Mastering Linux Kernel Development

exec

At times creating a child process might not be useful, unless it runs a new program altogether: the exec family of calls serves precisely this purpose. exec replaces the existing program in a process with a new executable binary:

#include <unistd.h>int execve(const char *filename, char *const argv[],char *const envp[]);

The execve is the system call that executes the program binary file, passed as the first argument to it. The second and third arguments are null-terminated arrays of arguments and environment strings, to be passed to a new program as command-line arguments. This system call can also be invoked through various glibc (library) wrappers, which are found to be more convenient and flexible:

#include <unistd.h>extern char **environ; ...