Fix C External Command Errors

If there is a parsing error when using an external command in C language, it may be because the system cannot find the command or the command format is incorrect. Solutions include:

1. Ensure that the external command is properly installed in the system and its path has been added to the system’s environment variables.
2. Check the syntax of calls to external commands in the code to ensure that the command’s arguments and format meet the requirements.
3. If the external command is a custom script or program, it may require manual compilation or configuration of the path in order to be called correctly.
4. You can test if an external command runs properly using the system command line to confirm if the issue lies within the code.
5. If the methods mentioned above do not work, you can try using system call functions such as system() or popen() to execute external commands, which allows for more flexible handling of command execution results and error messages.