|EXEC(3)||Library Functions Manual||EXEC(3)|
extern char **environ;
char *path, const char
char *file, const char
char *path, const char
char *const envp);
char *path, char *const
char *file, char *const
execfamily of functions replace the current process image with a new process image. The functions described in this manual page are front-ends for the function execve(2). (See the manual page for execve for detailed information about the replacement of the current process.)
The initial argument for these functions is the pathname of a file which is to be executed.
The const char *arg and subsequent ellipses
execle() functions can be thought of as
arg0, arg1, ...,
argn. Together they describe a list of one or more
pointers to NUL-terminated strings that represent the argument list
available to the executed program. The first argument, by convention, should
point to the file name associated with the file being executed. The list of
arguments must be terminated by a null pointer.
execvp() functions provide an array of pointers to
NUL-terminated strings that represent the argument list available to the new
program. The first argument, by convention, should point to the file name
associated with the file being executed. The array of pointers
must be terminated by a null pointer itself.
execle() function also specifies the
environment of the executed process by following the null pointer that
terminates the list of arguments in the parameter list or the pointer to the
argv array with an additional parameter. This
additional parameter is an array of pointers to NUL-terminated strings and
must be terminated by a null pointer itself. The other
functions take the environment for the new process image from the external
variable environ in the current process.
Some of these functions have special semantics.
execvp() will duplicate the actions of the shell in
searching for an executable file if the specified file name does not contain
a slash (‘/’) character. The search path is the path specified
in the environment by
PATH variable. If this
variable isn't specified,
⟨paths.h⟩ is used instead, its value
In addition, certain errors are treated specially.
If permission is denied for a file (the attempted
EACCES), these functions will continue searching the
rest of the search path. If no other file is found, however, they will
return with the global variable errno set to
If the header of a file isn't recognized (the attempted
ENOEXEC), these functions will execute the shell
with the path of the file as its first argument. (If this attempt fails, no
further searching is done.)
execfunctions return, an error has occurred. The return value is -1, and the global variable errno will be set to indicate the error.
execvp() may fail and set errno for any of the errors specified for the library functions execve(2) and malloc(3).
execv() may fail and set
errno for any of the errors specified for the library
execvp() functions was .:/bin:/usr/bin. This was changed to improve security and behaviour.
The behavior of
execvp() when errors occur while attempting to
execute the file is historic practice, but has not traditionally been
documented and is not specified by the POSIX standard.
Traditionally, the functions
execvp() ignored all errors except for the ones
described above and
E2BIG, upon which they returned. They now return if
any error other than the ones described above occurs.
execvp() conform to IEEE Std
|May 31, 2007||OpenBSD-5.1|