1 /* vi: set sw=4 ts=4: */
3 * setsid.c -- execute a command in a new session
4 * Rick Sladkey <jrs@world.std.com>
5 * In the public domain.
7 * 1999-02-22 Arkadiusz Mickiewicz <misiek@pld.ORG.PL>
8 * - added Native Language Support
10 * 2001-01-18 John Fremlin <vii@penguinpowered.com>
11 * - fork in case we are process group leader
16 //config:config SETSID
17 //config: bool "setsid"
20 //config: setsid runs a program in a new session
22 //applet:IF_SETSID(APPLET(setsid, BB_DIR_USR_BIN, BB_SUID_DROP))
24 //kbuild:lib-$(CONFIG_SETSID) += setsid.o
26 //usage:#define setsid_trivial_usage
27 //usage: "[-c] PROG ARGS"
28 //usage:#define setsid_full_usage "\n\n"
29 //usage: "Run PROG in a new session. PROG will have no controlling terminal\n"
30 //usage: "and will not be affected by keyboard signals (^C etc).\n"
31 //usage: "\n -c Set controlling terminal to stdin"
35 int setsid_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
36 int setsid_main(int argc UNUSED_PARAM, char **argv)
40 opt_complementary = "-1"; /* at least one arg */
41 opt = getopt32(argv, "+c"); /* +: stop on first non-opt */
44 /* setsid() is allowed only when we are not a process group leader.
45 * Otherwise our PID serves as PGID of some existing process group
46 * and cannot be used as PGID of a new process group.
48 * Example: setsid() below fails when run alone in interactive shell:
50 * because shell's child (setsid) is put in a new process group.
51 * But doesn't fail if shell is not interactive
52 * (and therefore doesn't create process groups for pipes),
53 * or if setsid is not the first process in the process group:
54 * $ true | setsid PROG
55 * or if setsid is executed in backquotes (`setsid PROG`)...
58 pid_t pid = fork_or_rexec(argv);
62 * we can waitpid(pid, &status, 0) and then even
63 * emulate exitcode, making the behavior consistent
64 * in both forked and non forked cases.
65 * However, the code is larger and upstream
66 * does not do such trick.
72 /* now there should be no error: */
77 /* -c: set (with stealing) controlling tty */
78 ioctl(0, TIOCSCTTY, 1);
81 BB_EXECVP_or_die(argv);