strace of "sleep 1 | sleep 2" being run from interactive bash 3.0


Synopsis:
get current signal mask
install default handlers for GHLD QUIT TERM
install common handler for HUP INT ILL TRAP ABRT FPE BUS SEGV SYS PIPE ALRM TERM XCPU XFSZ VTALRM USR1 USR2
ignore QUIT
install handler for INT
ignore TERM
install handler for INT
ignore TSTP TTOU TTIN
install handler for WINCH
get pid, ppid
block all signals
unblock all signals
get our pprocess group
    minidoc:
    Each process group is a member of a session and each process is a member
    of the session of which its process group is a member.
    Process groups are used for distribution of signals, and by terminals
    to arbitrate requests for their input: processes that have the same
    process group as the terminal are foreground and may read, while others
    will block with a signal if they attempt to read.  These calls are thus used
    by programs (shells) to create process groups in implementing job control.
    The TIOCGPGRP and TIOCSPGRP calls described in termios(3) are used to get/set
    the process group of the control terminal.
    If a session has a controlling terminal, CLOCAL is not set and a hangup occurs,
    then the session leader is sent a SIGHUP.  If the session leader exits,
    the SIGHUP signal will be sent to each process in the foreground process
    group of the controlling terminal.
    If the exit of the process causes a process group to become orphaned,
    and if any member of the newly-orphaned process group is stopped, then a SIGHUP
    signal followed by a SIGCONT signal will be sent to each process
    in the newly-orphaned process group.
...



execve("/bin/sh", ["sh"], [/* 34 vars */]) = 0
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_DFL}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGTERM, {SIG_DFL}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGHUP, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGINT, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGILL, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGTRAP, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGABRT, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGFPE, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGBUS, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGSEGV, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGSYS, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGPIPE, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGALRM, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGTERM, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGXCPU, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGXFSZ, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGVTALRM, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGUSR1, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGUSR2, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTERM, {SIG_IGN}, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTSTP, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGTTIN, {SIG_IGN}, {SIG_DFL}, 8) = 0
rt_sigaction(SIGWINCH, {0x807dc33, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
getpid()                = 19473
getppid()               = 19472
rt_sigprocmask(SIG_BLOCK, ~[], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
getpgrp()               = 1865
dup(2)                  = 4
fcntl64(255, F_GETFD)   = -1 EBADF (Bad file descriptor)
dup2(4, 255)            = 255
close(4)                = 0
ioctl(255, TIOCGPGRP, [1865]) = 0
getpid()                = 19473
setpgid(0, 19473)       = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [], 8) = 0
ioctl(255, TIOCSPGRP, [19473]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
fcntl64(255, F_SETFD, FD_CLOEXEC) = 0
rt_sigaction(SIGCHLD, {0x807c922, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_DFL}, 8) = 0
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
fcntl64(0, F_GETFL)     = 0x2 (flags O_RDWR)
...
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [], 8) = 0
ioctl(255, TIOCSPGRP, [19473]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [INT], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGINT, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTERM, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTERM, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGQUIT, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGALRM, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTSTP, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTSTP, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTTOU, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTTIN, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTIN, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGWINCH, {0x80ca5cd, [], SA_RESTORER|SA_RESTART, 0x6ff7a4f8}, {0x807dc33, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, ~[], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
write(2, "sh-3.00# ", 9) = 9
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
read(0, "s", 1)         = 1
write(2, "s", 1)        = 1
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
read(0, "l", 1)         = 1
write(2, "l", 1)        = 1
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
... rest of "sleep 1 | sleep 2" entered...
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
read(0, "2", 1)         = 1
write(2, "2", 1)        = 1
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
read(0, "\r", 1)        = 1
write(2, "\n", 1)       = 1
rt_sigprocmask(SIG_BLOCK, [INT], [], 8) = 0
ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 opost isig icanon echo ...}) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTERM, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGALRM, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTSTP, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTIN, {SIG_IGN}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGWINCH, {0x807dc33, [], SA_RESTORER, 0x6ff7a4f8}, {0x80ca5cd, [], SA_RESTORER|SA_RESTART, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
pipe([4, 5])            = 0
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [CHLD], 8) = 0
fork()                  = 19755
setpgid(19755, 19755)                = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
close(5)                = 0
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [CHLD], 8) = 0
fork()                  = 19756
setpgid(19756, 19755)   = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
close(4)                = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [CHLD], 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [CHLD], 8) = 0
ioctl(255, TIOCSPGRP, [19755]) = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [CHLD], 8) = 0
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WUNTRACED, NULL) = 19755
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WUNTRACED, NULL) = 19756
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [CHLD], 8) = 0
ioctl(255, TIOCSPGRP, [19473]) = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
--- SIGCHLD (Child exited) @ 0 (0) ---
wait4(-1, 0x77fc9c54, WNOHANG|WUNTRACED, NULL) = -1 ECHILD (No child processes)
sigreturn()             = ? (mask now [])
rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [], 8) = 0
ioctl(255, TIOCSPGRP, [19473]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGINT, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigprocmask(SIG_BLOCK, [INT], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGINT, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTERM, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTERM, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGQUIT, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGALRM, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {0x808f752, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTSTP, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTSTP, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTTOU, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGTTIN, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTIN, {SIG_IGN}, {0x80ca530, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGWINCH, {0x80ca5cd, [], SA_RESTORER|SA_RESTART, 0x6ff7a4f8}, {0x807dc33, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
write(2, "sh-3.00# ", 9) = 9


getpid() = 19755
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGTSTP, {SIG_DFL}, {SIG_IGN}, 8)    = 0
rt_sigaction(SIGTTIN, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_DFL}, {SIG_IGN}, 8) = 0
setpgid(19755, 19755) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [], 8) = 0
ioctl(255, TIOCSPGRP, [19755]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
close(4)   = 0
dup2(5, 1) = 1
close(5)              = 0
rt_sigaction(SIGINT, {SIG_DFL}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTERM, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {0x807c922, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
execve("/bin/sleep", ["sleep", "1"], [/* 34 vars */]) = 0
...
_exit(0)                = ?


getpid() = 19756
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
rt_sigaction(SIGTSTP, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTIN, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTTOU, {SIG_DFL}, {SIG_IGN}, 8) = 0
setpgid(19756, 19755) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [], 8) = 0
ioctl(255, TIOCSPGRP, [19755]) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
dup2(4, 0) = 0
close(4) = 0
rt_sigaction(SIGINT, {SIG_DFL}, {0x808f7d7, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
rt_sigaction(SIGQUIT, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGTERM, {SIG_DFL}, {SIG_IGN}, 8) = 0
rt_sigaction(SIGCHLD, {SIG_DFL}, {0x807c922, [], SA_RESTORER, 0x6ff7a4f8}, 8) = 0
execve("/bin/sleep", ["sleep", "2"], [/* 34 vars */]) = 0
...
_exit(0)                = ?