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How to write a daemon in Unix?

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# 1  
Old 10-24-2006
How to write a daemon in Unix?


I have a directory where sometimes a file will come (in a name format say file001.txt).
I want to run a job (.ksh file) as soon as a new file comes into the directory.

How can I write a shell script which will run in the background and monitor arrival of new file in the directory?

Thanks in advance.
# 2  
Old 10-24-2006
Look in to cron jobs, you can write a script to monitor files, depending on what you to do. Put this script in a cronjob, the cron will wake up run the script. The cron wakes up once every minute, and looks for jobs to run.


# 3  
Old 10-24-2006
Here's a brute force method using ksh:
while true; do
  if [[ -s file001.txt ]]; then
    # Found the file; do stuff here
    print "found file!"
    break # stop the loop

The loop cycles forever, checking whether the file exists, and stops checking once found. You may want to consider the relative effect (if any) of having a script running constantly like this. A cron job that runs every minute might be a better choice, depending on your requirements.
# 4  
Old 10-25-2006
i would suggest the above script with a sleep interval in between for every check.
# 5  
Old 04-18-2008

HI Glenn i tired this code it gives me an error "Can't find file" & still echoes the output desired, i would also like to add sleep intervals within the loop can you explain or send the code to achieve that
# 6  
Old 04-18-2008
time intervals for the script

Hi all,Matrix,Glenn
can you help me in setting a script which checks for a file within every 10 mins,...script should have time intervals in between
below code checks the file but gives an error msg cant find file & then again prints the output found file

while true; do
if [[ -e file001.txt ]]; then
# Found the file; do stuff here
print "found file!"
break # stop the loop

Last edited by Yogesh Sawant; 04-21-2008 at 06:35 AM.. Reason: added code tags
# 7  
Old 04-18-2008
this should have been a new thread Smilie

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