.\" Hey Emacs! This file is -*- nroff -*- source.
.\" and Copyright (c) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified by Michael Haardt <michael@moria.de>
.\" Modified 1993-07-21 by Rik Faith <faith@cs.unc.edu>
.\" Modified 1994-08-21 by Michael Chastain <mec@shell.portal.com>:
.\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1999-11-12 by Urs Thuermann <urs@isnogud.escape.de>
.\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
.\" 2006-09-04 Michael Kerrisk <mtk.manpages@gmail.com>
.\"     Added list of process attributes that are not preserved on exec().
.\" 2007-09-14 Ollie Wild <aaw@google.com>, mtk
.\"     Add text describing limits on command-line arguments + environment
.\"
.\" Japanese Version Copyright (c) 1996 TABATA Tomohira
.\"         all rights reserved.
.\" Translated 1996-07-04, TABATA Tomohira <loba@k2.t.u-tokyo.ac.jp>
.\" Updated 1997-12-14, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated 2001-08-17, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated 2005-02-05, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated 2005-09-06, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2005-11-19, Akihiro MOTOKI
.\" Updated 2006-08-13, Akihiro MOTOKI, LDP v2.39
.\" Updated 2007-01-09, Akihiro MOTOKI, LDP v2.43
.\" Updated 2007-06-03, Akihiro MOTOKI, LDP v2.51
.\" Updated 2007-10-12, Akihiro MOTOKI, LDP v2.66
.\"
.TH EXECVE 2 2007-09-14 "Linux" "Linux Programmer's Manual"
.SH ̾
execve \- ץ¹Ԥ
.SH 
.B #include <unistd.h>
.sp
.BI "int execve(const char *" filename ", char *const " argv "[], "
.br
.BI "           char *const " envp []);
.SH 
.BR execve ()
ϡ\fIfilename\fP ˤäƻꤵ줿ץ¹Ԥ롣
\fIfilename\fP ϡХʥ¹Է
ʲηιԤǻϤޤ륹ץȤǤʤФʤʤ

.in +4n
.nf
\fB#!\fP \fIinterpreter \fP[optional-arg]
.fi
.in

Ԥξܺ٤ϡΡ֥󥿥ץ꥿ץȡפ򻲾ȤΤȡ

\fIargv\fP ϿץϤʸǤ롣
\fIenvp\fP ʸǤꡢŪ \fBkey=value\fP η
ƤꡢץδĶѿȤϤ롣
\fIargv\fP  \fIenvp\fP Ϥ NULL ݥ󥿤ǽäƤ
ɬפ롣ȴĶѿϡƤӽФ줿ץ main ؿ
ʲΤ褦뤳Ȥˤäƥǽˤʤ롣

.in +4n
.nf
int main(int argc, char *argv[], char *envp[])
.fi
.in

硢
.BR execve ()
֤ʤ
ơƤӽФΥץ text, data, bss, åϡ
ɤ߹ޤ줿ץˤäƾ񤭤롣

Υץब ptrace Ƥ硢
.BR execve ()

Υץ \fBSIGTRAP\fP 롣

.I filename
ǻꤵ줿ץե set-user-ID ӥåȤꤵƤꡢ
ե뤬¸ߤե륷ƥब
.I nosuid
.RB ( mount (2)

.B MS_NOSUID
ե饰) ǥޥȤƤ餺
ƤӽФץ ptrace Ƥʤ硢
ƤӽФץμ¸ (effective) 桼 ID 
ץեνͭ (owner) ѹ롣
Ʊͤˡץե set-group-ID ӥåȤꤵƤ硢
ƤӽФץͭ롼 ID 
ץեΥ롼פѹ롣

ץμ¸桼 ID ¸ (saved) set-user-ID ˥ԡ롣
Ʊͤˡ¸롼 ID ¸ set-group-ID ˥ԡ롣
Υԡϡset-user-ID / set-group-ID ĥӥåȤˤȯ
¸ ID ѹ˹Ԥ롣

¹ԥե뤬ưŪ󥯤줿 a.out ¹Էǡͭ饤֥
֤ޤΤä硢¹Ԥγϻ Linux 
ʥߥå
.BR ld.so (8)
ƤӽФ졢ɬפʶͭ饤֥ɤ߹ǥ󥯤Ԥ

¹ԥե뤬ʥߥå󥯤줿 ELF ¹Էä硢
PT_INTERP Ȥ˻ꤵ줿󥿥ץ꥿ɬפ
ͭ饤֥ (shared library) ɤ߹Τ˻Ѥ롣
̾󥿥ץ꥿ȤƤϡ
Linux libc 5 󥯤Хʥξˤ
\fI/lib/ld-linux.so.1\fP 
glibc 2 󥯤Хʥξˤ
\fI/lib/ld-linux.so.2\fP Ѥ롣

ʲ˼ʳΤ٤ƤΥץ°
.BR execve ()
ݻ롣
.IP * 3
Ԥ (pending) Υʥ뽸ϥꥢ
.RB ( sigpending (2))
.IP *
ª줿ʥνˡ (disposition) ϡ̵פ˥ꥻåȤ롣
.IP *
إʥ륹åϤɤݻʤ
.RB ( sigaltstack (2))
.IP *
ޥåԥ󥰤ݻʤ
.RB ( mmap (2))
.IP *
ղä줿 (attached) System V ͭꥻȤʬΥ
.RB ( shmat (2))
.IP *
POSIX ͭΰϥޥåԥ󥰤
.RB ( shm_open (3))
.IP *
ץ󤵤줿 POSIX å塼ǥץϥ
.RB ( mq_overview (7))
.IP *
ץ󤵤줿 POSIX ̾դޥեϤ⥯
.RB ( sem_overview (7))
.IP *
POSIX ޤݻʤ
.RB ( timer_create (3))
.IP *
ץ󤵤줿ǥ쥯ȥꥹȥ꡼Ϥ⥯
.RB ( opendir (3))
.IP *
åݻʤ
.RB ( mlock (2),
.BR mlockall (2))
.IP *
λ (exit) ϥɥݻʤ
.RB ( atexit (3),
.BR on_exit (3))
.PP
嵭ΥꥹȤΥץ°Ϥ POSIX.1-2001 ǵꤵƤ롣
ʲ˼ Linux ͭΥץ°
.BR execve ()
ݻʤ
.IP * 3
set-user-ID  set-group-ID 줿ץब¹ԤƤ硢
.BR prctl (2)

.B PR_SET_DUMPABLE
ե饰ϥꥢ롣ʳξ硢Υե饰ϥåȤ롣
.IP *
.BR prctl (2)

.B PR_SET_KEEPCAPS
ե饰ϥꥢ롣
.IP *
ץ̾Ͽ¹ԥե̾˥ꥻåȤ롣
ץ̾
.BR prctl (2)

.B PR_SET_NAME
Ǥ
.I "ps \-o comm"
ɽǤ롣
.IP *
λʥ (termination signal) 
.B SIGCHLD
˥ꥻåȤ
.RB ( clone (2)
)
.PP
ʲˤĤƤդ뤳:
.IP * 3
ƤӽФåɰʳƤΥåɤ
.BR execve ()
˴롣
mutexѿ¾ pthread ֥Ȥݻʤ
.IP *
\fIsetlocale(LC_ALL, "C")\fP νץ೫ϻ˼¹Ԥ롣
.IP *
POSIX.1-2001 ϡư̵뤫ǥեȤꤵƤƤΥʥ
νˡѹΤޤޤˤ롢ȵꤷƤ롣
âPOSIX.1-2001 ˤϰ㳰ꡢ
.B SIGCHLD
̵ˤʤäƤ硢
νˡѹˤΤޤޤˤ뤫ǥեư˥ꥻåȤ뤫
¸ȤʤäƤ롣
Linux Ǥ (ѹʤ) ȤʤäƤ롣
.IP *
λƤʤƱ I/O ϥ󥻥뤵
.RB ( aio_read (3),
.BR aio_write (3))
.IP *
.BR execve (2)
ΥѥӥƥΰˤĤƤϡ
.BR capabilities (7)
򻲾ȡ
.IP *
ǥեȤǤϡեǥץ
.BR execve ()
ԤäǤ⥪ץ󤵤줿ޤޤǤ롣
close-on-exec ΰդƤեǥץϥ롣
.BR fcntl (2)

.B FD_CLOEXEC
򻲾ȡ
(եǥץȡΥץ
եǥץбեФƳƤ
쥳ɤΥåƲ뤳Ȥˤʤ롣)
POSIX.1-2001 Ǥϡ
եǥץ 0, 1, 2 
.BR execve ()
ˤɤǥ졢
¹Ԥե set-user_ID  set-group_ID εĥӥåȤ
åȤƤƥץø硢
ƥϲ餫Υե򥪡ץ󤹤ݤ
ֹΥǥץΤɤ줫ȤȤ롢
ȤƤ롣
§ȤơܿɬפʥץǤϡ
ø̵ͭ˴ؤ餺
.BR execve ()
Ǥ 3ĤΥեǥץ줿ޤޤ
뤳Ȥˤ뤳ȤϤǤʤ
.\" On Linux it appears that these file descriptors are
.\" always open after an execve(), and it looks like
.\" Solaris 8 and FreeBSD 6.1 are the same. -- mtk, 30 Apr 2007
.SS 󥿥ץ꥿ץ
󥿥ץ꥿ץȤȤϡ¹ԵĤͭˤʤäƤơ
ǽιԤʲηˤʤäƤƥȥեΤȤǤ롣

.in +4n
.nf
\fB#!\fP \fIinterpreter \fP[optional-arg]
.fi
.in

.I interpreter
ͭʼ¹ԥեΥѥ̾ǤʤФʤ餺
켫ȤץȤǤäƤϤʤʤ
.BR execve ()

.I filename
󥿥ץ꥿ץȤꤷƤ硢
.I interpreter
ϰʲΰǵư롣

.in +4n
.nf
\fIinterpreter\fP [optional-arg] \fIfilename\fP arg...
.fi
.in

.I arg...

.BR execve ()

.I argv
ؤǤ롣

ܿˤϡ
.I optional-arg
϶ 1ɤˤ٤Ǥ
(Ĥޤꡢۥ磻ȡڡޤ٤ǤϤʤ)
Ρաפ򻲾ȡ
.SS "ȴĶѿιץξ"
ۤȤɤ Unix μϡץϤȤǤ
ޥɥ饤
.RI ( argv )
ȴĶѿ
.RI ( envp )
ʸ󷲤ιץ˲餫ξ¤ߤƤ롣
POSIX.1 ϡ
.B ARG_MAX
ȤäƤξ¤ǧƤ
.RB ( ARG_MAX

.I <limits.h>
뤫¹Ի
.I "sysconf(_SC_ARG_MAX)"
θƤӽФǤ뤫Τ줫Ǥ)

ͥ 2.6.23  Linux ǤϡĶѿȰʸ󷲤
ǼΤ˻Ѥ 32 ڡ¤Ƥ
(32 ڡȤΤϥͥ
.B MAX_ARG_PAGES
)äơ
ڡ 4 kB ΥƥǤϡ
祵 128 kB ȤȤˤʤ롣

ͥ 2.6.23 ʹߤǤϡۤȤɤΥƥ
꥽ΥեȾ
.B RLIMIT_STACK
˴Ť¤Ȥ롣
ΥƥǤϡץξ¤ϵĤ줿å
1/4ʸξ¤ 32 ڡ (ͥ
.BR MAX_ARG_STRLEN )
ǡʸκͤ 0x7FFFFFFF Ǥ롣
(ѹˤꡢץϤޤǤ礭ʰĶѿ
ꥹȤˤʤ롣
ץ˥å 1/4 ξ¤ߤƤΤϡ
ץबɬ٤Υå֤Ƥ뤳Ȥݾڤ
Ǥ롣)
˥å (MMU) ʤƥϾ嵭ѹ
㳰Ǥ롣ΥƥǤϥͥ 2.6.23 
Ʊ¤Τޤ޻Ѥ롣
.\" Ollie: That doesn't include the lists of pointers, though,
.\" so the actual usage is a bit higher (1 pointer per argument).
.SH ֤

.BR execve ()
֤ʤ顼ξ \-1 ֤
.I errno
Ŭڤꤹ롣
.SH 顼
.TP
.B E2BIG
Ķѿ
.RI ( envp )
Ȱꥹ
.RI ( argv )
ιץХȿ礭᤮롣
.TP
.B EACCES
.I filename
䥹ץȥ󥿥ץ꥿̾ιǤ˸ (search permission)
ͿƤʤ
.RB ( path_resolution (7)
⻲Ȥ뤳)
.TP
.B EACCES
ե⤷ϥץȤΥ󥿥ץ꥿̾ե (regular file)
Ǥʤ
.TP
.B EACCES
ե䥹ץȤ ELF 󥿥ץ꥿
¹Ե (execute permission) ͿƤʤ
.TP
.B EACCES
ե롦ƥब
.I noexec
ǥޥȤƤ롣
.TP
.B EFAULT
.I filename
ǽʥɥ쥹֤γؤƤ롣
.TP
.B EINVAL
ELF ¹Էʣ PT_INTERP Ȥ¸ߤ롣
(ʤʣΥ󥿥ץ꥿ꤷ)
.TP
.B EIO
I/O 顼ȯ
.TP
.B EISDIR
ELF 󥿥ץ꥿ǥ쥯ȥä
.TP
.B ELIBBAD
ELF 󥿥ץ꥿ǤեޥåȤǤʤä
.TP
.B ELOOP
.I filename
䥹ץȤ ELF Υ󥿥ץ꥿褹ݤ
ܥå󥯤¿᤮롣
.TP
.B EMFILE
ΥץץǤեξ¤ޤǴ˥ץ󤷤Ƥ롣
.TP
.B ENAMETOOLONG
.I filename
Ĺ᤮롣
.TP
.B ENFILE
ΥƥǥץǤե¤ã
.TP
.B ENOENT
ե
.I filename
ץȤ ELF Υ󥿥ץ꥿¸ߤʤ
.TP
.B ENOEXEC
¹ԥե뤬ǤʤǤ뤫㤦ƥΤΤ
¾Υեޥåȡ顼ˤ¹ԤǤʤä
.TP
.B ENOMEM
ͥ˽ʬʥ꤬ʤ
.TP
.B ENOTDIR
.I filename
䥹ץȤ ELF Υ󥿥ץ꥿ιǤǥ쥯ȥǤʤ
.TP
.B EPERM
ե롦ƥब
.I nosuid
ǥޥȤ졢桼ѡ桼Ǥʤ
ե set-user-ID 뤤 set-group-ID ӥåȤꤵƤ롣
.TP
.B EPERM
ץȥ졼졢桼ѡ桼Ǥʤ
ե set-user-ID 뤤 set-group-ID ӥåȤꤵƤ롣
.TP
.B ETXTBSY
¹ԥե񤭹Ѥ˥ץ󤷤Ƥץ롣
.SH 
SVr4, 4.3BSD, POSIX.1-2001.
POSIX.1-2001 ˤ #! ưˤĤƤεҤϤʤ
¾ϸߴ롣
.\" SVr4 ˤ¾ EAGAIN, EINTR, ELIBACC, ENOLINK, EMULTIHOP
.\" ˤĤƤεҤ롣
.\" POSIX ˤ ETXTBSY, EPERM, EFAULT, ELOOP, EIO, ENFILE, EMFILE,
.\" EINVAL, EISDIR, ELIBBAD 顼֤ˤĤƤεҤϤʤ
.SH 
set-user-id ץ set-group-ID ץ
.BR ptrace (2)
Ǥʤ

Linux ϥץȤ set-user-ID  set-group-ID ӥåȤ̵뤹롣

ե륷ƥ
.I nosuid
ǥޥȤ set-user-ID/set-group-ID μ¹ԥե
ɤͤ˰ϡLinux ͥΥСˤäưۤʤ:
СǤϡǤɬפʸ¤äƤơ
μ¹Ԥݤ (
.B EPERM
֤)̤ΤСǤ
set-user-ID/set-group-ID ӥåȤΤߤ̵뤷
.BR exec ()
롣

#! ¹ԷΥ롦ץȤ 1ܤ˵Ƥʸϡ
 127 ʸǤ롣

󥿥ץ꥿ץȤ
.I optional-arg
βˡϼˤۤʤ롣
Linux Ǥϡ󥿥ץ꥿̾
.I interpreter
³ʸΤ󥿥ץ꥿ 1ĤΰȤϤ롣
ưۤʤ륷ƥ⤢롣
륷ƥǤϡ
.\" 㤨СSolaris 8
.I optional-arg
ΤǽΥۥ磻ȡڡޤǤ
ȤϤ롣
ޤ̤ΥƥǤ
.\" 㤨С6.0  FreeBSD (FreeBSD 6.0 ʹߤϰ㤦)
󥿥ץ꥿ץȤʣΰĤȤǤ
.I optional-arg
Υۥ磻ȡڡζڤȤʤ롣

Linux Ǥϡ
.I argv

.I envp
 NULL ꤹ뤳ȤǤ롣ϡΰ NULL ݥ
1ĤޤꥹȤؤΥݥ󥿤ꤷΤƱ̤ġ
.BR ֤δְäǽѤʤȡ 
ɸǡܿʤ
¾ΤۤȤɤ Unix ƥǤϡԤȥ顼ˤʤ롣
.\" e.g., EFAULT on Solaris 8 and FreeBSD 6.1; but
.\" HP-UX 11 is like Linux -- mtk, Apr 2007
.\" FIXME .
.\" Bug filed 30 Apr 2007: http://bugzilla.kernel.org/show_bug.cgi?id=8408
.\" Maybe this will get fixed (but it would constitute an ABI change).
.\"
.\" .SH Х
.\" Linux ǤˤϡELF 󥿥ץ꥿ˤ
.\" ¤Υå˼ԤΤ롣
.\" ϥƥۡǤ롣
.\" ʤʤ顢桼ǤդΥե򥪡ץĤꡢ
.\" ɤ߹ߤΤ˥ơץǥХ򴬤ᤷĤꤹ롣
.\" Linux Ǥˤ
.\" .BR execve ()
.\" ¾Υƥۡ뤬
.\" ¸ߤΤ⤢ꡢ̯˺ٹ줿 ELF Хʥˤä
.\" ӥ (denial of service) ѤƤޤ
.\" 2.0.34 ޤ 2.2.15 ˤϡΤƤϤʤ
.SS 
Unix V6 Ǥ
.BR exec ()
ΰꥹȤ 0 ǽü졢
.I main
ΰꥹȤ \-1 ǽüƤ
Τᡢ
.I main
ΰꥹȤϡθ
.BR exec ()
ˤľܻѤǤʤä
Unix V7 ʹߤǤϡȤ NULL ǽü롣
.SH 
ΥץϡʲܤΥץफ¹Ԥ뤿ΤΤǤ롣
ޥɥ饤 1Ԥ 1ĤɽΥץǤ롣

.in +4n
.nf
/* myecho.c */

#include <stdio.h>
#include <stdlib.h>

int
main(int argc, char *argv[])
{
    int j;

    for (j = 0; j < argc; j++)
        printf("argv[%d]: %s\\n", j, argv[j]);

    exit(EXIT_SUCCESS);
}
.fi
.in

ʲΥץϡޥɥ饤ǻꤷ̾Υץ
¹ԤΤ˻Ȥ

.in +4n
.nf
/* execve.c */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>

int
main(int argc, char *argv[])
{
    char *newargv[] = { NULL, "hello", "world", NULL };
    char *newenviron[] = { NULL };

    assert(argc == 2);  /* argv[1] identifies
                           program to exec */
    newargv[0] = argv[1];

    execve(argv[1], newargv, newenviron);
    perror("execve");   /* execve() only returns on error */
    exit(EXIT_FAILURE);
}
.fi
.in

ܤΥץȤäưܤΥץ¹Ԥˤ
ʲΤ褦ˤ롣

.in +4n
.nf
$ cc myecho.c -o myecho
$ cc execve.c -o execve
$ ./execve ./myecho
argv[0]: ./myecho
argv[1]: hello
argv[2]: world
.fi
.in

ˡΥץȤäơץȡ󥿥ץ꥿򼨤
Τˡ֥󥿥ץ꥿פȤۤɺץ
.I myecho
ȤץȤ롣

.in +4n
.nf
$ cat > script.sh
#! ./myecho script-arg
^D
$ chmod +x script.sh
.fi
.in

ƤץȤäƥץȤ¹Ԥ롣

.in +4n
.nf
$ ./execve ./script.sh
argv[0]: ./myecho
argv[1]: script-arg
argv[2]: ./script.sh
argv[3]: hello
argv[4]: world
.fi
.in
.SH Ϣ
.BR chmod (2),
.BR fork (2),
.BR ptrace (2),
.BR execl (3),
.BR fexecve (3),
.BR getopt (3),
.BR environ (7),
.BR credentials (7),
.BR path_resolution (7),
.BR ld.so (8).