I'm monitoring a log file (it's a PBX queue file, it's written to when a call comes in and it's the result of what happens to the call, whether the caller hangs up, etc)
Here's what I have:
while inotifywait -m -e close_write /var/log/asterisk/queue_log_test;
do
if [ tail -n1 /var/log/asterisk/queue_log | grep EXITWITHTIMEOUT ];
then
php /usr/local/scripts/queue_monitor/pbx_queue_timeout.php
elif [ tail -n1 /var/log/asterisk/queue_log | grep ABANDON ];
then
php /usr/local/scripts/queue_monitor/pbx_queue_abandon.php
elif [ tail -n1 /var/log/asterisk/queue_log | grep COMPLETE ];
then
php /usr/local/scripts/queue_monitor/pbx_queue_complete.php
else
# Don't do anything unless we've found one of those
:
fi
done
Now, if I run the script, it successfully sets up the watches and detects the change/close (I've tried both MODIFY and CLOSE_WRITE, both work)
Setting up watches.
Watches established.
/var/log/asterisk/queue_log_test CLOSE_WRITE,CLOSE
But the event is never triggered (I have tested the PHP scripts outside of the inotify script and they execute splendidly)
If I run a tail by hand of the file that's being watched, it's successful and finds the phrase:
[root#pbx ...local/scripts/queue_monitor]: tail /var/log/asterisk/queue_log_test
ABANDON
[Load: 0.00] [Time: 19:04:43]
[root#pbx ...local/scripts/queue_monitor]:
What is it I'm missing here?
You are using the -m switch of inotifywait, which makes it run indefinitely:
-m, --monitor
Instead of exiting after receiving a single event, execute
indefinitely. The default behaviour is to exit after the first
event occurs.
And the while loop is waiting for it to finish, so it can evaluate is exit code to decide if the loop should continue or not.
Related
It seems that when my screen is locked for some period of time, my S.gpg-agent.ssh disappears, and so in order to continue using my key I have to re-initialise it.
Obviously, this is a relatively frequent occurrence, so I've written a function for my shell to kill gpg-agent, restart it, and reset the appropriate environment variables.
This may be a bit of an 'X-Y problem', X being above this line, but I think Y below is more generally useful to know anyway.
How can I automatically run a command when an extant file no longer exists?
The best I've come up with is:
nohup echo "$file" | entr $command &
at login. But entr runs a command when files change, not just deletion, so it's not clear to me how that will behave with a socket.
According to your comment, cron daemon does not fit.
Watch socket file deletion
Try auditd
# auditctl -w /var/run/<your_socket_file> -p wa
$ tail -f /var/log/audit/audit.log | grep 'nametype=DELETE'
Howto run a script if event occurred
If you want to run a script on socketile deletion, you can use while loop, e.g.:
tail -Fn0 /var/log/audit/audit.log | grep 'name=<your_socket_file>' | grep 'nametype=DELETE' \
while IFS= read -r line; do
# your script here
done
thx to Tom Klino and his answer
You don't mention the OS you're using, but if it's linux, you can use inotifywait from the inotify-tools package:
#!/bin/sh
while inotifywait -qq -e delete_self /path/to/S.gpg-agent.ssh; do
echo "Socket was deleted!"
# Recreate it.
done
I'm working on a script which need to detect the first call to FFMPEG in a program and run a script from then on.
the core code was like:
strace -f -etrace=execve <program> 2>&1 | grep <some_pattern> | <run_some_script>
The desired behaviours is, when the first greped result comes out, the script should start. And if nothing matched before <program> terminates, the script should be ignored.
The main problem is how to conditionally execute the script based on the grep's output and how to terminate the script after the program terminates.
I think the first one could be solved using read, since the greped text are used as signals, its contents are irrelevant:
... | read -N 1 && <run_some_script>
and the second could be solved using broken pipe mechanism:
<run_some_script> > >(...)
but I don't know how to make them work together. Or is there a better solution?
You could ask grep to just match the pattern once and return and make it return a success error code. Putting this together in a if conditional altogether as
if strace -f -etrace=execve <program> 2>&1 | grep -q <some_pattern>; then
echo 'run a program'
fi
The -q flag is to suppress the usual stdout content returned by the grep command as you've mentioned you only want to use grep result to perform an action and not use the results.
Or may be you needed to use coproc running the command to run in background and check every line of the output produced. Just write a wrapper over the command you want to run as below. The function is not needed for single commands but for multiple commands a function would be more relevant.
wrapper() { strace -f -etrace=execve <program> 2>&1 ; }
Use coproc is just similar to running the command in background but provides an easy way to capture the output of the command run
coproc outputfd { wrapper; }
Now watch the output of the commands run inside wrapper by reading from the file descriptor provided by coproc. The below code will watch on the output and on the first match of the pattern it starts a background job for the command to run and the process id is stored in pid.
flag=1
while IFS= read -r -u "${outputfd[0]}" output; do
if [[ $output == *"pattern"* && $flag -eq 1 ]]; then
flag=0
command_to_run & pid=$!
fi
done
When the loop terminates, which means the background job started by coproc is complete. At that point kill the script started. For safety purposes, see if its alive and do the kill
kill "$pid" >/dev/null 2>&1
Using the ifne util:
strace -f -etrace=execve <program> 2>&1 |
grep <some_pattern> | ifne <some_script>
I want to write an if condition in Shell script something like this:
if[ tail -10f logFile | grep -q "RUNNING" ]
So the idea is I have restarted my server and want to perform some action only after the server is started up(RUNNING). So I want to continuously tail the log and check if the server is in RUNNING mode again.
The issue with the above approach is it does not exits even after the server is RUNNING and goes into infinite loop. No code in if or else is printed.
What about?
while [ $(tail -10 logFile | grep -c RUNNING) -eq 0 ]; do sleep 1; done
I wrote a script to run constantly on startup. If for whatever reason the script were to fail, I wrote a second script to check if it has failed, and if so, run the first script again. I then set this second script as a cronjob to run every minute so that it is constantly checking if the first script is alive.
So to test this, I reboot my system. I can see in htop that the first script is running from start up as expected. Good. I kill the process to test the second script. Sure enough, the second script starts the first script again. Still good. I then kill this process, but the second script won't run again now. It still updates a txt file when I manually start the first script, but the second script just doesn't start the first script like it's supposed to. Is it because I killed the cronjob? Restarting the cron service doesn't fix anything though, so I don't know why my second script isn't running again at all.
First script:
#!/bin/bash
stamp=$(date +%Y%m%d-%H%M)
timeout 10d tcpdump -i eth0 -s 96 -z gzip -C 10 -w /home/user/Documents/${stamp}
Second script:
#!/bin/bash
echo "not running" > /home/working.txt
if (( $(ps -ef | grep -v grep | grep tcpdump.sh | wc -l) > 0 ))
then
echo "tcpdump is running!!!" > /home/working.txt
else
/usr/local/bin/tcpdump.sh start
fi
Any help?
You would probably be better off running a simple for loop as the main script, and that kicks off the tcpdump script in the background, so something like:
#!/bin/bash
while true; do
if ps -ef | grep -v grep | grep -q tcpdump; then
: tcpdump running OK
else
# tcpdump not running - start it off
nohup /usr/local/bin/firstscript.sh start &
fi
sleep 30
done
This checks that "tcpdump.sh" is in the output of the "ps -ef" command - if it is, then do nothing (note that you must have an actual command between the "then" and "else" - the ":" command, which just takes it s arguments and ignores them, is sufficient). If it isn't running, start the first script in the background. Then sleep 30 seconds and check again. (Yes, I could have inverted the test so that I didn't need an empty "then" arm, but it would have made the code less obvious)
You put this script as the one which starts at boot time.
Edit: Do you really want to check for "tcpdump.sh"? Is that what the first script is actually called? Assuming that you actually want to check for the tcpdump program, you could use:
if pgrep tcpdump; then
I have a script:
nohup tail -f /somefile >> /soemeotherfile.dat &
nohup while inotifywait -e close_write /someotherfile.dat; do ./script.sh; done &
but it seems that script.sh is never activated despite input arriving at the tail of /somefile every 5 minutes. What is wrong with my script above?
From the inotifywait docs:
close_write
A watched file or a file within a watched directory was closed, after being opened in writeable mode. This does not necessarily imply the file was written to.
close_write only triggers when a file is closed.
tail -f /somefile >> /soemeotherfile.dat
...continually appends to someotherfile.dat. It does not close it after each individual write.
Probably you want the modify event instead.