Shell Programming and Scripting

so lets say I have a process in cron that writes to a particular directory /var/tmp/EXAMPLEA

so, from time to time, say every couple of months, an upgrade is made. and here's how the upgrade works:

Code:

1. move the existing directory /var/tmp/EXAMPLEA somewhere else and name it differently...i.e. /var/tmp/EXAMPLEA-BKUP

2. create a new directory in its place, with the same name /var/tmp/EXAMPLEA

3. then, copy files that were in /var/tmp/EXAMPLEA-BKUP to /var/tmp/EXAMPLEA

Now, the problem is. after this upgrade is done, the process in cron does not resuming writing to the /var/tmp/EXAMPLEA directory even though everything is set up as it was before, with the write permissions and all.

can someone point in the direction of what the problem could be?

OS: Linux RedHat/CentOS/Ubuntu

Code?
My mind-reading glass-buble is currently out of order.

Well there's a question!!!! I'm just thinking aloud and writing here, I don't know that I'm correct...............

I guess it depends on whether the cron job has the files open when the update runs. If so, it will (internally) be writing to specific inode numbers rather than specific files. In stage 3 when you 'copy' the files back to the original directory you create new inodes for those files. I'd be inclined to try renaming the files using 'mv' in stage 3 rather than 'cp'.

Let's see what other members suggest but that's my immediate thoughts.

That means you have currently running something.

Not without knowing where,what and how it is done.

One could make sure none of those files are open at the time the script is working with them.
Like, creating a lock file or something.

Otherwise... Need code!

Are the files in /var/tmp/EXAMPLEA-BKUP growing after they were moved there from /var/tmp/EXAMPLEA?

If processes that were writing to those files had them open when they were moved and continue writing to the file descriptors that were used when they were opened, creating a new directory (with the old name or another name) will not cause those processes to magically start writing to a different file than they were writing to before. (And, note once a file descriptor is open, the file associated with that file descriptor is defined by the file system it is on and its i-node number; not by the pathname it had when it was opened.)

i presumed it had to be related to inodes.

and no, the files in /var/tmp/EXAMPLEA-BKUP do not continue growing when they're renamed. I think what I can try doing next time is:

1. Make sure the cron job is commented out or any application writing to the directories are shut down
2. And, as suggested by hicksd8, i can also use mv, instead of cp

Note that the following sequence of operations:

Code:

mv /var/tmp/EXAMPLEA /var/tmp/EXAMPLEA-BKUP
mkdir /var/tmp/EXAMPLEA
mv /var/tmp/EXAMPLEA-BKUP/* /var/tmp/EXAMPLEA

leaves you with an empty /var/tmp/EXAMPLEA-BKUP directory, and creates a period of time where files being written into /var/tmp/EXAMPLEA will be destroyed by replacing them with files being copied or moved from /var/tmp/EXAMPLEA-BKUP to /var/tmp/EXAMPLEA.

If you want to make a backup of files currently in a directory to a backup directory, it usually makes a lot more sense to do something more like:

Code:

rm -rf /var/tmp/EXAMPLEA-BKUP
mkdir /var/tmp/EXAMPLEA-BKUP
cp /var/tmp/EXAMPLEA/* /var/tmp/EXAMPLEA-BKUP

which never leaves /var/tmp/EXAMPLEA non-existent and never destroys any files that exist in that directory at the time the backup is created.