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Message #89104
[Bug 454722] Re: inotify does not watch /proc
#24 > Using inotifywait on /proc works fine too.
False, it does not notify you of new entries (like new processes
launched). Try the program below for proof; launch it and run "sleep
999" and you will not see the PID of your new sleep appear printed out.
Using inotify with /proc/ will probably never work, because the /proc/
entries are not files. They don't get updated until you look at them.
It's not a bug, it's a design "feature". See
http://unix.stackexchange.com/questions/74713/how-frequently-is-the-
proc-file-system-updated-on-linux?rq=1
If you want to monitor new procs under Linux, use a socket with NETLINK_CONNECTOR instead.
#include <stdlib.h>
#include <stdio.h>
#include <sys/inotify.h>
int main(int argc, char* argv[]){
int inotify_fd = inotify_init();
if (inotify_fd == -1) {
perror("inotify_init(): ");
}
// int watch_descriptor = inotify_add_watch(inotify_fd, "/proc", IN_CREATE);
int watch_descriptor = inotify_add_watch(inotify_fd, "/proc", IN_ALL_EVENTS);
if (watch_descriptor == -1) {
perror("inotify_add_watch(): ");
}
struct inotify_event *event;
char buf[1024];
ssize_t result;
// Watch forever, until signal (CTRL-C, etc.)
while(1)
{
result = read(inotify_fd, buf, sizeof(buf));
if (result == -1){
perror("read(): ");
}
// Print all events read from inotify_fd:
int index = 0;
while (index < result) {
event = (void *)(&buf[index]);
printf("index %d: %s\n", (int)index, event->name);
index += sizeof(struct inotify_event) + event->len;
}
printf("\n");
}
}
--
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https://bugs.launchpad.net/bugs/454722
Title:
inotify does not watch /proc
Status in “linux” package in Ubuntu:
Won't Fix
Bug description:
Compile the following program (inotifyerr.c)
#include <stdlib.h>
#include <stdio.h>
#include <sys/inotify.h>
int main(int argc, char* argv[]){
int fd = inotify_init();
if (fd == -1){
perror("inotify_init");
}
char path[256];
sprintf(path,"/proc/%s",argv[1]);
printf("watching %s\n",path);
int wd = inotify_add_watch(fd,path,IN_ALL_EVENTS);
if (wd == -1){
perror("inotify_add_watch");
}
char buf[1024];
ssize_t siz = read(fd,buf,1024);
if (siz == -1){
perror("inotify read");
}
printf("read done, bytes: %d\n",siz);
}
gcc inotifyerr.c
The program is supposed to watch events occurring on file /proc/nnn, where nnn is passed as
argument to program invokation.
Then start a process in background, and watch it with the program above. E.g.
$ sleep 20 &
[1] 8246
$ ls /proc/8246
attr cpuset io mountinfo pagemap smaps wchan
auxv cwd latency mounts personality stat
cgroup environ limits mountstats root statm
clear_refs exe loginuid net sched status
cmdline fd maps oom_adj schedstat syscall
coredump_filter fdinfo mem oom_score sessionid task
$ ./a.out 8246
watching /proc/8246
^C
[1]+ Done sleep 20
Note that the background process and the inotifyerr one are run from
within the same terminal, same user, and that the latter has read
access to the file being watched.
No events are reported.
The expected behaviour of inotify is to report events on /proc files
and directories instead.
Additional information:
I have run the same test also with superuser privileges, but the result
is the same.
I have modified the test program so as to make the process to whatch
a child of the inotifyerr one. In this case inotify catches all the events.
Ubuntu 9.04. 2.6.28-15-generic #52-Ubuntu SMP Wed Sep 9 10:49:34 UTC 2009 i686 GNU/Linux
---
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: i386
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: angelo 1376 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
Card hw:0 'NVidia'/'HDA NVidia at 0xfe028000 irq 23'
Mixer name : 'Realtek ALC888'
Components : 'HDA:10ec0888,1631e601,00100001'
Controls : 37
Simple ctrls : 21
DistroRelease: Ubuntu 10.04
HibernationDevice: RESUME=UUID=335bd2d5-504f-4410-a53a-96814ee336e8
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release i386 (20100429)
Lsusb:
Bus 002 Device 002: ID 046d:c315 Logitech, Inc. Classic New Touch Keyboard
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Packard Bell BV IMEDIA 8425
NonfreeKernelModules: nvidia
Package: linux (not installed)
ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-24-generic root=UUID=2258e664-9423-4566-ae33-52c12a4645ec ro quiet splash
ProcEnviron:
LANG=en_US.utf8
SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-24.41-generic 2.6.32.15+drm33.5
Regression: No
RelatedPackageVersions: linux-firmware 1.34.1
Reproducible: Yes
RfKill:
0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
Tags: lucid filesystem needs-upstream-testing
Uname: Linux 2.6.32-24-generic i686
UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
dmi.bios.date: 11/01/2006
dmi.bios.vendor: Phoenix Technologies, LTD
dmi.bios.version: M2N-NM 0401
dmi.board.name: M2N-NM
dmi.board.vendor: Packard Bell BV
dmi.board.version: 1.XX
dmi.chassis.asset.tag: 123456789000
dmi.chassis.type: 3
dmi.chassis.vendor: Packard Bell BV
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnPhoenixTechnologies,LTD:bvrM2N-NM0401:bd11/01/2006:svnPackardBellBV:pnIMEDIA8425:pvrPB80107506:rvnPackardBellBV:rnM2N-NM:rvr1.XX:cvnPackardBellBV:ct3:cvrChassisVersion:
dmi.product.name: IMEDIA 8425
dmi.product.version: PB80107506
dmi.sys.vendor: Packard Bell BV
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