include <stdlib.h>
void abort(void) - Abort a process.
int execl(char *path, char *argO, char *arg1,..., NULL) - Launch a child process (pass command line).
int execlp(char *path, char *argO, char *arg1,..., NULL) - Launch child (use PATH pass command line).
int execv(char *path, char *argv[]) - Launch child (pass argument vector).
int execvp(char *path, char *argv[]) - Launch child (use PATH, pass argument vector).
void exit(int status) - Terminate process after flushing all buffers.
char *getenv(char *varname) - Get definition of environment variable,
void perror(char *string) - Print error message corresponding to last system error.
int putenv(char *envstring) - Insert new definition into environment table.
int raise(int signum) - Generate a C signal (exception).
void (*signat(int signum, void(*func)(jnt signum [, int subcode])))(int signum) - Establish a signal handler for signal number signum.
int system(char *string) - Execute a UNIX (or resident operating system) command.