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    Contents of /trunk/mkinitrd-magellan/busybox/shell/ash_doc.txt

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    Revision 984 - (show annotations) (download)
    Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
    File MIME type: text/plain
    File size: 4320 byte(s) 
    -updated to busybox-1.16.1 and enabled blkid/uuid support in default config
    1 Wait + signals
    2
    3 We had some bugs here which are hard to test in testsuite.
    4
    5 Bug 1280 (http://busybox.net/bugs/view.php?id=1280):
    6 was misbehaving in interactive ash. Correct behavior:
    7
    8 $ sleep 20 &
    9 $ wait
    10 ^C
    11 $ wait
    12 ^C
    13 $ wait
    14 ^C
    15 ...
    16
    17
    18 Bug 1984 (http://busybox.net/bugs/view.php?id=1984):
    19 traps were not triggering:
    20
    21 trap_handler_usr () {
    22 echo trap usr
    23 }
    24 trap_handler_int () {
    25 echo trap int
    26 }
    27 trap trap_handler_usr USR1
    28 trap trap_handler_int INT
    29 sleep 3600 &
    30 echo "Please do: kill -USR1 $$"
    31 echo "or: kill -INT $$"
    32 while true; do wait; echo wait interrupted; done
    33
    34
    35 Bug 189 (https://bugs.busybox.net/show_bug.cgi?id=189)
    36
    37 func() {
    38 sleep 1
    39 }
    40 while (true); do
    41 func
    42 echo Looping
    43 done
    44
    45 ^C was observed to make ash processes geometrically multiply (!) instead
    46 of exiting. (true) in subshell does not seem to matter, as another user
    47 reports the same with:
    48
    49 trap "echo USR1" USR1
    50 while true; do
    51 echo Sleeping
    52 sleep 5
    53 done
    54
    55 Compat note.
    56 Bash version 3.2.0(1) exits this script at the receipt of SIGINT
    57 _only_ if it had two last children die from it.
    58 The following trace was obtained while periodically running
    59 "killall -SIGINT sleep; sleep 0.1; kill -SIGINT <bash_PID>":
    60
    61 23:48:32.376707 clone(...) = 13528
    62 23:48:32.388706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
    63 23:48:32.459761 --- SIGINT (Interrupt) @ 0 (0) ---
    64 kill -SIGINT <bash_PID> is ignored, back to waiting:
    65 23:48:32.463706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13528
    66 sleep exited with 0
    67 23:48:37.377557 --- SIGCHLD (Child exited) @ 0 (0) ---
    68 23:48:37.378451 clone(...) = 13538
    69 23:48:37.390708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13538
    70 sleep was killed by "killall -SIGINT sleep"
    71 23:48:38.523944 --- SIGCHLD (Child exited) @ 0 (0) ---
    72 23:48:38.524861 clone(...) = 13542
    73 23:48:38.538706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
    74 23:48:38.624761 --- SIGINT (Interrupt) @ 0 (0) ---
    75 kill -SIGINT <bash_PID> is ignored, back to waiting:
    76 23:48:38.628706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13542
    77 sleep exited with 0
    78 23:48:43.525674 --- SIGCHLD (Child exited) @ 0 (0) ---
    79 23:48:43.526563 clone(...) = 13545
    80 23:48:43.538709 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13545
    81 sleep was killed by "killall -SIGINT sleep"
    82 23:48:44.466848 --- SIGCHLD (Child exited) @ 0 (0) ---
    83 23:48:44.467735 clone(...) = 13549
    84 23:48:44.481706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
    85 23:48:44.567757 --- SIGINT (Interrupt) @ 0 (0) ---
    86 kill -SIGINT <bash_PID> is ignored, back to waiting:
    87 23:48:44.571706 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 13549
    88 sleep exited with 0
    89 23:48:49.468553 --- SIGCHLD (Child exited) @ 0 (0) ---
    90 23:48:49.469445 clone(...) = 13551
    91 23:48:49.481708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13551
    92 sleep was killed by "killall -SIGINT sleep"
    93 23:48:50.515837 --- SIGCHLD (Child exited) @ 0 (0) ---
    94 23:48:50.516718 clone(...) = 13555
    95 23:48:50.530706 waitpid(-1, 0xffc832ec, 0) = ? ERESTARTSYS (To be restarted)
    96 23:48:50.615761 --- SIGINT (Interrupt) @ 0 (0) ---
    97 kill -SIGINT <bash_PID> is ignored, back to waiting:
    98 23:48:50.619705 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 13555
    99 sleep was killed by "killall -SIGINT sleep".
    100 This is the second one in a row. Kill ourself:
    101 23:48:51.504604 kill(13515, SIGINT) = 0
    102 23:48:51.504689 --- SIGINT (Interrupt) @ 0 (0) ---
    103 23:48:51.504915 +++ killed by SIGINT +++
    104
    105 As long as there is at least one "sleep 5" which exited successfully
    106 (not killed by SIGINT), bash continues. This is not documented anywhere
    107 AFAIKS.
    108
    109 Why keyboard ^C acts differently?
    110
    111 00:08:07.655985 clone(...) = 14270
    112 00:08:07.669707 waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 14270
    113 00:08:12.656872 --- SIGCHLD (Child exited) @ 0 (0) ---
    114 00:08:12.657743 clone(...) = 14273
    115 00:08:12.671708 waitpid(-1, [{WIFSIGNALED(s) && WTERMSIG(s) == SIGINT}], 0) = 14273
    116 00:08:13.810778 --- SIGINT (Interrupt) @ 0 (0) ---
    117 00:08:13.818705 kill(14269, SIGINT) = 0
    118 00:08:13.820103 --- SIGINT (Interrupt) @ 0 (0) ---
    119 00:08:13.820925 +++ killed by SIGINT +++
    120
    121 Perhaps because at the moment bash got SIGINT it had no children?
    122 (it did not manage to spawn new sleep yet, see the trace)