I am creating an application that writes to a log file, and I need to know how in Linux / Bash to continuously display the log file to the screen (updating the screen with every new line put into the log).
So as an example, lets say I want to push a running log of apache/error.log to the screen (ssh terminal) continuously updating.
Try the tail command:
tail -f filename
--follow=name you'll be sure to keep the content of the log file displayed even if the file has been rotated/recreated by a cron job.
Another solution is
less +F filename
or just less filename and typing "F" into it (pressing shift+f). It can be better than tail, because it allows you to cancel continuous printing temporary, go backward to look something and reenable it with "F" (shift+f) again
-S flag, while allowing you to scroll left/right through them. Superior to the tail -f file.log | cut ... method.
F then Shift? Or press them simultaneously? I tried but it made no difference.
The watch command can also be of use.
watch tail logfile
Would show you the last 5 lines of the log file. It can be extended to any command which prints stuff to stdout.
Yes, using tail -f is the traditional solution, but depending on what you are trying to do, this might work better.
You can also:
less filename.txt
and press 'F'
has one plus - you can anytime CTRL-C and scroll back in log and start watching again with the 'F'.
ssh {remotehost} tail -n0f {logfile}
This will give you zero lines initially, and continuously print any new lines that appear in the file.
