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execve - execute program
int execve(const char *filename, char *const argv , char *const
execve() executes the program pointed to by filename. filename must be
either a binary executable, or a script starting with a line of the
form "#! interpreter [arg]". In the latter case, the interpreter must
be a valid pathname for an executable which is not itself a script,
which will be invoked as interpreter [arg] filename.
argv is an array of argument strings passed to the new program. envp
is an array of strings, conventionally of the form key=value, which are
passed as environment to the new program. Both argv and envp must be
terminated by a null pointer. The argument vector and environment can
be accessed by the called program’s main function, when it is defined
as int main(int argc, char *argv, char *envp).
execve() does not return on success, and the text, data, bss, and stack
of the calling process are overwritten by that of the program loaded.
The program invoked inherits the calling process’s PID, and any open
file descriptors that are not set to close-on-exec. Signals pending on
the calling process are cleared. Any signals set to be caught by the
calling process are reset to their default behaviour. The SIGCHLD
signal (when set to SIG_IGN) may or may not be reset to SIG_DFL.
If the current program is being ptraced, a SIGTRAP is sent to it after
a successful execve().
If the set-user-ID bit is set on the program file pointed to by
filename, and the calling process is not being ptraced, then the
effective user ID of the calling process is changed to that of the
owner of the program file. Similarly, when the set-group-ID bit of the
program file is set the effective group ID of the calling process is
set to the group of the program file.
If the executable is an a.out dynamically-linked binary executable
containing shared-library stubs, the Linux dynamic linker ld.so(8) is
called at the start of execution to bring needed shared libraries into
core and link the executable with them.
If the executable is a dynamically-linked ELF executable, the
interpreter named in the PT_INTERP segment is used to load the needed
shared libraries. This interpreter is typically /lib/ld-linux.so.1 for
binaries linked with the Linux libc version 5, or /lib/ld-linux.so.2
for binaries linked with the GNU libc version 2.
On success, execve() does not return, on error -1 is returned, and
errno is set appropriately.
E2BIG The total number of bytes in the environment (envp) and argument
list (argv) is too large.
EACCES Search permission is denied on a component of the path prefix of
filename or the name of a script interpreter. (See also
EACCES The file or a script interpreter is not a regular file.
EACCES Execute permission is denied for the file or a script or ELF
EACCES The file system is mounted noexec.
EFAULT filename points outside your accessible address space.
EINVAL An ELF executable had more than one PT_INTERP segment (i.e.,
tried to name more than one interpreter).
EIO An I/O error occurred.
EISDIR An ELF interpreter was a directory.
An ELF interpreter was not in a recognised format.
ELOOP Too many symbolic links were encountered in resolving filename
or the name of a script or ELF interpreter.
EMFILE The process has the maximum number of files open.
filename is too long.
ENFILE The system limit on the total number of open files has been
ENOENT The file filename or a script or ELF interpreter does not exist,
or a shared library needed for file or interpreter cannot be
An executable is not in a recognised format, is for the wrong
architecture, or has some other format error that means it
cannot be executed.
ENOMEM Insufficient kernel memory was available.
A component of the path prefix of filename or a script or ELF
interpreter is not a directory.
EPERM The file system is mounted nosuid, the user is not the
superuser, and the file has an SUID or SGID bit set.
EPERM The process is being traced, the user is not the superuser and
the file has an SUID or SGID bit set.
Executable was open for writing by one or more processes.
SVr4, SVID, X/OPEN, 4.3BSD. POSIX does not document the #! behavior
but is otherwise compatible. SVr4 documents additional error
conditions EAGAIN, EINTR, ELIBACC, ENOLINK, EMULTIHOP; POSIX does not
document ETXTBSY, EPERM, EFAULT, ELOOP, EIO, ENFILE, EMFILE, EINVAL,
EISDIR or ELIBBAD error conditions.
SUID and SGID processes can not be ptrace()d.
Linux ignores the SUID and SGID bits on scripts.
The result of mounting a filesystem nosuid vary between Linux kernel
versions: some will refuse execution of SUID/SGID executables when this
would give the user powers she did not have already (and return EPERM),
some will just ignore the SUID/SGID bits and exec() successfully.
A maximum line length of 127 characters is allowed for the first line
in a #! executable shell script.
With Unix V6 the argument list of an exec() call was ended by 0, while
the argument list of main was ended by -1. Thus, this argument list was
not directly usable in a further exec() call. Since Unix V7 both are
chmod(2), fork(2), path_resolution(2), ptrace(2), execl(3), environ(5),