.\" Copyright (c) 2007 by Michael Kerrisk <mtk.manpages@gmail.com>
.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
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.\" 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.
.\"
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.\" manual page may be incorrect or out-of-date.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.
.\"
.\" 2007-06-13 Creation
.\"
.\" Japanese Version Copyright (c) 2007 Akihiro MOTOKI all rights reserved.
.\" Translated 2007-10-25, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.66
.\" Updated 2008-08-04, Akihiro MOTOKI, LDP v3.05
.\"
.TH CREDENTIALS 7 2008-06-03 "Linux" "Linux Programmer's Manual"
.SH ̾
credentials \- ǧڤѤץμ̻
.SH 
.SS ץID (PID)
ƥץϡǤʤΰդʼ̻Ҥġ
μ̻Ҥ
.BR fork (2)
Ȥäƥץݤ˳Ƥ롣
ץ
.BR getpid (2)
ȤäƼʬ PID Ǥ롣
PID 
.I pid_t
ɽ
.RI ( pid_t

.I <sys/types.h>
Ƥ)

PID ϳƼΥƥॳǤΥƥॳ뤬Ѥץ
ꤹ뤿˻Ѥ롣ʲ󤲤:
.BR kill (2),
.BR ptrace (2),
.BR setpriority (2),
.\" .BR sched_rr_get_interval (2),
.\" .BR sched_getaffinity (2),
.\" .BR sched_setaffinity (2),
.\" .BR sched_getparam (2),
.\" .BR sched_setparam (2),
.\" .BR sched_setscheduler (2),
.\" .BR sched_getscheduler (2),
.BR setpgid (2),
.\" .BR getsid (2),
.BR setsid (2),
.BR sigqueue (2),
.BR waitpid (2).
.\" .BR waitid (2),
.\" .BR wait4 (2),

ץ PID 
.BR execve (2)
ѤǤ롣
.SS ƥץ ID (PPID)
ץοƥץ ID ϡ
.BR fork (2)
ȤäƤΥץץ򼨤
ץ
.BR getppid (2)
ȤäƼʬ PPID Ǥ롣
PPID 
.I pid_t
ɽ롣

ץ PPID 
.BR execve (2)
ѤǤ롣
.SS ץ롼 ID ȥå ID
ƥץϥå ID ȥץ롼 ID ġ
 ID Ϥɤ
.I pid_t
ɽ롣
ץϡ줾
.BR getsid (2),
.BR getpgrp (2)
ȤäƼʬΥå IDץ롼 ID Ǥ롣

.BR fork (2)
줿ҥץϿƥץΥå ID ȥץ롼 ID
Ѿ롣ץΥå ID ȥץ롼 ID 
.BR execve (2)
ѤǤ롣

åȥץ롼פγǰϡΥԤ
ͰƤ줿ΤǤ롣
ץ롼 (ˤϡ֥֡פȸƤФ뤳Ȥ⤢) ϡ
Ʊץ롼 ID ͭץνޤǤ롣
ϡĤΥޥɤ⤷ϥѥץ饤μ¹Ԥ˻Ȥץ
ФưĤΥץ롼פ
(㤨Сޥ "ls\ |\ wc" ¹Ԥ뤿ĤΥץ
Ʊץ롼פ֤)
°ץ롼פ
.BR setpgid (2)
ȤäǤ롣
ȤΥץ ID ץ롼 ID Ʊץϡ
Υ롼פΡ֥ץ롼ס꡼פǤ롣

åϡƱå ID ͭץνޤǤ롣
ĤΥץ롼פСƱå ID 
(ĤޤꡢĤΥץ롼פΥСƱå˽°
ˤꡢåȥץ롼פؤΥץؤǤ)
ʥåϥץ
.BR setsid (2)
ƤӽФȤǹԤ
.BR setsid (2)
ϡ
.BR setsid (2)
ƤӽФץ PID ƱͤΥå ID 
ʥå롣
åԤϡ֥å󡦥꡼פȸƤФ롣
.SS 桼 ID ȥ롼 ID
ƥץϡΥ桼 ID ȥ롼 ID ġ
桼 ID롼 ID ǡ줾
.IR uid_t ,
.I gid_t
ɽ (
.I <sys/types.h>
Ƥ)

Linux ǤϡƥץϰʲΤ褦ʼΥ桼 ID ȥ롼 ID ġ
.IP * 3
¥桼 ID ȼ¥롼 ID
 ID ˤץνͭԤꤵ롣
ץʬμ¥桼 ID¥롼 ID ˤϡ줾
.BR getuid (2),
.BR getgid (2)
Ѥ롣
.IP *
¸桼 ID ȼ¸롼 ID
 ID ϡå塼ͭꡢޥեʤɤ
ͭ꥽˥褦ȤݤˤΥץĤ
äƤ뤫򥫡ͥ뤬ȽꤹΤ˻Ѥ롣
ۤȤɤ Unix ƥǤϡ ID ϥեؤΥ
ĤȽˤѤ롣
ʤ顢Linux ǤϥեؤΥĤȽˤ
ҤΥե륷ƥ ID Ѥ롣
ץʬμ¸桼 ID¸롼 ID ˤϡ줾
.BR geteuid (2),
.BR getegid (2)
Ѥ롣
.IP *
¸ (saved) set-user-ID ¸ set-group-ID
 ID ϡset-user-ID  set-group-ID 줿ץˤơ
ץμ¹Իꤵ줿¸ ID Υԡ¸뤿
Ѥ
.RB ( execve (2)
)
set-user-ID ץϡ¸桼 ID ¥桼ID ¸ set-user-ID
δ֤ǹԤä褿ڤؤ뤳ȤǡøȤǤ롣
ڤؤ
.BR seteuid (2),
.BR setreuid (2),
.BR setresuid (2)
ƤӽФȤǼ¹ԤǤ롣
set-group-ID ץϡ
.BR setegid (2),
.BR setregid (2),
.BR setresgid (2)
ȤäƱͤΤȤǤ롣
ץʬ¸ set-user-ID¸ set-group-ID ˤϡ
.BR getresuid(2),
.BR getresgids (2)
򤽤줾Ѥ롣
.IP *
ե륷ƥࡦ桼 ID ȥե륷ƥࡦ롼 ID (Linux ͭ)
 ID ϡҤ롼 ID Ȥ߹碌ƻѤ졢
եؤΥηѤ롣ܺ٤
.BR path_resolution (7)
򻲾ȡ
ץμ¸ ID (桼 ID  롼 ID) ѹ뤿Ӥˡ
ͥϼưŪбե륷ƥ ID Ʊͤѹ롣
η̡ե륷ƥ ID ̾б¸ ID ƱͤȤʤꡢ
եΥΥåˡ Linux ¾ Unix ƥƱǤ롣
ե륷ƥ ID ϼ¸ ID Ȥϰۤʤͤˤ뤳ȤǤ
ѹ
.BR setfsuid (2)

.BR setfsgid (2)
ƤӽФƹԤ
.IP *
롼 ID
 ID ϡե¾ζͭ꥽ؤΥ˥Ĥ
å˻Ѥ롢ɲäΥ롼 ID νǤ롣
ͥ 2.6.4  Linux ǤϡĤΥץ
롼פΥСϺ 32 Ǥ롣
ͥ 2.6.4 ʹߤǤϡĤΥץ
롼פΥСϺ 65536 Ǥ롣
.I sysconf(_SC_NGROUPS_MAX)
ƤӽФȤǡץСȤʤ뤳ȤǤǽΤ
롼׿Τ뤳ȤǤ롣
.\" Since kernel 2.6.4, the limit is visible via the read-only file
.\" /proc/sys/kernel/ngroups_max.
.\" As at 2.6.22-rc2, this file is still read-only.
ץϡʬ롼 ID ν
.BR getgroups (2)
ǼǤ
.BR setgroups (2)
ǽѹǤ롣
.PP
.BR fork (2)
줿ҥץϿƥץΥ桼 ID ȥ롼 ID Ѿ롣
.BR execve (2)
δ֡ץμ¥桼/롼 ID 롼 ID ѤǤ롣
¸ ID ¸å ID ѹǽ
.RB ( execve (2)
Ƥ)

嵭Ūʳˤ⡢ץΥ桼 ID ¾͡ʾ̤Ѥ롣
.IP * 3
ʥĤȽ \(em
.BR kill (2)
ȡ
.IP *
ץΥ塼󥰴ϢΥѥ᡼ (nice ͡
ꥢ륿ࡦ塼󥰥ݥꥷͥ١CPU affinity
ͥ) ĤȽ
塼󥰴ϢΥѥ᡼ˤ
.BR setpriority (2),
.BR sched_setaffinity (2),
.BR sched_setscheduler (2),
.BR sched_setparam (2),
.BR ioprio_set (2)
Ѥ롣
.IP *
꥽¤Υå
.BR getrlimit (2)
ȡ
.IP *
ץǤ inotify 󥹥󥹿ξ¤Υå
.BR inotify (7)
ȡ
.SH 
ץ IDƥץ IDץ롼 IDå ID 
POSIX.1-2001 ǵꤵƤ롣
 ID¸ ID¸å ID Υ桼 ID / 롼 ID 
롼 ID  POSIX.1-2001 ǵꤵƤ롣
ե륷ƥࡦ桼 ID / 롼 ID  Linux ˤĥǤ롣
.SH 
POSIX ΥåɻͤǤϡμ̻Ҥץåɤ
ͭ뤳ȤƤ롣
ʤ顢ͥΥ٥ǤϡLinux ϥå̡
桼ȥ롼פ˴ؤ뼱̻ҤƤ롣
NPTL åɼ(㤨
.BR setuid (2),
.BR setresuid (2)
ʤɤθƤӽФˤ) 桼䥰롼פ˴ؤ뼱̻ҤФѹ
ץƤ POSIX åɤФȿǤ뤳Ȥݾڤ
νԤäƤ롣
.SH Ϣ
.BR bash (1),
.BR csh (1),
.BR ps (1),
.BR access (2),
.BR execve (2),
.BR faccessat (2),
.BR fork (2),
.BR getpgrp (2),
.BR getpid (2),
.BR getppid (2),
.BR getsid (2),
.BR kill (2),
.BR killpg (2),
.BR setegid (2),
.BR seteuid (2),
.BR setfsgid (2),
.BR setfsuid (2),
.BR setgid (2),
.BR setgroups (2),
.BR setresgid (2),
.BR setresuid (2),
.BR setuid (2),
.BR waitpid (2),
.BR euidaccess (3),
.BR initgroups (3),
.BR tcgetpgrp (3),
.BR tcsetpgrp (3),
.BR capabilities (7),
.BR path_resolution (7),
.BR unix (7)