 Shell? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

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