UNIX for Dummies Questions & Answers

I have few solaris-10 non global zones, where one application is writing some logs to /var/ovd/ConfigLogs. It keeps increasing all the time, as it is needed by application team as of now. I want a small script, which I can configure in cronjob, which should :
- Run every Saturday 10 PM
- Copy /var/ovd/ConfigLogs to /var/ovd/ConfigLogs.1
- Nullyfy /var/ovd/ConfigLogs
- bzip /var/ovd/ConfigLogs.1
- Next Saturday (Second cronjob), it should repeat, but should ot overwrite /var/ovd/ConfigLogs.1.bz
I am still trying to understand if logadm can help me in this. Can somebody help me for this script to put in cronjob ?

I am no Solaris expert and do not know "logadm", but this should be fairly straightforward. Some things you have to keep in mind:

1. You should - under no circumstances - change the inode of the log, otherwise processes which have still opened this file (inode) would keep writing into it. You need to "zap" the file: replace its contents with a single "EOF"-marker, provided by "/dev/null". Do it this way:

Code:

cat /dev/null > /path/to/logfile

2. If you copy the file to another location this process needs time. In the meantime the process writing to the log might put something into it and you would lose that when you "zap" the file. You will have to decide how big this risk is (based on the frequency with which the logfile gets written - if there is one message per minute the risk of dropping a log message is practically negligeable, if it is 10 messages per second it is considerable). Note, though, that the risk never drops to zero, so if you need complete logs no matter what you will have to elaborate on the process.

3. How to configure a cron entry is in the manual, if you have problems with this i suggest you search for it here, there are examples galore. One thing you have to keep in mind when writing the cron job is the "Cron Error Number One".

I hope this helps.

bakunin

I can write a simple script and set it up in cronjob, as below

Code:

/usr/bin/cp -p /var/ovd/ConfigLogs /var/ovd/ConfigLogs.1
cat /dev/null > /var/ovd/ConfigLogs
/usr/bin/bzip2 /var/ovd/ConfigLogs.1

But next time Saturday, it will overwrite /var/ovd/ConfigLogs.1. how should I prevent it ? I am not good in programming. It should create another files with extension of .1, .2, .3 and so on.

You can do

Code:

LOG=/var/ovd/ConfigLogs
m=5
for n in 4 3 2 1
do
  [ -f $LOG.$n.bz2 ] && mv $LOG.$n.bz2 $LOG.$m.bz2
  m=$n
done
cp -p $LOG $LOG.1
> $LOG
bzip2 $LOG.1

---------- Post updated at 07:08 PM ---------- Previous update was at 06:29 PM ----------

A crontab entry logs like this

Code:

00 10 * * 5 /path/to/rotatescript

and can be created with e.g.

Code:

EDITOR=vi crontab -e

--
If you have root rights I would go for logadm. It is only one command

Code:

logadm -w /var/ovd/ConfigLogs -c -C 5 -p 1w -z 0 -P 'Sat Nov 02 10:00:00 2013'

and an entry is added to /etc/logadm.conf.
No crontab entry is needed, because the existing logadm entry handles all the /etc/logadm.conf.

Thanks. I tested it with current time and it worked. But logadm seems to be more effective. You command is good, but a small modification is needed here. Now apps team wants that all logs should be copied/compressed inside newly created directory - /var/ovd/Config-Backup-Logs instead of /var/ovd.
How should I get it configured in /etc/logadm.conf ?

It is possible, but they are paying you - not me...
In the script you can change the variable LOG to only the base filename, and prefix the directories in the mv and test command, and maybe even modify the bzip2 command. But actually this is very unusual - all logrotate-like commands default to keep the backups in the same directory.
Regarding the logadm, the -t template option might be suitable.
More details about logadm and bzip2 are in the man pages:

Code:

man logadm
man bzip2