Shell Programming and Scripting

I need help to do a script that will compress a file that's bigger than 5000 octets and won't overwrite the previous compress file.

lets say I have mylogfile.log and I would compress it I would become
mylogfile. 1. log and if I would compress again mylogfile.log it would be
mylogfile. 2. log.

My script(doesn't work)

Code:

if  [-f myfilelog.log < 5000 ] ; then
  for i in $(/var/log/mrfilelog.log)
do
 zip myfilelog.i.log
fi

Thanks for your answer.

I don't think repeated compression is a good idea. It can lead to file corruption.

I suggest to tar the file first and then apply a bzip2 compression on top of that.

Code:

tar myfilelog.log.tar myfilelog.log
bzip2 myfilelog.log.tar

---------- Post updated at 14:41 ---------- Previous update was at 14:32 ----------

BTW if you want to create a new file name each time you compress, then here is syntax:-

Code:

for i in {1..3}
do
  zip myfilelog.${i}.log myfilelog.log 
done

I hope this helps.

what does tar do?

Usually, zip needs a zip archive file to save to. For compressed content, zip just copies, so there is no waste. Generally, compressing twice makes a third file bigger than the second.

You can make a compressed copy of an open file in a new file ( "compress <old >new" or "gzip <old >new" and zip as far as it works with open files ) but it lacks data integrity as the original is still growing. You can break really big files apart, especially logs with time stamps, where it is pretty easy to break them into days, months or years.

Usually, you rotate the log file first, so it is not attached, and then you archive it. Many servers will restart (reopen) the log, so you rename it (so the name is open -- legal while attached, as they are logging on an open fd to an inode unless they are shell scripts, and sometimes even (...)>then) and send then a signal with kill to the logging daemon. Many use 'logrotate' and 'cron' for this.

tar is an archiving utility. You can check the manual pages here for further reference.

tar is an archiver somewhat like zip, older and not tied to the archive file so closely, not doing updates, deletions and such that zip does.

Thanks guy your helping me a lot i'm new at this, so ya thanks