Control: found -1 1:3.3.4-2 Hi,
The bug in #732410 may be just that ps argues about getting a CONT signal without being suspended. The following has been posted on the zsh workers' mailing list today[1]. [1] http://www.zsh.org/cgi-bin/mla/redirect?WORKERNUMBER=32251 Additionally, I was also able to reproduce it on an amrhf Jessie installation with procps 1:3.3.4-2 being installed: !514 Z1 ?0 L2 screen abe@c33:~ (pts/0 zsh 5.0.5 jessie) 22:01:16 ~ → echo `ps | cat` Signal 18 (CONT) caught by ps (procps-ng version 3.3.4). ps:display.c:59: please report this bug PID TTY TIME CMD 24893 pts/0 00:00:01 zsh 25183 pts/0 00:00:03 zsh 25294 pts/0 00:00:00 zsh 25295 pts/0 00:00:00 ps 25296 pts/0 00:00:00 cat !515 Z2 ?0 L2 screen abe@c33:~ (pts/0 zsh 5.0.5 jessie) 22:01:30 ~ → ----- Forwarded message from Bart Schaefer <[email protected]> ----- X-Seq: 32251 From: Bart Schaefer <[email protected]> Message-id: <[email protected]> Date: Sun, 12 Jan 2014 20:00:02 -0800 In-reply-to: <[email protected]> Comments: In reply to Michele Guerini Rocco <[email protected]> "Signal 18 (CONT) caught by ps (procps-ng version 3.3.9)" (Jan 12, 10:59pm) References: <[email protected]> To: Michele Guerini Rocco <[email protected]>, [email protected] Subject: Re: Signal 18 (CONT) caught by ps (procps-ng version 3.3.9) On Jan 12, 10:59pm, Michele Guerini Rocco wrote: } } Executing `ps -ef | wc -l` in a zsh shell script or directly with `echo $(ps -ef | wc -l)` will cause this message to appear: } } Signal 18 (CONT) caught by ps (procps-ng version 3.3.9). } ps:display.c:66: please report this bug``` That's rather a strange error message. Why would it be a bug for ps to get a CONT signal? There are cases in which zsh sends a CONT signal to a child process that *could* be in a stopped state without bothering to check first whether the child actually *is* stopped. This should be a completely harmless no-op for a child that's already running, and I'd say it's more a bug in ps for complaining about it than it is a bug in zsh for sending it. The "extraneous" SIGCONT is at line 285 of Src/jobs.c and "git blame" says it has been there since 2000-04-01, so there is undoubtedly *some* way to induce it in any version of zsh you're likely to be able to try; but the circumstances in which that code is called have changed recently, as we now try to do a more thorough job of tracking child processes for correct population the $pipestatus array and avoiding race conditions. Relevant strace: % schaefer[602] strace -q -f -e trace=kill,process Src/zsh -fc 'echo "$(ps -ef | wc -l)"' execve("Src/zsh", ["Src/zsh", "-fc", "echo \"$(ps -ef | wc -l)\""], [/* 34 vars */]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7eef708) = 9550 [pid 9550] clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7eef708) = 9551 [pid 9550] clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7eef708) = 9552 [pid 9551] execve("/bin/ps", ["ps", "-ef"], [/* 34 vars */] <unfinished ...> [pid 9552] execve("/usr/bin/wc", ["wc", "-l"], [/* 34 vars */] <unfinished ...> [pid 9551] <... execve resumed> ) = 0 [pid 9552] <... execve resumed> ) = 0 [pid 9551] exit_group(0) = ? [pid 9550] --- SIGCHLD (Child exited) @ 0 (0) --- [pid 9550] wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WNOHANG|WSTOPPED|WCONTINUED, {ru_utime={0, 9998}, ru_stime={0, 0}, ...}) = 9551 [pid 9550] wait4(-1, 0xbfeef6c4, WNOHANG|WSTOPPED|WCONTINUED, 0xbfeef64c) = 0 [pid 9550] kill(9551, SIGCONT <unfinished ...> [pid 9552] exit_group(0) = ? [pid 9550] <... kill resumed> ) = -1 ESRCH (No such process) [pid 9550] kill(9552, SIGCONT) = 0 [pid 9550] --- SIGCHLD (Child exited) @ 0 (0) --- [pid 9550] wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WNOHANG|WSTOPPED|WCONTINUED, {ru_utime={0, 0}, ru_stime={0, 9998}, ...}) = 9552 [pid 9550] wait4(-1, 0xbfeef6c4, WNOHANG|WSTOPPED|WCONTINUED, 0xbfeef64c) = -1 ECHILD (No child processes) [pid 9550] exit_group(0) = ? kill(9550, SIG_0) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WNOHANG|WSTOPPED|WCONTINUED, {ru_utime={0, 9998}, ru_stime={0, 9998}, ...}) = 9550 wait4(-1, 0xbfeefb24, WNOHANG|WSTOPPED|WCONTINUED, 0xbfeefaac) = -1 ECHILD (No child processes) kill(9550, SIG_0) = -1 ESRCH (No such process) 128 exit_group(0) = ? -- Barton E. Schaefer ----- End forwarded message ----- HTH. Regards, Axel -- ,''`. | Axel Beckert <[email protected]>, http://people.debian.org/~abe/ : :' : | Debian Developer, ftp.ch.debian.org Admin `. `' | 1024D: F067 EA27 26B9 C3FC 1486 202E C09E 1D89 9593 0EDE `- | 4096R: 2517 B724 C5F6 CA99 5329 6E61 2FF9 CD59 6126 16B5 -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
