Shell Programming and Scripting

Hello all, this is my first post while i am trying to understand unix.
I would basically like to know if i can do this:
Lets say i have a folderA and folderB
And i save something in folderA

Can i make a script that checks folderA latest file, then compares it with the date of latest file in folder B
If the file in folderA is newer that the last file in folderB then copy it on FolderB rename it to something.
Repeat this infinitely

So even if i delete the contents of folderA i will have a backup of all files in folderB

I am not sure how to proceed or if that is possible.
Thanks in advance for any info!

i can suggest you to go through the man pages of commands like
test
find
using test command you can test for newer file and find will help you to locate the file in folders then you can use cp or mv according to your req.

thanks for your answer!
I am going to look into it and letu know more questions!

$ ls -tr folderA | tail -1
Will give you the newest file.

So you could use:

Code:

LATEST=`ls -tr folderA | tail -1`
cp "folderA/${LATEST}" "folderB/${LATEST}".$$

Put the above in a script and call it from cron (if running once per minute is enough?) and $$ will be a different PID each time the script runs.

Or use a script something like, if the newest file in FolderA is going to change names each time:

Code:

PREVLATEST=""
while [ 1 ]; do
LATEST=`ls -tr folderA | tail -1`
if [ "${LATEST}" != "${PREVLATEST}" ]; then
  cp "folderA/${LATEST}" "folderB/${LATEST}"
  PREVLATEST="${LATEST}"
done

Call the script thus: nohup ./scriptname & and it would just keep running (you might want to put a sleep in their somewhere!

HTH

Tony

Tony thanks so much i will give it a try!!!!!

hello there, i tried it and it doesnt work
I tried to code below:

Code:

PREVLATEST=""
while [ 1 ]; do
LATEST=`ls -tr /var/Folder1/ | tail -1`
if [ "${LATEST}" != "${PREVLATEST}" ]; then
  cp "/var/Folder1/${LATEST}" "/var/Folder2/${LATEST}"
  PREVLATEST="${LATEST}"
done

I save this on a file.sh then i run it at the startup as a daemon.

Seems like nothing is happening.
any directions?

Put a set -x at the top of the script and run it in a terminal window to see what it is doing, a sleep of some period just before the done might be advisable (say 3 seconds?)

If the set -x spits out too much on the screen then put:

Code:

echo PREVLATEST = ${PREVLATEST} LATEST = ${LATEST}

before the if line and put:

Code:

echo cp "/var/Folder1/${LATEST}" "/var/Folder2/${LATEST}"

before the actual copy line instead of using set -x.

To run it as a daemon from within a terminal window you can do:

Code:

# nohup ./script.sh &