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CRON Scripts

Posted on 1998-07-13
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I am new to the Unix OS and I have to write a CRON scritps which will search an Oracle DB alert.log for "ORA-" errors every 20 minutes. When these errors are found, I would like an e-mail sent you to a distribution list.The machine is running IRIX unix and a default C shell. What I am looking for is a script(well explained what each line does) which I could modify and learn from. If you have a script like this place post and/or sent to john.hagen@shaw.ca
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Question by:hagenj
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16 Comments
 
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Author Comment

by:hagenj
ID: 2008742
Edited text of question
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by:blowfish
ID: 2008743
In order to extract lines containing a certain string (in this case "ORA-") from a file, use the grep (Global Regular Expression Parser) command as follows, substitute the full path to your log file where I have put "/opt/oracle/alert.log" ;

  grep "ORA-" /opt/oracle/alert.log

In order to mail the extracted output to yourself, or a distribution list, pipe the output of the grep command into mailx, like so;

  grep "ORA-" /opt/oracle/alert.log | mailx -s "Oracle Errors" distribution@company.com

The -s switch gives you a Subject line.  

You could write a script to do this, but it is only two commands.  You could just put the whole command line into the crontab entry, which would look like this, assuming that it is scheduled to run at 5, 25, and 45 minutes after each hour;

05,25,45 * * * * grep "ORA-" /opt/oracle/alert.log | mailx -s "Oracle Errors" distribution@company.com

The first 5 colums in the crontab entry are;
  minutes (range 00-59),
  hour (range 00-23),
  day of month (range 1-28 or 29 or 30 or 31 depending on month and year)
  month of year (range 1-12)
  day of week (sun=0, mon=01 .. sat=06)


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by:hajek
ID: 2008744
blowfish:
a) I'd use full path to command (/bin/grep)
b) I'd rather create script and call the script (single command) from cron (cron line
05,25,45 * * * * /where/command/is/command
and grep & other stuff was in the script "command")

the essential one:
c)I believe hagenj meant "send me errors which occured since last
control (during last 20 minutes)". In case you have a few well known, long-time-ago errors in log, you will mail them again and again.
This makes the question a little more difficult ..

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by:hagenj
ID: 2008745
Hajek, is right I am looking for only new errors which have taken place in the last 20 minutes, and I am looking for a script. Sorry for not saying that.
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by:hagenj
ID: 2008746
Adjusted points to 250
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by:Staplehead
ID: 2008747
john,

would you please post an example line from your alert.log?  you can xxx out any of the text; i'd be important, though, to see the position of the ORA-#### tags and the date/time stamp.

larry
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by:hagenj
ID: 2008748
Tue Jul 14 00:38:04 1998
Thread 1 advanced to log sequence 28188
  Current log# 3 seq# 28188 mem# 0: /*****/*****/*****/log03a.dbf
  Current log# 3 seq# 28188 mem# 1: /*****/*****/*****/log03b.dbf
Tue Jul 14 00:41:17 1998
Thread 1 advanced to log sequence 28189
  Current log# 1 seq# 28189 mem# 0: /*****/*****/*****/log01a.dbf
  Current log# 1 seq# 28189 mem# 1: /*****/*****/*****/log01b.dbf
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by:hagenj
ID: 2008749
Sat May  2 23:46:21 1998
Errors in file /*****/*****/*****/*****/*****/*****/ora_20254.trc:
ORA-07445: exception encountered: core dump [11] [] [] [] [] []
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by:hagenj
ID: 2008750
Above Blowfish wrote
grep "ORA-" /opt/oracle/alert.log | mailx -s "Oracle Errors" distribution@company.com
How whould I enter two or more e-mail address instead of the distribution list

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Expert Comment

by:braveheart
ID: 2008751
Don't forget that cron jobs do not execute shell initialisation files (.profile, .cshrc,...) unless you explicitly source them in the script which you fire off. This is why it is a good idea to give a full path name for commands.
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by:hajek
ID: 2008752
the solution very strongly depends on whether Oracle keeps the log file open (Informix does not.) Try command
  fuser -u _log_file_
(when database is working) a few times.
If it does not return user, who have the file open, at least
once time, you can believe the file is not opened all time.
Now you can do in you control script for example this:
-----------------------------------------
mv log_file /tmp/log_file.new   ## logs from last control
>log_file   ## creates empty log file
grep _ERROR_ /tmp/log_file.new > /tmp/log_file.err ## errors to special file
NRERR=`wc -l /tmp/log_file.err|cut -f1 -d" "`  ## # of errors into variable NRERR
if [ "NRERR" != "0" ] ; then  ## when it is >0, send mail
  cat /tmp/log_file.err|mailx -s "JESUS ! WHAT IS WRONG ??"
fi
cat /tmp/log_file.new >> log_file.controlled ## appends all just controlled new log to file log_file.controlled
-------------------------------------------------
PS: script for ksh (korn shell), you may need to alter for sh

This works ONLY when ORACLE only appends to log_file and does not it keep opened all time.


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by:blowfish
ID: 2008753
hajek's method will work: you need to extract all messages issued since the last time your script ran.  Once you have that info, you grep for errors, and if the count of lines extracted is > 0, send out the results via e-mail.  

To answer your previous question regarding mailx and multiple recipients, just list them at the end of the mailx command like so:

  grep "xyz" file.name | mailx -s "subject" user1@domain.com user2@domain.com user3@domain.com user4@domain.com

Alternativly, since you are writing a shell script you may want to use a variable like this;

  RECIPIENT="user1@domain.com user2@domain.com user3@domain.com user4@domain.com"

  grep "xyz" file.name | mailx -s "subject" ${RECIPIENT}

You may prefer to create a distribution list in sendmail.  To do this locate your sendmail aliases file, usually /etc/aliases (or /etc/mail/aliases) and add the following line to it;

  ora-errors: user1@domain.com, user2@domain.com, user3@domain.com, user4@domain.com

after you save the file, run newaliases to compile the sendmail aliases database.  

To test your alias, run the following sendmail command;

  /usr/lib/sendmail -bv ora-errors

That command will expand the alias from the sendmail alias database and print out each recipient's email address.  

If you create the distribution list in sendmail then change the mailx command like so:

  grep "xyz" file.name | mailx -s "subject" ora-errors


--cheers
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Expert Comment

by:hajek
ID: 2008754
ehmm, a little correction to my script:
..
if [ "$NRERR" != "0" ] ; then
..
I forgot the "$"...


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by:hagenj
ID: 2008755
For Hajek, it looks like yours answer is going to look, so just answer the question and I will accept it, sorry Blowfish but i can only give pints to one.
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Expert Comment

by:blowfish
ID: 2008756
That's all part of the "game", he beat me to it.  
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Accepted Solution

by:
hajek earned 750 total points
ID: 2008757
The solution very strongly depends on whether Oracle keeps the log file open (Informix does not.) Try command
       fuser -u _log_file_
(when database is working) a few times. If it does not return user, who have the file open, at least once time, you can believe the file is not opened all time.
Now you can do in you control script for example this:
-----------------------------------------
mv log_file /tmp/log_file.new   ## logs from last control
>log_file   ## creates empty log file
## grep returns 0 when it found pattern, 1 when pattern is not found
NRERR=`grep _ERROR_ /tmp/log_file.new > /tmp/log_file.err; echo $?` ## errors to special file
if [ "$NRERR" = "0" ] ; then  ## when something found, send mail
    cat /tmp/log_file.err|mailx -s "JESUS ! WHAT IS WRONG ??" _the_unhappy_man
fi
cat /tmp/log_file.new >> log_file.controlled ## appends all just controlled new log to file log_file.controlled
-------------------------------------------------
PS: script for ksh (korn shell), you may need to alter for sh
PS2: there is little change in the script - now a result of grep is taken as error indicator

This works ONLY when ORACLE only appends to log_file and does not it keep opened all time.
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