cron job to detect new files

rblampain · 12-24-2005, 09:35 AM

I need to have a cron job detecting the insertion of new files in a directory and its subdirectories and trigger a PHP script if there is a new file or new files.

The idea is to do some maintenance if there are new file(s) and chmod these files from 644 to 444. The cron job would run every ten seconds or so.

My knowledge of PHP and BASH is very basic and I have no idea how to do this, could anyone make a suggestion? I hope it's simple enough.

Thank you for your help.

acid_kewpie · 12-26-2005, 11:31 AM

cron doesn't run more often than once a minute, and that's really not what cron is for. it'd also have to be a pretty crude solution that would need to run from a cron script. There are tools like fam (might have been renamed gam recently... not sure) which will watch a filesystem intelligently and notify you of changes as you tell it to. you should have a look at things like this to help you out.

dugas · 12-26-2005, 06:45 PM

You could have the cron call a script that has a loop that uses the sleep command.

rblampain · 12-26-2005, 09:30 PM

Thank you for your answers. I saw a little bit of info about FAM, it seems to have some problems concerning recursive directories and subdirectories and the "sleep" mode (in cron job) keeps the processor busy.

Would you have any comment?

paulsm4 · 12-26-2005, 11:35 PM

I tend to agree with acid_kewpie both that "cron" is probably not a good choice, and that you probably want to investigate other tools that are out there, for example, "inotify":

http://www-128.ibm.com/developerwork...l-inotify.html

For the sake of argument, however, could you get by with a simple script that does something like this (pseudo-code only):

Code:

  N=60
  while true; do
    for dir in `cat SOME_DIRS.LST`; do
      ls -lt | awk '{ SOME PROCESSING ON THE TIMESTAMP-SORTED OUTPUT FOR THIS DIRECTORY }' > CURRENT FILES.LST
      if (diff CURRENT_FILES.LST PREVIOUS_FILES.LST); then
         PROCESS NEW FILES
      fi
    done
    mv CURRENT_FILES.LIST PREVIOUS_FILES.LST
    sleep N
  done

bigearsbilly · 12-28-2005, 05:26 AM

Quote:

Originally Posted by dugas

You could have the cron call a script that has a loop that uses the sleep command.

Ugggh! That's awful.
Off to bed with no tea.

hamster · 12-28-2005, 05:44 AM

I get that sort of request sometimes in Projects myself. Thanks

bigearsbilly · 12-28-2005, 06:03 AM

why not
touch a timestamp file each time and use find -newer

Code:

find . -newer stamp
touch stamp

or even better, touch -t to give an explicit timestamp.

Code:

touch -t DDMMYYYHHMM stamp
find . -newer stamp

rblampain · 12-28-2005, 08:51 AM

Thank you all, I've got plenty to try now.