run inotifywait on background - bash

Question

I have this code copied from linuxaria.com as example and work just fine on my case the problem is when I exit from terminal inotifywait stop. I want run on back ground even after exit the terminal. how I can do that?
#!/bin/sh
# CONFIGURATION
DIR="/tmp"
EVENTS="create"
FIFO="/tmp/inotify2.fifo"
on_event() {
local date=$1
local time=$2
local file=$3
sleep 5
echo "$date $time Fichier créé: $file"
}
# MAIN
if [ ! -e "$FIFO" ]
then
mkfifo "$FIFO"
fi
inotifywait -m -e "$EVENTS" --timefmt '%Y-%m-%d %H:%M:%S' --format '%T %f' "$DIR" > "$FIFO" &
INOTIFY_PID=$!
while read date time file
do
on_event $date $time $file &
done < "$FIFO"

Answer 1

You can run the script with screen or nohup but I'm not sure how that would help since the script does not appear to log its output to any file.
nohup bash script.sh </dev/null >/dev/null 2>&1 &
Or
screen -dm bash script.sh </dev/null >/dev/null 2>&1 &
Disown could also apply:
bash script.sh </dev/null >/dev/null 2>&1 & disown
You should just test which one would not allow the command to suspend or hang up when the terminal exits.
If you want to log the output to a file, you can try these versions:
nohup bash script.sh </dev/null >/path/to/logfile 2>&1 &
screen -dm bash script.sh </dev/null >/path/to/logfile 2>&1 &
bash script.sh </dev/null >/path/to/logfile 2>&1 & disown

Answer 2

I made a 'service' out of it. So I could stop/start it like a normal service and also it would start after a reboot:
This was made on a Centos distro So I'm not if it works on others right away.
Create a file with execute right on in the service directory
/etc/init.d/servicename
#!/bin/bash
# chkconfig: 2345 90 60
case "$1" in
start)
nohup SCRIPT.SH > /dev/null 2>&1 &
echo $!>/var/run/SCRIPT.SH.pid
;;
stop)
pkill -P `cat /var/run/SCRIPT.SH.pid`
rm /var/run/SCRIPT.SH.pid
;;
restart)
$0 stop
$0 start
;;
status)
if [ -e /var/run/SCRIPT.SH.pid ]; then
echo SCRIPT.SH is running, pid=`cat /var/run/SCRIPT.SH.pid`
else
echo SCRIPT.SH is not running
exit 1
fi
;;
*)
echo "Usage: $0 {start|stop|status|restart}"
esac
exit 0
Everything in caps you should change to what your script name.
The line # chkconfig: 2345 90 60 makes it possible to start the service when the system is rebooted. this probably doens't work in ubuntu like distro's.

Answer 3

The best way I found is to create a systemd service.
Create systemd file in /lib/systemd/system/checkfile.service:
sudo vim /lib/systemd/system/checkfile.service
And paste this there:
[Unit]
Description = Run inotifywait in backgoround
[Service]
User=ubuntu
Group=ubuntu
ExecStart=/bin/bash /path_to/script.sh
RestartSec=10
[Install]
WantedBy=multi-user.target
and in /path_to/script.sh, you can have this:
inotifywait -m /path-to-dir -e create -e moved_to |
while read dir action file; do
echo "The file '$file' appeared in directory '$dir' via '$action'" >> /dir/event.txt
done
Make sure that your file is executable by the user:
sudo chmod +x /path_to/script.sh
After creating two files, reload systemd manager configuration with:
sudo systemctl daemon-reload
Now you can use start/stop/enable to your script:
sudo systemctl enable checkfile
sudo systemctl start checkfile
Make sure to replace file/directory/user/group values before executing.

Answer 4

replace -m with
-d -o /dev/null
ie:
inotifywait -d -o /dev/null -e "$EVENTS" --timefmt '%Y-%m-%d %H:%M:%S' --format '%T %f' >"$DIR" > "$FIFO" & INOTIFY_PID=$!
You can check the inotifywait help manual at:
https://helpmanual.io/help/inotifywait/

Answer 5

Method that will work even if the file to be watched is not there yet, or gets deleted in between (just watch the whole directory instead of a single file, and then do the action on a particular file):
nohup inotifywait -m -e close_write /var/opt/some_directory/ |
while read -r directory events filename; do
if [ "$filename" = "file_to_be_watched.log" ]; then
# do your stuff here; I'm just printing the events to file
echo "$events" >> /tmp/events.log
fi
done &