如何使用exec（）系列实现shell命令cp和rm？

Question

how can I implement cp and rm shell commands using exec() family system calls ? I've searched a lot but did'nt find any helpful site/link ,can someone help please ???

Answer 1

Here's are examples.

The exec functions with l in their name take the list of arguments as their own arguments. The p suffix means that the command should be found using $PATH , so you can just supply the command name.

execlp("cp", "cp", "sourcefile", "destfile", (char *)0);

The variants with v take the argument in a single array argument ("v" stands for vector ). In this case, I didn't use the e suffix, so I gave the full path to the program.

char *args[] = {"rm", "file1", "file2", 0);
execv("/bin/rm", args);

In both cases, the first argument is also the name of the program, since this will become argv[0] in the new process. And the end of arguments is signified with a null pointer. You should provide the typecast explicitly when using the l variants, since varargs functions don't do automatic type conversion to pointers.