Append text to stderr redirects in bash

Question

Right now I\'m using exec to redirect stderr to an error log with

exec 2>> ${errorLog}

The only downside is that I have to start each

Answer 1

cat q23123  2> tmp_file ;cat tmp_file | sed -e "s/^/$(date '+[%F %T]'): /g" >> output.log; rm -f tmp_file