Linux – Colour tail of Apache logs

Logrotate can be made to only keep one copy of a logfile... If you RTFM you'll find the following bit regarding configuration settings:

rotate count
    Log files are rotated count times before being removed or mailed to the 
    address specified in a mail directive. If count is  0,  old  versions  
    are  removed  rather than rotated.

You can couple rotate with size, again from the logrotate(8) man page, to keep the file size small. While not by number of lines but by k, M, G size.

size size
    Log  files  are rotated when they grow bigger than size bytes. If size is 
    followed by M, the size if assumed to be in megabytes.  If the G suffix is 
    used, the size  is  in gigabytes.   If  the k is used, the size is in 
    kilobytes. So size 100, size 100k, and size 100M are all valid.

Since there is only one job active at a time, completed job logs are moved to /joblogs/completed_jobs/job_* and the logs are short, this hokey workaround is OK for now:

while [ 1 == 1 ] ; do for joblog in `ls /joblogs/job_*/JOB.LOG`; do cat $joblog; done; sleep 10; done