Q. I need to run a program called oraMon.pl. However this program is run from cron job. It report error to stderr and normal output to stdout. How do I save stdout, stderr and both into 3 separate log files?
A. It is not that hard if you know howto redirect stderr, stdout and a small command called tee.
=> fd0 is stdin
=> fd1 is stdout
=> fd2 is stderr
There are two formats for redirecting standard output and standard error:
For example anything written to fd2 to the same place as output to fd1, you will use:
tee command read from standard input and write to standard output and file.
So to send stderr to /tmp/errors.log, stdout to /tmp/output.log and both to /tmp/final.log, type as follows:
((/path/to/oraMon.pl 2>&1 1>&3 | tee /tmp/errors.log) 3>&1 1>&2 | tee /tmp/output.log) > /tmp/final.log 2>&1
Read bash man page and tee command for more information.