Shell Programming and Scripting

Bash on RHEL 6.2

We have multiple shell scripts executed by cron jobs. Each Shell script has its own log files currently. Most of them have logs generated using spool command from Oracle RDBMS's sqlplus commmand.

Sample:

Code:

    #!/bin/bash

    sqlplus -s scott/tiger << EOF

    spool /home/oracle/scripts/logs/script1.log

    Some SQL goes here;

    spool off

    quit
    EOF

Now, our log monitoring team wants to have just one log file where all the shell scripts will scripts write to. We'll call it the 'CentralLogFile.log' for this discussion.

They say it is easy for their log mining tools to search for keywords in one log file rather than multiple log files. They will rotate this CentrallogFile file on a monthly basis.

But, I do not want to stop the current way of shell scripts generating separate log files for each execution. I want the shell scripts to write to both the CentralLogFile and the dedicated log file.

I found a simple & Elegant solution by Corona in the following link

Enable logging from within the shell script

Code:

exec >logfile
exec 2>&1

So, is it OK if use the following commands in red lines in all of my scripts so that it will write to the central log as well ?
Do you see any drawbacks, issues with this approach ?

Code:

#!/bin/bash

exec >/home/oracle/logmaster/CentralLogFile.log 
exec 2>&1

sqlplus -s scott/tiger << EOF

spool /home/oracle/scripts/logs/script1.log

Some SQL goes here;

spool off

quit
EOF

It will work, but it will overwrite the logfile every time. You might want to do exec >> logfile instead, so it appends.

Do you expect these scripts to produce output all the time, or are they supposed to be completely silent except for errors?

Thank You very much Corona.

Yes. All output must be captured to the central log. So, the following should work. Right ?

Code:

exec >> /home/oracle/logmaster/centrallog.txt
exec 2>&1

BTW...I don't need to use two greater than symbols for the second line as show below

Code:

exec 2>>&1

. Right ?

Nope. Since you're not opening a file, just copying a stream, nothing's truncated.

I don't think it will work.
1) the exec redirection will redirect stdout and stderr to some file, but the sql spool directive will open a new file without considering the redirection. It might work if you drop the spool.
2) With your exec you only open/redirect to one single file. There's nothing done to write dedicated AND central log files. The tee command provides a second etc. output stream, but I don't know how it could be used for this request.

Thank You corona.

Hi Rudic
I did a quick test with the following script. It writes to both script1.log and CentralLogFile.log . Need to test this in the actual scripts.

Code:

#!/bin/bash
exec >> /home/oracle/SCRIPTS/lgq/CentralLogFile.log
exec 2>&1
sqlplus -s "/ as sysdba" << EOF
spool /home/oracle/SCRIPTS/lgq/script1.log
alter session set nls_date_format='DD-MM-YYYY HH24:MI';
select sysdate from dual;
select sysdate+1 from dual;
select 'ajab' from dual;

spool off


quit
EOF