Where does the OS store the command line arguments?

I am working on Linux. In which section of memory are the command line arguments stored (stack or heap)?

I tried to execute free(argv) and I got a segmentation fault. Wh开发者_Python百科y is that?

I tried to execute free(argv) and I got a segmentation fault. Why is that?

You can only free what you malloc/calloc (and possibly realloc later on). Trying to free something else invokes Undefined Behaviour. One (good) way UB manifests itself is by producing a segmentation fault; a (bad) way is to make the program appear to work as intended.

As to where they are ... read section 5.1.2.2.1 of the C99 Standard -- its unspecified.

the strings pointed to by the argv array shall be modifiable by the program, and retain their last-stored values between program startup and program termination.

I am working on Linux. In which section of memory are the command line arguments stored (stack or heap)?

That's up to the implementation; check your compiler documentation. All that's required is that that argc and argv, as well as the strings that the argv array points to, be modifiable by the program.

I tried to execute free(argv) and I got a segmentation fault. Why is that?

You didn't allocated argv with malloc. You don't need to free the command line argument vectory.