I used the strace tool to follow it. I touch a file named lastpipe just
contain:
shopt -s lastpipe
exit 142 | false
run command:
$ strace /bin/bash lastpipe
the output:
read(3, "shopt -s lastpipe\nexit 142 | fal"..., 80) = 35
lseek(3, 0, SEEK_SET) = 0
getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=4*1024}) = 0
fcntl(255, F_GETFD) = -1 EBADF (Bad file
descriptor)
dup2(3, 255) = 255
close(3) = 0
fcntl(255, F_SETFD, FD_CLOEXEC) = 0
fcntl(255, F_GETFL) = 0x8000 (flags
O_RDONLY|O_LARGEFILE)
fstat(255, {st_mode=S_IFREG|0644, st_size=35, ...}) = 0
lseek(255, 0, SEEK_CUR) = 0
read(255, "shopt -s lastpipe\nexit 142 | fal"..., 35) = 35
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
pipe([3, 4]) = 0
rt_sigprocmask(SIG_BLOCK, [INT CHLD], [CHLD], 8) = 0
clone(child_stack=0,
flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD,
child_tidptr=0x7fc40e9fb9d0) = 774
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
close(4) = 0
close(4) = -1 EBADF (Bad file
descriptor)
getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=4*1024}) = 0
fcntl(255, F_GETFD) = 0x1 (flags FD_CLOEXEC)
fcntl(254, F_GETFD) = -1 EBADF (Bad file
descriptor)
dup2(0, 254) = 254
close(0) = 0
dup2(3, 0) = 0
close(3) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [CHLD], 8) = 0
rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
dup2(254, 0) = 0
close(254) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=774,
si_uid=0, si_status=142, si_utime=0, si_stime=0} ---
wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 142}], WNOHANG, NULL)
= 774
wait4(-1, 0x7ffc0efc1658, WNOHANG, NULL) = -1 ECHILD (No child
processes)
rt_sigreturn({mask=[]}) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGINT, {0x440490, [], SA_RESTORER, 0x7fc40e04b100},
{SIG_DFL, [], SA_RESTORER, 0x7fc40e04b100}, 8) = 0
rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7fc40e04b100},
{0x440490, [], SA_RESTORER, 0x7fc40e04b100}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
fstat(2, {st_mode=S_IFCHR|0600, st_rdev=makedev(4, 64), ...}) = 0
ioctl(2, TCGETS, {B115200 opost isig icanon echo ...}) = 0
write(2, "lastpipe: line 3: 774 Exit 142"..., 57lastpipe: line 3:
774 Exit 142 exit 142
) = 57
write(2, " 773 Hangup "..., 43 773
Hangup | false
) = 43
read(255, "", 35) = 0
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
exit_group(129) = ?
+++ exited with 129 +++
On 2016年08月10日 19:16, Chet Ramey wrote:
On 8/10/16 3:32 AM, dengke...@windriver.com wrote:
Hi all
When I run the bash test lastpipe.tests, there were some errors occurred.
The code in lastpipe.tests:
shopt -s lastpipe
...
exit 142 | false
echo $? -- ${PIPESTATUS[@]}
The error output:
lastpipe.tests: line 41: 708 Exit 142 exit 142
703 Hangup | false
129 -- 142 129
I can't reproduce this. It looks system-specific; there shouldn't be
anything sending a SIGHUP to a simple command there.
