CODEWITHSUNDEEP
linuxbashconsole
Leachim
Leachim

Reputation: 69

tail -f OR less +F how to highlight new lines

Is there any way to highlight, i.e. 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.

Upvotes: 1

Views: 2178

Answers (3)

pvrforpranavvr
pvrforpranavvr

Reputation: 2948

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.

Upvotes: 2

Greg Tarsa
Greg Tarsa

Reputation: 1642

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.

Upvotes: 1

BigSN
BigSN

Reputation: 1023

"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/

Upvotes: 0

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