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• Perl, waitpid() exit code returning wrong value?

  - by Mike

  Consder this trivial example of fork()ing then waiting for a child to die in Perl #!/usr/bin/perl use strict; use warnings; if (fork() == 0) { exit(1); } waitpid(-1,0); print $?; $perl test.pl 256 I suspect the values of are being shifted upwards because when I do exit(2) in the child, the output becomes 512 I can't seem to find this documented in perl's waitpid. Is this a bug on my system or am I doing something wrong? (btw, my OS is solaris 10)

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• Does waitpid yield valid status information for a child process that has already exited?

  - by dtrebbien

  If I fork a child process, and the child process exits before the parent even calls waitpid, then is the exit status information that is set by waitpid still valid? If so, when does it become not valid; i.e., how do I ensure that I can call waitpid on the child pid and continue to get valid exit status information after an arbitrary amount of time, and how do I "clean up" (tell the OS that I am no longer interested in the exit status information for the finished child process)? I was playing around with the following code, and it appears that the exit status information is valid for at least a few seconds after the child finishes, but I do not know for how long or how to inform the OS that I won't be calling waitpid again: #include <assert.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/wait.h> int main() { pid_t pid = fork(); if (pid < 0) { fprintf(stderr, "Failed to fork\n"); return EXIT_FAILURE; } else if (pid == 0) { // code for child process _exit(17); } else { // code for parent sleep(3); int status; waitpid(pid, &status, 0); waitpid(pid, &status, 0); // call `waitpid` again just to see if the first call had an effect assert(WIFEXITED(status)); assert(WEXITSTATUS(status) == 17); } return EXIT_SUCCESS; }

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• determine pid of terminated process

  - by Hristo

  I'm trying to figure out what the pid is of a process that sent the SIGCHLD signal, and I want to do this in a signal handler I created for SIGCHLD. How would I do this? I'm trying: int pid = waitpid(-1, NULL, WNOHANG); .. because I want to wait for any child process that is spawned. Thanks, Hristo

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• Variable modification in a child process

  - by teaLeef

  I am working on Bryant and O'Hallaron's Computer Systems, A Programmer's Perspective. Exercise 8.16 asks for the output of a program like (I changed it because they use a header file you can download on their website): #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> #include <unistd.h> #include <string.h> int counter = 1; int main() { if (fork() == 0){ counter--; exit(0); } else{ Wait(NULL); printf("counter = %d\n", ++counter); } exit(0); } I answered "counter = 1" because the parent process waits for its children to terminate and then increments counter. But the child first decrements it. However, when I tested the program, I found that the correct answer was "counter = 2". Is the variable "counter" different in the child and in the parent process? If not, then why is the answer 2?

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• First could access the repository next cannot

  - by Banani

  Hi! I have configured svnserve (1.6.5,plain, without apache) on Fedora 12. I could ran the following svn subcommands which access the repository after configuration. Such as, commit, update,checkout, list. But, when next time ( after stopping,ctrl-c and then starting svnserve)I tried above commands, could not access the repository. This is happening both from local and remote machine. I ran svn and svnserve as below. 'svn commit svn://127.0.0.1/myrepository/' from local client. 'svnserve -d --foregorund --listen-port=3690 -r /path-to-repository/mypository/' To understand the problem better, I created another repository and found similar behavior . Frist I could access the repository and next I could not. I tried doing strace on svnserve, but don't uderstand much of it. Below is the partial output. accept(3, {sa_family=AF_INET, sin_port=htons(54425), sin_addr=inet_addr("127.0.0 .1")}, [16]) = 4 fcntl64(4, F_GETFD) = 0 fcntl64(4, F_SETFD, FD_CLOEXEC) = 0 waitpid(-1, 0xbfcdf31c, WNOHANG|WSTOPPED) = -1 ECHILD (No child processes) clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, chil d_tidptr=0xb7743758) = 9737 close(4) = 0 accept(3, 0xbfcdf2bc, [128]) = ? ERESTARTSYS (To be restarted) --- SIGCHLD (Child exited) @ 0 (0) --- sigreturn() = ? (mask now []) waitpid(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], WNOHANG|WSTOPPED) = 9737 waitpid(-1, 0xbfcdf31c, WNOHANG|WSTOPPED) = -1 ECHILD (No child processes) My question: Why user are not able to access the repository anymore? What information the strace output gives about this problem? Any help is much appreciated. Thanks. Banani

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• How to handle inputs in a C shell program during exec

  - by hits_lucky

  I am currently writing my own shell program. This simple shell can just execute commands. When executing commands like vi or calc which require input from the terminal , the command is getting executed and is waiting for the input from the user. But I am unable to give any input on the screen. How should the input be handled during the fork and exec. Here is the piece of code which is executing commands: if((pid = fork()) < 0) { perror("Fork failed"); exit(errno); } if(pid == 0) { // Child process if(execvp(arguments[0], arguments) == -1) { child_status = errno; switch(child_status) { case ENOENT: printf(" command not found \n"); break; } exit(errno); } } else { // parent process int wait_stat; if(waitpid(pid , &wait_stat, WNOHANG) == -1) { printf(" waitpid failed \n"); return; } } } ~ Thanks,

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• Rails 3 passenger nginx application spawner server error on Synology NAS

  - by peresleguine

  Question updated, please read UPD2. I'm trying to deploy app through passenger nginx module on DS710+ (ruby 1.9.2p0 installed). There is syntax error relative to has_and_belongs_to_many_association.rb file. Please look at the screenshot(deleted, question updated). I'm pretty sure the problem isn't in library file. App is running good via webrick. Could you please advise what to look for? UPD1 ruby -v ruby 1.9.2p0 (2010-08-18 revision 29036) [i686-linux] gem list -d passenger *** LOCAL GEMS *** passenger (3.0.6) Author: Phusion - http://www.phusion.nl/ Rubyforge: http://rubyforge.org/projects/passenger Homepage: http://www.modrails.com/ Installed at: /usr/lib/ruby/gems/1.9.1 Easy and robust Ruby web application deployment UPD2 I've decided to reinstall everything. It solved previous problem but caused another one. The error is: The application spawner server exited unexpectedly: Unexpected end-of-file detected. Here is screenshot. New output: ruby -v ruby 1.9.2p180 (2011-02-18 revision 30909) [x86_64-linux] gem list -d passenger *** LOCAL GEMS *** passenger (3.0.7) Author: Phusion - http://www.phusion.nl/ Rubyforge: http://rubyforge.org/projects/passenger Homepage: http://www.modrails.com/ Installed at: /usr/lib/ruby/gems/1.9.1 Nginx error.log: [ pid=5653 thr=32771 file=ext/common/Watchdog.cpp:128 time=2011-04-20 14:08:34.505 ]: waitpid() on Phusion Passenger helper agent return -1 with errno = ECHILD, falling back to kill polling [ pid=5654 thr=49156 file=ext/common/Watchdog.cpp:128 time=2011-04-20 14:08:34.506 ]: waitpid() on Phusion Passenger logging agent return -1 with errno = ECHILD, falling back to kill polling 2011/04/20 14:12:33 [notice] 7614#0: signal process started

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• how to debug when xinetd says : got signal 17 (child exited)

  - by Faizan Shaik

  I am trying to start services vsftpd and sshd using xinetd. my config files are as follows. /etc/xinetd.conf defaults { instances = 60 log_type = FILE /var/log/xinetdlog log_on_success = HOST PID log_on_failure = HOST cps = 25 30 only_from = localhost } includedir /etc/xinetd.d /etc/xinetd.d/ftp service ftp { disable = no server = /usr/sbin/vsftpd server_args = -l user = root socket_type = stream protocol = tcp wait = no instances = 4 flags = REUSE nice = 10 log_on_success += DURATION HOST USERID only_from = 127.0.0.1 10.0.0.0/24 } /etc/xinetd.d/ssh service ssh { disable = no log_on_failure += USERID server = /usr/sbin/sshd user = root socket_type = stream protocol = tcp wait = no instances = 20 flags = REUSE only_from = 127.0.0.1 10.0.0.0/24 } Even though i've included only_from attribute, vsftp server as well as ssh server are refusing connection from localhost. while vsftp and ssh servers are working fine individually when i check with "service vsftpd start" and "service ssh start". when i did debug using "xinetd -d" throug terminal i got the output as 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} Started service: ftp 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} Started service: ssh 13/10/20@00:06:08: DEBUG: 3592 {cnf_start_services} mask_max = 8, services_started = 2 13/10/20@00:06:08: NOTICE: 3592 {main} xinetd Version 2.3.14 started with libwrap loadavg options compiled in. 13/10/20@00:06:08: NOTICE: 3592 {main} Started working: 2 available services 13/10/20@00:06:08: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3592 {main_loop} select returned 1 13/10/20@00:06:16: DEBUG: 3592 {server_start} Starting service ftp 13/10/20@00:06:16: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3607 {exec_server} duping 9 13/10/20@00:06:16: DEBUG: 3592 {main_loop} active_services = 2 13/10/20@00:06:16: DEBUG: 3592 {main_loop} select returned 1 13/10/20@00:06:16: DEBUG: 3592 {check_pipe} Got signal 17 (Child exited) 13/10/20@00:06:16: DEBUG: 3592 {child_exit} waitpid returned = 3607 13/10/20@00:06:16: DEBUG: 3592 {server_end} ftp server 3607 exited 13/10/20@00:06:16: DEBUG: 3592 {svc_postmortem} Checking log size of ftp service 13/10/20@00:06:16: INFO: 3592 {conn_free} freeing connection 13/10/20@00:06:16: DEBUG: 3592 {child_exit} waitpid returned = -1 both services are getting started but neither of them is working. after banging for 3-4 hours i still don't have any clue about this error. Any help would be appreciated. thanks!

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• Perl kill(0, $pid) in Windows always returning 1

  - by banshee_walk_sly

  I'm trying to make a Perl script that will run a set of other programs in Windows. I need to be able to capture the stdout, stderr, and exit code of the process, and I need to be able to see if a process exceeds it's allotted execution time. Right now, the pertinent part of my code looks like: ... $pid = open3($wtr, $stdout, $stderr, $command); if($time < 0){ waitpid($pid, 0); $return = $? >> 8; $death_sig = $? & 127; $core_dump = $? & 128; } else{ # Do timeout stuff, currently not working as planned print "pid: $pid\n"; my $elapsed = 0; #THIS LOOP ONLY TERMINATES WHEN $time > $elapsed ...? while(kill 0, $pid and $time > $elapsed){ Time::HiRes::usleep(1000); # sleep for milliseconds $elapsed += 1; $return = $? >> 8; $death_sig = $? & 127; $core_dump = $? & 128; } if($elapsed >= $time){ $status = "FAIL"; print $log "TIME LIMIT EXCEEDED\n"; } } #these lines are needed to grab the stdout and stderr in arrays so # I may reuse them in multiple logs if(fileno $stdout){ @stdout = <$stdout>; } if(fileno $stderr){ @stderr = <$stderr>; } ... Everything is working correctly if $time = -1 (no timeout is needed), but the system thinks that kill 0, $pid is always 1. This makes my loop run for the entirety of the time allowed. Some extra details just for clarity: This is being run on Windows. I know my process does terminate because I have get all the expected output. Perl version: This is perl, v5.10.1 built for MSWin32-x86-multi-thread (with 2 registered patches, see perl -V for more detail) Copyright 1987-2009, Larry Wall Binary build 1007 [291969] provided by ActiveState http://www.ActiveState.com Built Jan 26 2010 23:15:11 I appreciate your help :D For that future person who may have a similar issue I got the code to work, here is the modified code sections: $pid = open3($wtr, $stdout, $stderr, $command); close($wtr); if($time < 0){ waitpid($pid, 0); } else{ print "pid: $pid\n"; my $elapsed = 0; while(waitpid($pid, WNOHANG) <= 0 and $time > $elapsed){ Time::HiRes::usleep(1000); # sleep for milliseconds $elapsed += 1; } if($elapsed >= $time){ $status = "FAIL"; print $log "TIME LIMIT EXCEEDED\n"; } } $return = $? >> 8; $death_sig = $? & 127; $core_dump = $? & 128; if(fileno $stdout){ @stdout = <$stdout>; } if(fileno $stderr){ @stderr = <$stderr>; } close($stdout); close($stderr);

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• Problem with fork exec kill when redirecting output in perl

  - by Edu

  I created a script in perl to run programs with a timeout. If the program being executed takes longer then the timeout than the script kills this program and returns the message "TIMEOUT". The script worked quite well until I decided to redirect the output of the executed program. When the stdout and stderr are being redirected, the program executed by the script is not being killed because it has a pid different than the one I got from fork. It seems perl executes a shell that executes my program in the case of redirection. I would like to have the output redirection but still be able to kill the program in the case of a timeout. Any ideas on how I could do that? A simplified code of my script is: #!/usr/bin/perl use strict; use warnings; use POSIX ":sys_wait_h"; my $timeout = 5; my $cmd = "very_long_program 1>&2 > out.txt"; my $pid = fork(); if( $pid == 0 ) { exec($cmd) or print STDERR "Couldn't exec '$cmd': $!"; exit(2); } my $time = 0; my $kid = waitpid($pid, WNOHANG); while ( $kid == 0 ) { sleep(1); $time ++; $kid = waitpid($pid, WNOHANG); print "Waited $time sec, result $kid\n"; if ($timeout > 0 && $time > $timeout) { print "TIMEOUT!\n"; #Kill process kill 9, $pid; exit(3); } } if ( $kid == -1) { print "Process did not exist\n"; exit(4); } print "Process exited with return code $?\n"; exit($?); Thanks for any help.

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• Process is killed without a (obvious) reason and program stops working

  - by Krzysiek Gurniak

  Here's what my program is supposed to do: create 4 child processes: process 0 is reading 1 byte at a time from STDIN, then writing it into FIFO process 1 is reading this 1 byte from fifo and write its value as HEX into shared memory process 2 is reading HEX value from shared memory and writing it into pipe finally process 3 is reading from pipe and writing into STDOUT (in my case: terminal) I can't change communication channels. FIFO, then shared memory, then pipes are the only option. My problem: Program stops at random moments when some file is directed into stdin (for example:./program < /dev/urandom). Sometimes after writing 5 HEX values, sometimes after 100. Weird thing is that when it is working and in another terminal I write "pstree -c" there is 1 main process with 4 children processes (which is what I want), but when I write "pstree -c" after it stopped writing (but still runs) there are only 3 child processes. For some reason 1 is gone even though they all have while(1) in them.. I think I might have problem with synchronization here, but I am unable to spot it (I've tried for many hours). Here's the code: #include <unistd.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/shm.h> #include <sys/sem.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/stat.h> #include <string.h> #include <signal.h> #define BUFSIZE 1 #define R 0 #define W 1 // processes ID pid_t p0, p1, p2, p3; // FIFO variables int fifo_fd; unsigned char bufor[BUFSIZE] = {}; unsigned char bufor1[BUFSIZE] = {}; // Shared memory variables key_t key; int shmid; char * tab; // zmienne do pipes int file_des[2]; char bufor_pipe[BUFSIZE*30] = {}; void proces0() { ssize_t n; while(1) { fifo_fd = open("/tmp/fifo",O_WRONLY); if(fifo_fd == -1) { perror("blad przy otwieraniu kolejki FIFO w p0\n"); exit(1); } n = read(STDIN_FILENO, bufor, BUFSIZE); if(n<0) { perror("read error w p0\n"); exit(1); } if(n > 0) { if(write(fifo_fd, bufor, n) != n) { perror("blad zapisu do kolejki fifo w p0\n"); exit(1); } memset(bufor, 0, n); // czyszczenie bufora } close(fifo_fd); } } void proces1() { ssize_t m, x; char wartosc_hex[30] = {}; while(1) { if(tab[0] == 0) { fifo_fd = open("/tmp/fifo", O_RDONLY); // otwiera plik typu fifo do odczytu if(fifo_fd == -1) { perror("blad przy otwieraniu kolejki FIFO w p1\n"); exit(1); } m = read(fifo_fd, bufor1, BUFSIZE); x = m; if(x < 0) { perror("read error p1\n"); exit(1); } if(x > 0) { // Konwersja na HEX if(bufor1[0] < 16) { if(bufor1[0] == 10) // gdy enter { sprintf(wartosc_hex, "0x0%X\n", bufor1[0]); } else { sprintf(wartosc_hex, "0x0%X ", bufor1[0]); } } else { sprintf(wartosc_hex, "0x%X ", bufor1[0]); } // poczekaj az pamiec bedzie pusta (gotowa do zapisu) strcpy(&tab[0], wartosc_hex); memset(bufor1, 0, sizeof(bufor1)); // czyszczenie bufora memset(wartosc_hex, 0, sizeof(wartosc_hex)); // przygotowanie tablicy na zapis wartosci hex x = 0; } close(fifo_fd); } } } void proces2() { close(file_des[0]); // zablokuj kanal do odczytu while(1) { if(tab[0] != 0) { if(write(file_des[1], tab, strlen(tab)) != strlen(tab)) { perror("blad write w p2"); exit(1); } // wyczysc pamiec dzielona by przyjac kolejny bajt memset(tab, 0, sizeof(tab)); } } } void proces3() { ssize_t n; close(file_des[1]); // zablokuj kanal do zapisu while(1) { if(tab[0] == 0) { if((n = read(file_des[0], bufor_pipe, sizeof(bufor_pipe))) > 0) { if(write(STDOUT_FILENO, bufor_pipe, n) != n) { perror("write error w proces3()"); exit(1); } memset(bufor_pipe, 0, sizeof(bufor_pipe)); } } } } int main(void) { key = 5678; int status; // Tworzenie plikow przechowujacych ID procesow int des_pid[2] = {}; char bufor_proces[50] = {}; mknod("pid0", S_IFREG | 0777, 0); mknod("pid1", S_IFREG | 0777, 0); mknod("pid2", S_IFREG | 0777, 0); mknod("pid3", S_IFREG | 0777, 0); // Tworzenie semaforow key_t klucz; klucz = ftok(".", 'a'); // na podstawie pliku i pojedynczego znaku id wyznacza klucz semafora if(klucz == -1) { perror("blad wyznaczania klucza semafora"); exit(1); } semafor = semget(klucz, 1, IPC_CREAT | 0777); // tworzy na podstawie klucza semafor. 1 - ilosc semaforow if(semafor == -1) { perror("blad przy tworzeniu semafora"); exit(1); } if(semctl(semafor, 0, SETVAL, 0) == -1) // ustawia poczatkowa wartosc semafora (klucz, numer w zbiorze od 0, polecenie, argument 0/1/2) { perror("blad przy ustawianiu wartosci poczatkowej semafora"); exit(1); } // Tworzenie lacza nazwanego FIFO if(access("/tmp/fifo", F_OK) == -1) // sprawdza czy plik istnieje, jesli nie - tworzy go { if(mkfifo("/tmp/fifo", 0777) != 0) { perror("blad tworzenia FIFO w main"); exit(1); } } // Tworzenie pamieci dzielonej // Lista pamieci wspoldzielonych, komenda "ipcs" // usuwanie pamieci wspoldzielonej, komenta "ipcrm -m ID_PAMIECI" shmid = shmget(key, (BUFSIZE*30), 0666 | IPC_CREAT); if(shmid == -1) { perror("shmget"); exit(1); } tab = (char *) shmat(shmid, NULL, 0); if(tab == (char *)(-1)) { perror("shmat"); exit(1); } memset(tab, 0, (BUFSIZE*30)); // Tworzenie lacza nienazwanego pipe if(pipe(file_des) == -1) { perror("pipe"); exit(1); } // Tworzenie procesow potomnych if(!(p0 = fork())) { des_pid[W] = open("pid0", O_WRONLY | O_TRUNC | O_CREAT); // 1 - zapis, 0 - odczyt sprintf(bufor_proces, "Proces0 ma ID: %d\n", getpid()); if(write(des_pid[W], bufor_proces, sizeof(bufor_proces)) != sizeof(bufor_proces)) { perror("blad przy zapisie pid do pliku w p0"); exit(1); } close(des_pid[W]); proces0(); } else if(p0 == -1) { perror("blad przy p0 fork w main"); exit(1); } else { if(!(p1 = fork())) { des_pid[W] = open("pid1", O_WRONLY | O_TRUNC | O_CREAT); // 1 - zapis, 0 - odczyt sprintf(bufor_proces, "Proces1 ma ID: %d\n", getpid()); if(write(des_pid[W], bufor_proces, sizeof(bufor_proces)) != sizeof(bufor_proces)) { perror("blad przy zapisie pid do pliku w p1"); exit(1); } close(des_pid[W]); proces1(); } else if(p1 == -1) { perror("blad przy p1 fork w main"); exit(1); } else { if(!(p2 = fork())) { des_pid[W] = open("pid2", O_WRONLY | O_TRUNC | O_CREAT); // 1 - zapis, 0 - odczyt sprintf(bufor_proces, "Proces2 ma ID: %d\n", getpid()); if(write(des_pid[W], bufor_proces, sizeof(bufor_proces)) != sizeof(bufor_proces)) { perror("blad przy zapisie pid do pliku w p2"); exit(1); } close(des_pid[W]); proces2(); } else if(p2 == -1) { perror("blad przy p2 fork w main"); exit(1); } else { if(!(p3 = fork())) { des_pid[W] = open("pid3", O_WRONLY | O_TRUNC | O_CREAT); // 1 - zapis, 0 - odczyt sprintf(bufor_proces, "Proces3 ma ID: %d\n", getpid()); if(write(des_pid[W], bufor_proces, sizeof(bufor_proces)) != sizeof(bufor_proces)) { perror("blad przy zapisie pid do pliku w p3"); exit(1); } close(des_pid[W]); proces3(); } else if(p3 == -1) { perror("blad przy p3 fork w main"); exit(1); } else { // proces macierzysty waitpid(p0, &status, 0); waitpid(p1, &status, 0); waitpid(p2, &status, 0); waitpid(p3, &status, 0); //wait(NULL); unlink("/tmp/fifo"); shmdt(tab); // odlaczenie pamieci dzielonej shmctl(shmid, IPC_RMID, NULL); // usuwanie pamieci wspoldzielonej printf("\nKONIEC PROGRAMU\n"); } } } } exit(0); }

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• Issues with signal handling [closed]

  - by user34790

  I am trying to actually study the signal handling behavior in multiprocess system. I have a system where there are three signal generating processes generating signals of type SIGUSR1 and SIGUSR1. I have two handler processes that handle a particular type of signal. I have another monitoring process that also receives the signals and then does its work. I have a certain issue. Whenever my signal handling processes generate a signal of a particular type, it is sent to the process group so it is received by the signal handling processes as well as the monitoring processes. Whenever the signal handlers of monitoring and signal handling processes are called, I have printed to indicate the signal handling. I was expecting a uniform series of calls for the signal handlers of the monitoring and handling processes. However, looking at the output I could see like at the beginning the monitoring and signal handling processes's signal handlers are called uniformly. However, after I could see like signal handler processes handlers being called in a burst followed by the signal handler of monitoring process being called in a burst. Here is my code and output #include <iostream> #include <sys/types.h> #include <sys/wait.h> #include <sys/time.h> #include <signal.h> #include <cstdio> #include <stdlib.h> #include <sys/ipc.h> #include <sys/shm.h> #define NUM_SENDER_PROCESSES 3 #define NUM_HANDLER_PROCESSES 4 #define NUM_SIGNAL_REPORT 10 #define MAX_SIGNAL_COUNT 100000 using namespace std; volatile int *usrsig1_handler_count; volatile int *usrsig2_handler_count; volatile int *usrsig1_sender_count; volatile int *usrsig2_sender_count; volatile int *lock_1; volatile int *lock_2; volatile int *lock_3; volatile int *lock_4; volatile int *lock_5; volatile int *lock_6; //Used only by the monitoring process volatile int monitor_count; volatile int usrsig1_monitor_count; volatile int usrsig2_monitor_count; double time_1[NUM_SIGNAL_REPORT]; double time_2[NUM_SIGNAL_REPORT]; //Used only by the main process int total_signal_count; //For shared memory int shmid; const int shareSize = sizeof(int) * (10); double timestamp() { struct timeval tp; gettimeofday(&tp, NULL); return (double)tp.tv_sec + tp.tv_usec / 1000000.; } pid_t senders[NUM_SENDER_PROCESSES]; pid_t handlers[NUM_HANDLER_PROCESSES]; pid_t reporter; void signal_catcher_1(int); void signal_catcher_2(int); void signal_catcher_int(int); void signal_catcher_monitor(int); void signal_catcher_main(int); void terminate_processes() { //Kill the child processes int status; cout << "Time up terminating the child processes" << endl; for(int i=0; i<NUM_SENDER_PROCESSES; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); //Wait for the child processes to finish for(int i=0; i<NUM_SENDER_PROCESSES; i++) { waitpid(senders[i], &status, 0); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { waitpid(handlers[i], &status, 0); } waitpid(reporter, &status, 0); } int main(int argc, char *argv[]) { if(argc != 2) { cout << "Required parameters missing. " << endl; cout << "Option 1 = 1 which means run for 30 seconds" << endl; cout << "Option 2 = 2 which means run until 100000 signals" << endl; exit(0); } int option = atoi(argv[1]); pid_t pid; if(option == 2) { if(signal(SIGUSR1, signal_catcher_main) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, signal_catcher_main) == SIG_ERR) { perror("2"); exit(1); } } else { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } } if(signal(SIGINT, signal_catcher_int) == SIG_ERR) { perror("3"); exit(1); } /////////////////////////////////////////////////////////////////////////////////////// ////////////////////// Initializing the shared memory ///////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////// cout << "Initializing the shared memory" << endl; if ((shmid=shmget(IPC_PRIVATE,shareSize,IPC_CREAT|0660))< 0) { perror("shmget fail"); exit(1); } usrsig1_handler_count = (int *) shmat(shmid, NULL, 0); usrsig2_handler_count = usrsig1_handler_count + 1; usrsig1_sender_count = usrsig2_handler_count + 1; usrsig2_sender_count = usrsig1_sender_count + 1; lock_1 = usrsig2_sender_count + 1; lock_2 = lock_1 + 1; lock_3 = lock_2 + 1; lock_4 = lock_3 + 1; lock_5 = lock_4 + 1; lock_6 = lock_5 + 1; //Initialize them to be zero *usrsig1_handler_count = 0; *usrsig2_handler_count = 0; *usrsig1_sender_count = 0; *usrsig2_sender_count = 0; *lock_1 = 0; *lock_2 = 0; *lock_3 = 0; *lock_4 = 0; *lock_5 = 0; *lock_6 = 0; cout << "End of initializing the shared memory" << endl; ///////////////////////////////////////////////////////////////////////////////////////////// /////////////////// End of initializing the shared memory /////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////////// /////////////////////////////Registering the signal handlers/////////////////////////////// /////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the signal handlers" << endl; for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { if((pid = fork()) == 0) { if(i%2 == 0) { struct sigaction action; action.sa_handler = signal_catcher_1; sigset_t block_mask; action.sa_flags = 0; sigaction(SIGUSR1,&action,NULL); if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } } else { if(signal(SIGUSR1 ,SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } struct sigaction action; action.sa_handler = signal_catcher_2; action.sa_flags = 0; sigaction(SIGUSR2,&action,NULL); } if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } while(true) { pause(); } exit(0); } else { //cout << "Registerd the handler " << pid << endl; handlers[i] = pid; } } cout << "End of registering the signal handlers" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////End of registering the signal handlers ////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////////////////////////// ///////////////////////////Registering the monitoring process ////////////////////////////////////// //////////////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the monitoring process" << endl; if((pid = fork()) == 0) { struct sigaction action; action.sa_handler = signal_catcher_monitor; sigemptyset(&action.sa_mask); sigset_t block_mask; sigemptyset(&block_mask); sigaddset(&block_mask,SIGUSR1); sigaddset(&block_mask,SIGUSR2); action.sa_flags = 0; action.sa_mask = block_mask; sigaction(SIGUSR1,&action,NULL); sigaction(SIGUSR2,&action,NULL); if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } while(true) { pause(); } exit(0); } else { cout << "Monitor's pid is " << pid << endl; reporter = pid; } cout << "End of registering the monitoring process" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////End of registering the monitoring process//////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //Sleep to make sure that the monitor and handler processes are well initialized and ready to handle signals sleep(5); ////////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////Registering the signal generators/////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// cout << "Registering the signal generators" << endl; for(int i=0; i<NUM_SENDER_PROCESSES; i++) { if((pid = fork()) == 0) { if(signal(SIGUSR1, SIG_IGN) == SIG_ERR) { perror("1"); exit(1); } if(signal(SIGUSR2, SIG_IGN) == SIG_ERR) { perror("2"); exit(1); } if(signal(SIGINT, SIG_DFL) == SIG_ERR) { perror("2"); exit(1); } srand(i); while(true) { int signal_id = rand()%2 + 1; if(signal_id == 1) { killpg(getpgid(getpid()), SIGUSR1); while(__sync_lock_test_and_set(lock_4,1) != 0) { } (*usrsig1_sender_count)++; *lock_4 = 0; } else { killpg(getpgid(getpid()), SIGUSR2); while(__sync_lock_test_and_set(lock_5,1) != 0) { } (*usrsig2_sender_count)++; *lock_5=0; } int r = rand()%10 + 1; double s = (double)r/100; sleep(s); } exit(0); } else { //cout << "Registered the sender " << pid << endl; senders[i] = pid; } } //cout << "End of registering the signal generators" << endl; ///////////////////////////////////////////////////////////////////////////////////////////////////// //////////////////////////End of registering the signal generators/////////////////////////////////// ///////////////////////////////////////////////////////////////////////////////////////////////////// //Either sleep for 30 seconds and terminate the program or if the number of signals generated reaches 10000, terminate the program if(option = 1) { sleep(90); terminate_processes(); } else { while(true) { if(total_signal_count >= MAX_SIGNAL_COUNT) { terminate_processes(); } else { sleep(0.001); } } } } void signal_catcher_1(int the_sig) { while(__sync_lock_test_and_set(lock_1,1) != 0) { } (*usrsig1_handler_count) = (*usrsig1_handler_count) + 1; cout << "Signal Handler 1 " << *usrsig1_handler_count << endl; __sync_lock_release(lock_1); } void signal_catcher_2(int the_sig) { while(__sync_lock_test_and_set(lock_2,1) != 0) { } (*usrsig2_handler_count) = (*usrsig2_handler_count) + 1; __sync_lock_release(lock_2); } void signal_catcher_main(int the_sig) { while(__sync_lock_test_and_set(lock_6,1) != 0) { } total_signal_count++; *lock_6 = 0; } void signal_catcher_int(int the_sig) { for(int i=0; i<NUM_SENDER_PROCESSES; i++) { kill(senders[i],SIGKILL); } for(int i=0; i<NUM_HANDLER_PROCESSES; i++) { kill(handlers[i],SIGKILL); } kill(reporter,SIGKILL); exit(3); } void signal_catcher_monitor(int the_sig) { cout << "Monitoring process " << *usrsig1_handler_count << endl; } Here is the initial segment of output Monitoring process 0 Monitoring process 0 Monitoring process 0 Monitoring process 0 Signal Handler 1 1 Monitoring process 2 Signal Handler 1 2 Signal Handler 1 3 Signal Handler 1 4 Monitoring process 4 Monitoring process Signal Handler 1 6 Signal Handler 1 7 Monitoring process 7 Monitoring process 8 Monitoring process 8 Signal Handler 1 9 Monitoring process 9 Monitoring process 9 Monitoring process 10 Signal Handler 1 11 Monitoring process 11 Monitoring process 12 Signal Handler 1 13 Signal Handler 1 14 Signal Handler 1 15 Signal Handler 1 16 Signal Handler 1 17 Signal Handler 1 18 Monitoring process 19 Signal Handler 1 20 Monitoring process 20 Signal Handler 1 21 Monitoring process 21 Monitoring process 21 Monitoring process 22 Monitoring process 22 Monitoring process 23 Signal Handler 1 24 Signal Handler 1 25 Monitoring process 25 Signal Handler 1 27 Signal Handler 1 28 Signal Handler 1 29 Here is the segment when the signal handler processes signal handlers are called in a burst Signal Handler 1 456 Signal Handler 1 457 Signal Handler 1 458 Signal Handler 1 459 Signal Handler 1 460 Signal Handler 1 461 Signal Handler 1 462 Signal Handler 1 463 Signal Handler 1 464 Signal Handler 1 465 Signal Handler 1 466 Signal Handler 1 467 Signal Handler 1 468 Signal Handler 1 469 Signal Handler 1 470 Signal Handler 1 471 Signal Handler 1 472 Signal Handler 1 473 Signal Handler 1 474 Signal Handler 1 475 Signal Handler 1 476 Signal Handler 1 477 Signal Handler 1 478 Signal Handler 1 479 Signal Handler 1 480 Signal Handler 1 481 Signal Handler 1 482 Signal Handler 1 483 Signal Handler 1 484 Signal Handler 1 485 Signal Handler 1 486 Signal Handler 1 487 Signal Handler 1 488 Signal Handler 1 489 Signal Handler 1 490 Signal Handler 1 491 Signal Handler 1 492 Signal Handler 1 493 Signal Handler 1 494 Signal Handler 1 495 Signal Handler 1 496 Signal Handler 1 497 Signal Handler 1 498 Signal Handler 1 499 Signal Handler 1 500 Signal Handler 1 501 Signal Handler 1 502 Signal Handler 1 503 Signal Handler 1 504 Signal Handler 1 505 Signal Handler 1 506 Here is the segment when the monitoring processes signal handlers are called in a burst Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Monitoring process 140 Why isn't it uniform afterwards. Why are they called in a burst?

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• How to remove the hint in the terminal?

  - by jiangchengwu

  As a normal user , when I run some command like ps\netstat, the terminal hint me: (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) I know could redirect STDERR to /dev/null can remove this hint. But I want to know is there any way to remove it , such as edit some configuration files ? [deploy@storage2 ~]$ ps -V (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) procps version 3.2.7 [deploy@storage2 ~]$ ps -V 2>/dev/null procps version 3.2.7 My OS info: [deploy@storage2 ~]$ uname -a Linux storage2 2.6.18-243.el5 #1 SMP Mon Feb 7 18:47:27 EST 2011 x86_64 x86_64 x86_64 GNU/Linux [deploy@storage2 ~]$ lsb_release LSB Version: :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch [deploy@storage2 ~]$ netstat -V (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) net-tools 1.60 netstat 1.42 (2001-04-15) Fred Baumgarten, Alan Cox, Bernd Eckenfels, Phil Blundell, Tuan Hoang and others +NEW_ADDRT +RTF_IRTT +RTF_REJECT +FW_MASQUERADE +I18N AF: (inet) +UNIX +INET +INET6 +IPX +AX25 +NETROM +X25 +ATALK +ECONET +ROSE HW: +ETHER +ARC +SLIP +PPP +TUNNEL +TR +AX25 +NETROM +X25 +FR +ROSE +ASH +SIT +FDDI +HIPPI +HDLC/LAPB There are more info from strace: [deploy@storage2 ~]$ strace ps -V execve("/bin/ps", ["ps", "-V"], [/* 27 vars */]) = 0 brk(0) = 0x929a000 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory) open("/etc/ld.so.cache", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=99752, ...}) = 0 mmap2(NULL, 99752, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7fde000 close(3) = 0 open("/lib/libnsl.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 \241\210\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=101404, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fdd000 mmap2(0x887000, 92104, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x887000 mmap2(0x89a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x12) = 0x89a000 mmap2(0x89c000, 6088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x89c000 close(3) = 0 open("/lib/libdl.so.2", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0Pzt\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=16428, ...}) = 0 mmap2(0x747000, 12408, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x747000 mmap2(0x749000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0x749000 close(3) = 0 open("/lib/libm.so.6", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\20\204p\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=208352, ...}) = 0 mmap2(0x705000, 155760, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x705000 mmap2(0x72a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x24) = 0x72a000 close(3) = 0 open("/lib/libcrypt.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340\246q\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=45288, ...}) = 0 mmap2(0x71a000, 201020, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7fab000 mmap2(0xf7fb4000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8) = 0xfffffffff7fb4000 mmap2(0xf7fb6000, 155964, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fb6000 close(3) = 0 open("/lib/libutil.so.1", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 \n\0\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=13420, ...}) = 0 mmap2(NULL, 12428, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7fa7000 mmap2(0xf7fa9000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xfffffffff7fa9000 close(3) = 0 open("/lib/libpthread.so.0", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@(s\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=129716, ...}) = 0 mmap2(0x72e000, 90596, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x72e000 mmap2(0x741000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0x741000 mmap2(0x743000, 4580, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x743000 close(3) = 0 open("/lib/libc.so.6", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\340?]\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=1611564, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fa6000 mmap2(0x5be000, 1328580, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x5be000 mmap2(0x6fd000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13f) = 0x6fd000 mmap2(0x700000, 9668, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x700000 close(3) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7fa5000 set_thread_area(0xffd61bb4) = 0 mprotect(0x6fd000, 8192, PROT_READ) = 0 mprotect(0x741000, 4096, PROT_READ) = 0 mprotect(0xf7fa9000, 4096, PROT_READ) = 0 mprotect(0xf7fb4000, 4096, PROT_READ) = 0 mprotect(0x72a000, 4096, PROT_READ) = 0 mprotect(0x749000, 4096, PROT_READ) = 0 mprotect(0x89a000, 4096, PROT_READ) = 0 mprotect(0x5ba000, 4096, PROT_READ) = 0 munmap(0xf7fde000, 99752) = 0 set_tid_address(0xf7fa5708) = 20214 set_robust_list(0xf7fa5710, 0xc) = 0 futex(0xffd61f74, FUTEX_WAKE_PRIVATE, 1) = 0 rt_sigaction(SIGRTMIN, {0x4007323d0, [], 0}, NULL, 8) = 0 rt_sigaction(SIGRT_1, {0x10000004007322e0, [], 0}, NULL, 8) = 0 rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0 getrlimit(RLIMIT_STACK, {rlim_cur=-4284481536, rlim_max=67108864*1024}) = 0 uname({sys="Linux", node="storage2", ...}) = 0 readlink("/proc/self/exe", "/bin/ps"..., 260) = 7 brk(0) = 0x929a000 brk(0x92bb000) = 0x92bb000 open("/bin/ps", O_RDONLY|O_LARGEFILE) = 3 _llseek(3, -12, [711660], SEEK_END) = 0 read(3, "\274U!\253\2\0\0\0\224\237\t\0", 12) = 12 mmap2(NULL, 634880, PROT_READ, MAP_SHARED, 3, 0x13) = 0xfffffffff7f0a000 mmap2(NULL, 630784, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7e70000 close(3) = 0 futex(0x74a06c, FUTEX_WAKE_PRIVATE, 2147483647) = 0 geteuid32() = 501 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 socket(PF_FILE, SOCK_STREAM, 0) = 3 fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0 connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"...}, 110) = -1 ENOENT (No such file or directory) close(3) = 0 open("/etc/nsswitch.conf", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=1696, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7ff6000 read(3, "#\n# /etc/nsswitch.conf\n#\n# An ex"..., 4096) = 1696 read(3, "", 4096) = 0 close(3) = 0 munmap(0xf7ff6000, 4096) = 0 open("/etc/ld.so.cache", O_RDONLY) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=99752, ...}) = 0 mmap2(NULL, 99752, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7fde000 close(3) = 0 open("/lib/libnss_files.so.2", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300\30\0\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0755, st_size=46680, ...}) = 0 mmap2(NULL, 41616, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7e65000 mmap2(0xf7e6e000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8) = 0xfffffffff7e6e000 close(3) = 0 mprotect(0xf7e6e000, 4096, PROT_READ) = 0 munmap(0xf7fde000, 99752) = 0 open("/etc/passwd", O_RDONLY) = 3 fcntl64(3, F_GETFD) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 fstat64(3, {st_mode=S_IFREG|0644, st_size=2166, ...}) = 0 mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7ff6000 read(3, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2166 close(3) = 0 munmap(0xf7ff6000, 4096) = 0 mkdir("/tmp/pdk-deploy/", 0755) = -1 EEXIST (File exists) mkdir("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a", 0755) = -1 EEXIST (File exists) open("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a/libperl.so", O_RDONLY|O_LARGEFILE) = 3 close(3) = 0 open("/tmp/pdk-deploy/fcb734befe617ec3ae1edc38da810a5a/libperl.so", O_RDONLY) = 3 read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300!\2\0004\0\0\0"..., 512) = 512 fstat64(3, {st_mode=S_IFREG|0664, st_size=1264090, ...}) = 0 mmap2(NULL, 1140104, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xfffffffff7d4e000 mmap2(0xf7e5a000, 45056, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10b) = 0xfffffffff7e5a000 close(3) = 0 rt_sigaction(SIGFPE, {0x1000000000000001, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|SA_SIGINFO|0x3d61cb8, (nil)}, {SIG_DFL, ~[HUP INT ILL ABRT BUS SEGV USR2 PIPE ALRM TERM STOP TSTP TTIN TTOU XCPU WINCH IO PWR SYS RTMIN RT_1 RT_2 RT_4 RT_5 RT_8 RT_9 RT_11 RT_12 RT_13 RT_16 RT_17 RT_18 RT_22 RT_24 RT_25 RT_26 RT_27 RT_28 RT_29 RT_30 RT_31], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 getuid32() = 501 geteuid32() = 501 getgid32() = 502 getegid32() = 502 open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = 3 fstat64(3, {st_mode=S_IFREG|0644, st_size=56454896, ...}) = 0 mmap2(NULL, 2097152, PROT_READ, MAP_PRIVATE, 3, 0) = 0xfffffffff7b4e000 mmap2(NULL, 241664, PROT_READ, MAP_PRIVATE, 3, 0x13ec) = 0xfffffffff7b13000 mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0x1466) = 0xfffffffff7b12000 close(3) = 0 mmap2(NULL, 135168, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xfffffffff7af1000 time(NULL) = 1348210009 readlink("/proc/self/exe", "/bin/ps"..., 4095) = 7 ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0 _llseek(0, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd618a8) = -1 EINVAL (Invalid argument) _llseek(1, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) ioctl(2, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd618a8) = -1 EINVAL (Invalid argument) _llseek(2, 0, 0xffd618d0, SEEK_CUR) = -1 ESPIPE (Illegal seek) open("/dev/null", O_RDONLY|O_LARGEFILE) = 3 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61978) = -1 ENOTTY (Inappropriate ioctl for device) _llseek(3, 0, [0], SEEK_CUR) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 brk(0x92dc000) = 0x92dc000 getppid() = 20212 stat64("/opt/ActivePerl-5.8/site/lib/sitecustomize.pl", 0xffd61560) = -1 ENOENT (No such file or directory) close(3) = 0 open("/usr/lib/.khostd/.hostconf", O_RDONLY|O_LARGEFILE) = 3 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61828) = -1 ENOTTY (Inappropriate ioctl for device) _llseek(3, 0, [0], SEEK_CUR) = 0 fstat64(3, {st_mode=S_IFREG|0644, st_size=334, ...}) = 0 fcntl64(3, F_SETFD, FD_CLOEXEC) = 0 read(3, "bindport=9001\ntrustip=221.122.57"..., 4096) = 334 read(3, "", 4096) = 0 close(3) = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20215 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) fstat64(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 read(3, (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) "tcp 0 0 0.0.0.0:9001"..., 4096) = 109 read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- fstat64(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0 close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [TRAP BUS FPE USR1 CHLD CONT TTOU VTALRM IO RTMIN], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_RESTART|SA_RESETHAND|0x22302d0}, 8) = 0 waitpid(20215, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20215 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [TRAP BUS FPE USR1 CHLD CONT TTOU VTALRM IO RTMIN], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 chdir("/usr/lib/.khostd") = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20218 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|0x3d61850, (nil)}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 waitpid(20218, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20218 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 chdir("/home/deploy") = 0 stat64("/etc/cron.hourly/hichina", {st_mode=S_IFREG|0755, st_size=711660, ...}) = 0 pipe([3, 4]) = 0 pipe([5, 6]) = 0 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0) = 20230 close(6) = 0 close(4) = 0 read(5, "", 4) = 0 close(5) = 0 ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xffd61868) = -1 EINVAL (Invalid argument) _llseek(3, 0, 0xffd61890, SEEK_CUR) = -1 ESPIPE (Illegal seek) read(3, "procps version 3.2.7\n", 4096) = 21 read(3, "", 4096) = 0 --- SIGCHLD (Child exited) @ 0 (0) --- close(3) = 0 rt_sigaction(SIGHUP, {0x1, [], SA_RESTORER|SA_STACK|SA_RESTART|SA_INTERRUPT|SA_NODEFER|SA_RESETHAND|0x3d61850, (nil)}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGINT, {0x1, [], SA_STACK|0x129b3d8}, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 rt_sigaction(SIGQUIT, {0x1, [], 0}, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, 8) = 0 waitpid(20230, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0) = 20230 rt_sigaction(SIGHUP, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGINT, {SIG_DFL, [HUP INT], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 rt_sigaction(SIGQUIT, {SIG_DFL, ~[HUP INT ILL TRAP KILL SEGV ALRM TERM STKFLT CHLD TSTP TTOU RT_1 RT_2 RT_3 RT_6 RT_9 RT_11 RT_14 RT_15 RT_16 RT_17 RT_20 RT_22], SA_NOCLDSTOP|SA_NOCLDWAIT}, NULL, 8) = 0 write(1, "procps version 3.2.7\n", 21procps version 3.2.7 ) = 21 munmap(0xf7af1000, 135168) = 0 munmap(0xf7e70000, 630784) = 0 munmap(0xf7f0a000, 634880) = 0 munmap(0xf7d4e000, 1140104) = 0 exit_group(0) = ? [ Process PID=20214 runs in 32 bit mode. ] Thank you very much.

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• How to call bash process from within django / wsgi?

  - by chang

  I'm using mod_wsgi apache2 adapter for a django site and I like to call some bash process within a view, using the usual ... p = subprocess.Popen("/home/example.com/restart-tomcat.sh", shell=True) sts = os.waitpid(p.pid, 0)[1] ... This code works perfectly from within a usual python shell but does nothing (I can trace right now) when called within django. Am I missing some wsgi constraints? The script has 755 perms, so it should be executable. Thanks.

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• Working with processes in C

  - by Gary

  Hi, just a quick question regarding C and processes. In my program, I create another child process and use a two-directional pipe to communicate between the child and parent. The child calls execl() to run yet another program. My question is: I want the parent to wait n amount of seconds and then check if the program that the child has run has exited (and with what status). Something like waitpid() but if the child doesn't exit in n seconds, I'd like to do something different.

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• About fork system call and global variables

  - by lurks

  I have this program in C++ that forks two new processes: #include <pthread.h> #include <iostream> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <cstdlib> using namespace std; int shared; void func(){ extern int shared; for (int i=0; i<10;i++) shared++; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } int main(){ extern int shared; pid_t p1,p2; int status; shared=0; if ((p1=fork())==0) {func();exit(0);}; if ((p2=fork())==0) {func();exit(0);}; for(int i=0;i<10;i++) shared++; waitpid(p1,&status,0); waitpid(p2,&status,0);; cout<<"shared variable is: "<<shared<<endl; cout<<"Process "<<getpid()<<", shared " <<shared<<", &shared " <<&shared<<endl; } The two forked processes make an increment on the shared variables and the parent process does the same. As the variable belongs to the data segment of each process, the final value is 10 because the increment is independent. However, the memory address of the shared variables is the same, you can try compiling and watching the output of the program. How can that be explained ? I cannot understand that, I thought I knew how the fork() works, but this seems very odd.. I need an explanation on why the address is the same, although they are separate variables.

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• printf anomaly after "fork()"

  - by pechenie

  OS: Linux, Language: pure C I'm moving forward in learning C progpramming in general, and C programming under UNIX in a special case :D So, I detected a strange (as for me) behaviour of the printf() function after using a fork() call. Let's take a look at simple test program: #include <stdio.h> #include <system.h> int main() { int pid; printf( "Hello, my pid is %d", getpid() ); pid = fork(); if( pid == 0 ) { printf( "\nI was forked! :D" ); sleep( 3 ); } else { waitpid( pid, NULL, 0 ); printf( "\n%d was forked!", pid ); } return 0; } In this case the output looks like: Hello, my pid is 1111 I was forked! :DHello, my pid is 1111 2222 was forked! Why the second "Hello" string occured in the child's output? Yes, it is exactly what the parent printed on it's start, with the parent's pid. But! If we place '\n' character in the end of each string we got the expected output: #include <stdio.h> #include <system.h> int main() { int pid; printf( "Hello, my pid is %d\n", getpid() ); // SIC!! pid = fork(); if( pid == 0 ) { printf( "I was forked! :D" ); //removed the '\n', no matter sleep( 3 ); } else { waitpid( pid, NULL, 0 ); printf( "\n%d was forked!", pid ); } return 0; } And the output looks like: Hello, my pid is 1111 I was forked! :D 2222 was forked! Why does it happen? Is it ... ummm ... correct behaviour? Or it's a kind of the 'bug'?

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• How do I implement the bg, &, and fg commands functionaliity in my custom unix shell program written in C

  - by user1631009

  I am extending the functionality of a custom unix shell which I wrote as part of my lab assignment. It currently supports all commands through execvp calls, in-built commands like pwd, cd, history, echo and export, and also redirection and pipes. Now I wanted to add support for running a command in background e.g. $ls -la& I also want to implement bg and fg job control commands. I know this can be achieved if I execute the command by forking a new child process and not waiting for it in the parent process. But how do I again bring this command to foreground using fg? I have the idea of entering each background command in a list assigning each of them a serial number. But I don't know how do I make the processes execute in the background, then bring them back to foreground. I guess wait() and waitpid() system calls would come handy but I am not that comfortable with them. I tried reading the man pages but still am in the dark. Can someone please explain in a layman's language how to achieve this in UNIX system programming? And does it have something to do with SIGCONT and SIGSTP signals?

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• How do I implement the bg, &, and bg commands functionaliity in my custom unix shell program written in C

  - by user1631009

  I am trying to extend the functionality of my custom unix shell which I earlier wrote as part of my lab assignment. It currently supports all commands through execvp calls, in-built commands like pwd, cd, history, echo and export, and also redirection and pipes. Now I wanted to add the support for running a command in background e.g. $ls -la& Now I also want to implement bg and fg job control commands. I know this can be achieved if I execute the command by forking a new child process and not waiting for it in the parent process. But how do I again bring this command to foreground using fg? I have the idea of entering each background command in a list assigning each of them a serial number. But I don't know how do I make the processes execute in the background, then bring them back to foreground. I guess wait() and waitpid() system calls would come handy but I am not that comfortable with them. I tried reading the man pages but still am in the dark. Can someone please explain in a layman's language how to achieve this in UNIX system programming? And does it have something to do with SIGCONT and SIGSTP signals?

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• C signals and processes

  - by Gary

  Hi, so basically I want "cmd_limit" to take a number in seconds which is the maximum time we'll wait for the child process (safe to assume there's only one) to finish. If the child process does finish during the sleep, I want cmd_limit to return pass and not run the rest of the cmd_limit code. Could anyone help me do this, here's what I've got so far.. int cmd_limit( int limit, int pid ) { signal( SIGCHLD, child_died ); sleep( limit ); kill( pid, SIGKILL ); printf("killin'\n"); return PASS; } void child_died( int sig ) { int stat_loc; /* child return information */ int status; /* child return status */ waitpid( -1, &stat_loc, WNOHANG ); if( WIFEXITED(stat_loc) ) { // program exited normally status = WEXITSTATUS( stat_loc ); /* get child exit status */ } printf("child died: %s\n", signal); }

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• Lighttpd server is stopped

  - by tomaszs

  I have a Lighttpd server plus mod_fastcgi. And today I had Internal Server Error 500. I've checked my error log and it goes like this: 2010-04-22 22:59:14: (server.c.1464) server stopped by UID = 0 PID = 3332 2010-04-22 22:59:15: (mod_fastcgi.c.1768) connect failed: No such file or directory on unix:/tmp/php.socket-5 2010-04-22 22:59:15: (mod_fastcgi.c.2956) backend died; we'll disable it for 5 seconds and send the request to another backend instead: reconnects: 0 load: 1 2010-04-22 22:59:15: (mod_fastcgi.c.2709) child died somehow, waitpid failed: 10 2010-04-22 22:59:15: (server.c.1464) server stopped by UID = 0 PID = 3332 2010-04-22 22:59:15: (server.c.1464) server stopped by UID = 48 PID = 1385 2010-04-22 22:59:15: (server.c.1464) server stopped by UID = 48 PID = 1385 2010-04-22 22:59:15: (server.c.1464) server stopped by UID = 48 PID = 1385 2010-04-22 22:59:15: (server.c.1464) server stopped by UID = 48 PID = 1385 What to do to find out what can be cause of this?

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• Spawning and waiting for child processes in Python

  - by Brendan Long

  The relevant part of the code looks like this: pids = [] for size in SIZES: pids.append(os.spawnv(os.P_NOWAIT, RESIZECMD, [RESIZECMD, lotsOfOptions])) # Wait for all spawned imagemagick processes to finish while pids: (pid, status) = os.waitpid(0, 0) if pid: pids.remove(pid) What this should be doing is spawning all of the processes off, then waiting for each process to finish before continuing. What it does is work for the most part but sometimes crash on the next section (when it expects all of these processes to be finished). Is there something wrong with this? Is there a better way of doing it? The environment it has to work on is CentOS with Python 2.4, but I'm testing on Cygwin with Python 2.5, so it could be that it fails on my machine but will work on the Linux one (the Linux machine is very slow and this error is rare, so I haven't been able to get it on there).

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• Shell job control

  - by user1535672

  For my school project I am implementing a shell and I need help with job control. If we type a command, say cat &, then because of the & it should run in background, but it's not working. I have this code: { int pid; int status; pid = fork(); if (pid == 0) { fprintf(stderr, "Child Job pid = %d\n", getpid()); execvp(arg1, arg2); } pid=getpid(); fprintf(stderr, "Child Job pid is = %d\n", getpid()); waitpid(pid, &status, 0); }

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• Nginx with PAM authentication through pam_script

  - by Envek

  Have anyone set up such a configuration? It's not work for me. So, I've installed nginx-extras on Ubuntu 12.04 (it's built with PAM module), and write to site config: location ^~ /restricted_place/ { auth_pam "Please specify login and password from main_site"; auth_pam_service_name "nginx"; } Afterwards, in /etc/pam.d/nginx: auth required pam_script.so dir=/path/to/my/auth_scripts And wrote simplest /path/to/my/auth_scripts/pam_script_auth (also I've tried to write complicated scripts) #!/bin/sh exit 0 # should allow anyone Doesn't work. The script is launched (I've wrote full functional script, that successfully executes, check credentials, writes to its own log and returns correct exit code, and executes noticeably long). But no access granted. Only rejected. In /var/log/nginx/error.log appears next record: 2012/09/13 10:44:42 [alert] 1666#0: waitpid() failed (10: No child processes) If I'm specify in /etc/pam.d/nginx: auth required pam_unix.so and grant for www-data user right to read /etc/shadow, unix authorization works fine. But script auth doesn't work. Can't understand, where is trouble. In nginx module, or in pam_script module.

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• How to deal with job that stop and cannot continue unless made foreground?

  - by Vi

  Recent example: mountlo (using UML): vi@vi-notebook:~/b$ mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other& [1] 32561 vi@vi-notebook:~/b$ Checking that ptrace can change system call numbers...OK Checking syscall emulation patch for ptrace...OK Checking advanced syscall emulation patch for ptrace...OK Checking PROT_EXEC mmap in /tmp...OK Checking for the skas3 patch in the host: - /proc/mm...not found - PTRACE_FAULTINFO...not found - PTRACE_LDT...not found UML running in SKAS0 mode [1]+ Stopped mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other vi@vi-notebook:~/b$ bg [1]+ mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other & [1]+ Stopped mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other vi@vi-notebook:~/b$ bg [1]+ mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other & [1]+ Stopped mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other vi@vi-notebook:~/b$ bg [1]+ mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other & [1]+ Stopped mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other vi@vi-notebook:~/b$ fg mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8,allow_other Linux version 2.6.15 (miko@dorka) (gcc version 3.3.5 (Debian 1:3.3.5-13)) #1 Mon Feb 27 13:27:52 CET 2006 (normal output) ... vi@vi-notebook:~/b$ socat - exec:'mountlo -m 16 -d /dev/uba1 /home/vi/mnt/usb -t vfat -o iocharset=utf8\,allow_other',pty,ctty fusermount: waitpid: No child processes vi@vi-notebook:~/b$ Also happens with Gimp (when it does run it's plug-ins). Parts of Gimp started by `gimp q.jpg&' freeze and cannot continue unless "killall -CONT" or made foreground. Is it a bug? How to reliably start things in a background?

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