Here is a table to summarize all seven of the exec family APIs:
| Exec API | Arguments: long format (l) | Arguments: short format (v) | PATH searched? (p) | Environment passed? (e) | API layer |
|
execl |
Y |
N |
N | N | Lib |
| execlp | Y | N | Y | N | Lib |
| execle | Y | N | N | Y | Lib |
| execv | N | Y | N | N | Lib |
| execvp | N | Y | Y | N | Lib |
| execvpe | N | Y | Y | Y | Lib |
| execve | N | Y | N | Y | SysCall |
The exec APIs format: exec<foo>, where <foo> is differing combinations of {l,v,p,e}.
All the listed APIs, on success, as we have learned, do not return at all. Only upon failure, would you see a return value; as per the usual norms, the global variable errno will get set to reflect the cause of the error, which can be conveniently looked up via the perror(3) or strerror(3) ...
