Shell Programming and Scripting

I am using Solaris 9. I wish to run my script every 1 minute inteval. Though i can run it using below entry in crontab.

* * * * /export/home/username/script/file_exist_&_run.sh

in short above script will check whether a specific file exist in a directory. If it found it will inovke another script to execute.

In fact, when a user will put a specific file in a directory only then it will execute. However, this will occur less


one of the experts advise better use daemon-like script or 'at' command which will be in loop....something like that Rather using shortinterval script in Crontab?

Experts could you please help me to get the dameon-like script for 1 minute interval..??
//purple

Code:

while :
do
 # do something here
 sleep 60
done

Hi Danmero,

Well i will put my script in #do something here.. Then I will run your script manually and will it be running contineously??

while :
do
# do something here
sleep 60
done

Another thing... do you think is there any possiblity of facing problem if i run the script in crontab by 1 minute interval? why short interval is not recommended in crontab?

Why do you think short internal is not recommended in crontab? Any reason for that?

If such short interval is not recommended then an approximate granularity would be already provided by cron implementation itself and as far as I know there is no specification that short interval is not recommended.

With an ever running daemon dedicated for each and every such process, will consume more resources and its not an optimized approach unlike the usage of cron entries.

Using cron is clean, easy to modify, maintain and only one daemon cron-d runs all the time and the actual processes that are kicked off are just cron-d instance spawned and exec'd as the process mentioned in the cron-entry

Yes

Yes, if you start a process and the process don't finish in one minute the cron will start a second process and another one until ...

And this should be controlled by implementing same-instance check in the process itself or best by a generic wrapper

or to implement logic based on lock file such that at any point of time in a host only one instance of process 'p1' runs

Well, I tried put the script in Crontab for 1 minute interval- as i said the script check whether a specific file exist in a directory. If it found it will inovke another script to execute.
* * * * /export/home/username/script/file_exist_&_run.sh

In fact, whenever a user will put a specific file in a directory only then it will execute. However, user will put the file rare.

so every 1 minute a mail is generated and goes to user(/var/mail/...) mail box. How to stop that mail. otherwise it consumes lotof space and important mail will be missed.

in mail produced the following output:

*.txt: No such file or directory

So, crontab is not good for my purpose....any suggestion.