EXECVE(2)           Linux Programmer's Manual           EXECVE(2)

NAME
       execve - execute program

SYNOPSIS
       #include <unistd.h>

       int  execve  (const  char  *filename, char *const argv [],
       char *const envp[]);

DESCRIPTION
       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 path-
       name for an executable which is not itself a script, which
       will be invoked as interpreter [arg] filename.

       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
       parent process are cleared.  Any signals set to be  caught
       by   the  calling  process  are  reset  to  their  default
       behaviour.

       If the current program is being ptraced, a SIGTRAP is sent
       to it after a successful execve().

       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 execu-
       tion 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.

RETURN VALUE
       On success, execve() does  not  return,  on  error  -1  is
       returned, and errno is set appropriately.

ERRORS
       EACCES  The  file or a script interpreter is not a regular
               file.

       EACCES  Execute permission is denied for  the  file  or  a
               script interpreter.

       EACCES  The file system is mounted noexec.

       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.

       E2BIG   The argument list is too big.

       ENOEXEC An  executable  is  not in a recognised format, is
               for the wrong architecture, or has some other for-
               mat error that means it cannot be executed.

       EFAULT  filename  points  outside  your accessible address
               space.

       ENAMETOOLONG
               filename is too long.

       ENOENT  The file filename or a script or  ELF  interpreter
               does not exist.

       ENOMEM  Insufficient kernel memory was available.

       ENOTDIR A  component  of  the path prefix of filename or a
               script or ELF interpreter is not a directory.

       EACCES  Search permission is denied on a component of  the
               path  prefix  of  filename or the name of a script
               interpreter.

       ELOOP   Too  many  symbolic  links  were  encountered   in
               resolving  filename or the name of a script or ELF
               interpreter.

       ETXTBUSY
               Executable was open for writing  by  one  or  more
               processes.

       EIO     An I/O error occurred.

       ENFILE  The limit on the total number of files open on the
               system has been reached.

       EMFILE  The process has the maximum number of files  open.

       EINVAL  An ELF executable had more than one PT_INTERP seg-
               ment (i.e., tried to name  more  than  one  inter-
               preter).

       EISDIR  An ELF interpreter was a directory.

       ELIBBAD An ELF interpreter was not in a recognised format.

CONFORMING TO
       SVr4, SVID, X/OPEN, BSD 4.3.  POSIX does not document  the
       #!   behavior but is otherwise compatible.  SVr4 documents
       additional error conditions EAGAIN, EINTR,  ELIBACC,  ENO-
       LINK,  EMULTIHOP;  POSIX does not document ETXTBSY, EPERM,
       EFAULT, ELOOP, EIO,  ENFILE,  EMFILE,  EINVAL,  EISDIR  or
       ELIBBAD error conditions.

NOTES
       SUID and SGID processes can not be ptrace()d SUID or SGID.

       A maximum line length of 127 characters is allowed for the
       first line in a #! executable shell script.

       Linux ignores the SUID and SGID bits on scripts.

SEE ALSO
       ld.so(8), execl(3), fork(2)

Linux 2.0.30             3 September 1997                       1