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I'm running Ubuntu 14.04 and I want to monitor a folder and drop a mail if new files are not added every 30 mins.
I referred below as well.
How I can monitor new files in a directory and move/rename them into another directory?
I'm not sure how to wait for a period and check for new files in a folder.
You might be able to do something as simple as:
#!/bin/bash
targetDir="$1"
while true; do
files=("$targetDir"/*)
sleep 30m ## wait 30 minutes
files1=("$targetDir/"*)
if [[ ${#files[@]} == ${#files1[@]} ]]; then
echo "No new files added" | mail user@example.com
fi
done
Save that script as ~/bin/watch.sh or whatever you like, make it executable (chmod a+x ~/bin/watch.sh) and run it giving it the target directory as an argument:
watch.sh /path/to/dir
Now, that is a very naive approach and simply counts the number of files every 30 minutes. So if one file is deleted but another one added, it will think there are no new files. It would probably be a better idea to take the timestamp of the newest file and check if it was last modified more than 30 minutes ago:
#!/bin/bash
targetDir="$1"
newest=0;
while true; do
## Wait for half an hour. This is done at the beginning of the loop
## to ensure we wait a half hour before the first check
sleep 30m
## Get the current time in seconds since the epoch
now=$(date '+%s')
for file in "$targetDir"/*; do
## Get the file's modification time in seconds since the epoch
lastMod=$(stat -c "%Y" "$file")
## Is this file newer than the current newest?
if [[ $lastMod -gt $newest ]]; then
newest=$lastMod
fi
done
## If the newest file is older than half an hour
if [[ $((now - newest)) -gt 1800 ]]; then
echo "No new files added since $(date -d '- 30 min')" |
mail user@example.com
fi
done
If you don't want to run a script for ever like that, you could instead write one that checks the timestamps and call the script every 30 minutes:
#!/bin/bash
targetDir="$1"
newest=0;
for file in "$targetDir"/*; do
## Get the file's modification time in seconds since the epoch
lastMod=$(stat -c "%Y" "$file")
## Is this file newer than the current newest?
if [[ $lastMod -gt $newest ]]; then
newest=$lastMod
fi
done
## Get the current time in seconds since the epoch
now=$(date '+%s')
## If the newest file is older than half an hour
if [[ $((now - newest)) -gt 1800 ]]; then
echo "No new files added since $(date -d '- 30 min')" |
mail user@example.com
fi
Now, save that as ~/bin/watch.sh and make it executable (chmod a+x ~/bin/watch.sh). Then, run crontab -e and add this line:
*/30 * * * * /home/techie/bin/watch.sh
Save the file (saving adds the crontab) and you're done. The script will be run every 30 minutes.
Before checking for new files, I would use "stat" on the directory itself and see if the timestamp changes.
$ stat $PWD
File: ‘/home/paulm/SCRATCH’
Size: 6144 Blocks: 8 IO Block: 32768 directory
Device: 26h/38d Inode: 10937103831396301849 Links: 6
Access: (0775/drwxrwxr-x) Uid: ( 520/ paulm) Gid: ( 1020/ paulm)
Access: 2019-07-09 13:17:15.528000000 +0000
Modify: 2019-07-09 13:17:15.528000000 +0000
Change: 2019-07-09 13:17:15.528000000 +0000
Birth: -
$ touch bar
$ stat $PWD
File: ‘/home/paulm/SCRATCH’
Size: 6144 Blocks: 8 IO Block: 32768 directory
Device: 26h/38d Inode: 10937103831396301849 Links: 6
Access: (0775/drwxrwxr-x) Uid: ( 520/ paulm) Gid: ( 1020/ paulm)
Access: 2019-07-09 13:23:11.346000000 +0000
Modify: 2019-07-09 13:23:11.346000000 +0000
Change: 2019-07-09 13:23:11.346000000 +0000
Birth: -
if the date on the directory changes, then it's worth looking for new files, this should be a lot more efficient.
touch foo an hour later and the directory's mtime is still the same. But adding/removing files is reflected there.
The answers so far assume that files only go into a directory and never go out. But what if you have a script that empties the directory periodically? Then the script could miss the fact a file went into the directory 5 minutes ago but was processed and taken out.
Another option is using the inotifywait command written in highly efficient C language for the express purposes of monitoring file and directory creation and modification. You can install it with the command:
sudo apt install inotify-tools
The psuedo-code for an appropriate script would be:
You would call the script from a place like /etc/rc.local so it runs when machine is booted.
The advantage of this methodology is you aren't checking the directory every 30 minutes but rather you are checking it 30 minutes after the last changes to the directory.
There is a nifty utility for precisely this task:
cronto run a script every 30min and then the script itself that will check the directory and send email can be written in pretty any language likebash,pythonorphp...