Home Man
Search
Today's Posts
Register

Linux & Unix Commands - Search Man Pages

RedHat 9 (Linux i386) - man page for execve (redhat section 2)

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 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-uid bit is set on the program file pointed to by filename the effective user ID
       of  the	calling  process is changed to that of the owner of the program file.  Similarly,
       when the set-gid 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  typi-
       cally  /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	appropri-
       ately.

ERRORS
       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 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 format 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,  or	a  shared
	      library needed for file or interpreter cannot be found.

       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.

       ETXTBSY
	      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 segment (i.e.,  tried  to  name  more
	      than one interpreter).

       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,  ENOLINK,
       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.

       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  suc-
       cessfully.

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

SEE ALSO
       chmod(2), fork(2), execl(3), environ(5), ld.so(8)

Linux 2.0.30				    1997-09-03					EXECVE(2)


All times are GMT -4. The time now is 11:19 PM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
UNIX.COM Login
Username:
Password:  
Show Password