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Old 09-18-2018, 07:14 AM   #1
ubin10
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inotifywatch usage


Hi..
I need to check a file if it is modified and will append that file into another file if so. 'inotifywatch' , should do the script, however when I tested the command :
Code:
inotifywait  -e modify  ~/test.txt --format '%w' |cat >test2.txt
then i modified test.txt from other console, seems inotify did the job, quit without any message (no error nor event report), and when i checked test2.txt, file was empty.
what i did wrong, help ?
edited : I'm using debian stretch on i386/32 bit

Thanks and regards

Last edited by ubin10; 09-18-2018 at 07:21 AM. Reason: adding information
 
Old 09-18-2018, 07:27 AM   #2
syg00
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Use xargs to execute the cat.
 
Old 09-18-2018, 10:29 AM   #3
ubin10
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Quote:
Originally Posted by syg00 View Post
Use xargs to execute the cat.
Thanks, I tested it :
Code:
inotifywait  -e modify  ~/test1.txt --format '%w''%f' | xargs cat >>test.txt
still no output on test.txt
interestingly, if I tried with 'access' event instead of modify, then it behave as what I expect (test1.txt is appended to test.txt)
Code:
inotifywait  -e modify  ~/test1.txt --format '%w''%f' | xargs cat >>test.txt
The problem is I only want to change test.txt when test1 is written/modified.
Is 'modify' event not implemented on inotifywait debian ?
 
Old 09-18-2018, 12:12 PM   #4
michaelk
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It depends on how test1.txt is written/modified. Here are all the events when you run the following command.

echo "hello" >> test1.txt

Quote:
/tmp/test.txt OPEN
/tmp/test.txt MODIFY
/tmp/test.txt CLOSE_WRITE,CLOSE
But if you modify test1.txt using a text editor the modify event is not triggered but instead you get these.
Quote:
/tmp/test1.txt OPEN
/tmp/test1.txt ACCESS
/tmp/test1.txt CLOSE_NOWRITE,CLOSE
/tmp/test1.txt OPEN
/tmp/test1.txt CLOSE_WRITE,CLOSE
/tmp/test1.txt ATTRIB
The events above were from the command
Quote:
inotifywait -m /tmp/test1.txt

Last edited by michaelk; 09-18-2018 at 12:15 PM.
 
Old 09-18-2018, 01:13 PM   #5
ubin10
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Quote:
Originally Posted by michaelk View Post
It depends on how test1.txt is written/modified. Here are all the events when you run the following command.
Ouch, well noticed. It definitely work using echo and cat,thanks
I plan to use php/web interface to modify the file, not sure if it will trigger event ?

Thank
 
Old 09-18-2018, 02:25 PM   #6
michaelk
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If you are using a web php script to modify the file, what is the purpose of using inotifywait?

Yes, you should get a modify event if use standard PHP file commands to open,write,close.
 
Old 09-18-2018, 02:58 PM   #7
ubin10
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Hi michaelk..php to write a single configuration file to make it user friendly, and inotify will further parsing it to triger script to restart services if the file is modified

regards
 
Old 09-25-2018, 02:29 PM   #8
dugan
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How about using entr instead of inotifywatch?

Code:
echo ~/test.txt | entr -s 'cat ~/test.txt >> test2.txt'

Last edited by dugan; 09-25-2018 at 02:37 PM.
 
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Old 09-25-2018, 06:00 PM   #9
syg00
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dugan, you find (and expose) some wonderful nuggets ...
 
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Old 09-25-2018, 08:01 PM   #10
ubin10
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Quote:
Originally Posted by dugan View Post
How about using entr instead of inotifywatch?

Code:
echo ~/test.txt | entr -s 'cat ~/test.txt >> test2.txt'
Perfect ! Thank you very much
 
  


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