tail -f或更少+ F如何突出显示新行

Question

Is there any way to highlight, ie bold, or colorize new added lines since last change?

For example, I am watching a log file with multiple similar errors in PHP error_log (different line or function name, etc)... And I have to look at timestamps where one set of errors ends and another begins (page refresh)

It would be very helpful if there is a way to highlight, but only last added lines.

I am looking for solution to run on macOS and Linux in console.

Answer 1

Check out the watch command, if your system has it. The command:

watch -d tail /your/file/here

will display the file and highlight the differences character by character. Note that you do not want to use the -f option in this case.

Ubuntu has it. For OSX, you can can use brew install watch if you have homebrew installed or sudo ports install watch if you use ports .

Another bonus is that it works for any command that has output that changes over time. We have even used it with ls -l to watch the progress of backups and file compressions.

Answer 2

"tail" itself does not offer a serious way to do this. But give "multitail" a closer look:

https://www.vanheusden.com/multitail/

And for Mac OSX:

http://macappstore.org/multitail/

Answer 3

Turn on grep 's line buffering mode.

1. Using tail

    tail -f fileName | grep --line-buffered my_pattern 

2. Using less

    less +F fileName | grep --line-buffered my_pattern 

3. Using watch & tail to highlight new lines

    watch -d tail fileName 

Note: For linux based systems.