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Old 08-10-2015, 04:29 PM   #1
Registered: Sep 2005
Location: Bangladesh
Distribution: RH 7.2, 8, 9, Fedora
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bash script

A bit confused... can't figure out how... can somebody be my angel guide???

I am taking images from a cam as an snapshot. it's sending me files. Now, I need a bash script that will rename the latest file (file names are hard to guess based on sequence numbers... I can only give partial name like* where the names are IP+date+time+many other things...) to mycam1image.jpeg

and then delete existing old files... like rm -rf*

Thus only the latest file will be replaced and previous files will be removed. Now, i must detect the latest file, as if for some case there are multiple, then i have to use the latest under any cost.

and it needs to be run in a cronjob (the script) on a per minute (or 5 mins ) basis.

Any ideas???

Old 08-10-2015, 05:02 PM   #2
Keith Hedger
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Registered: Jun 2010
Location: Wiltshire, UK
Distribution: Linux From Scratch, Slackware64, Partedmagic
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you can use the find command to find by date you can also use the stat command to get file info like size and date have a look at the man pages for those commands, also show what you have tried and also a listing of the folder containing the image filesnso we have a better idea of the format of the file names, the more info you give the easier it is for us to help
Old 08-11-2015, 03:37 AM   #3
Registered: Apr 2013
Location: Massachusetts
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There are many ways to do it. If you only receive pictures from the IP address, you could use the following script and invoke it from cron:

cd /directory/where/the/files/may/exist

if [ $(ls*.jpeg 2>/dev/null | wc -l) -ge 2 ] # do not delete files unless two or more exist
    rm $(ls -rt*.jpeg | head --lines=-1) # list in order of modtime, select all but the most recent, delete

if [ $(ls*.jpeg 2>/dev/null | wc -l) -ge 1 ] # do not mv file unless one (or more) exists
    mv $(ls -rt*.jpeg | tail --lines=1) mycam1image.jpeg # mv most recent file to target filename
If there are no new webcam images, the script will do nothing.
If there are two or more new images, the script will delete all but the most recent.
The newest webcam image will be renamed, overwriting the target file if necessary.
If new webcam images appears after the rm and before the mv, the script will mv the most recent.

Edit: There is one problem. If there are no new files, the script generates error messages ("ls: cannot access*.jpeg: No such file or directory"), though it correctly does nothing else. The error messages can be discarded with 2>/dev/null as I have added above. There may be a more elegant method which does not generate or require special handling of these error message.

Last edited by Beryllos; 08-11-2015 at 04:20 AM. Reason: possible error message
1 members found this post helpful.
Old 08-11-2015, 05:33 AM   #4
Registered: Sep 2005
Location: Bangladesh
Distribution: RH 7.2, 8, 9, Fedora
Posts: 217

Original Poster
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that works so far... thanks a lot for the assistance...

it removes all the files... and keeps the renamed one... my camera takes 5 pics in 1 sec interval on every 5 mins. and then the cron job executes it on 6th min (cron runs per minute). one min lag from the cam time stamp... but who cares??

Thanks again Truly



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