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Cory J
Asked: 2010-04-15 13:27:42 +0800 CST

"watching" a log on FreeBSD vs Linux

  • 772

On Linux systems I can

watch -n1 tail /var/log/whatever.log

or

watch -n1 grep somestuff /var/log/whatever.log

To show updates to a log every 1 seconds. On FreeBSD however, the watch command does something else entirely. Who knows a good FreeBSD command for what I'm trying to do? =)

linux logging freebsd grep tail

6 Answers

  1. Best Answer

    How about this: $ tail -f logfile?

    And if you need to grep: $ tail -f logfile | grep foobar.

    • 20 
  2. Port:   gnu-watch-3.2.8
Path:   /usr/ports/misc/gnu-watch
Info:   GNU watch command
Maint:  ehaupt[ woof-woof ]FreeBSD.org
B-deps: 
R-deps: 
WWW:    http://procps.sourceforge.net/
    • 8
    • Linux: watch -n 5 tail /var/logfile
    • Freebsd: cmdwatch -n 5 /var/logfile
    • Openbsd: gnuwatch -n 5 /var/logfile

    (Install from Ports for the BSDs)

    • 4

  4. You could write a quick shell loop:

    while sleep 1; do clear; grep somestuff /var/log/whatever.log | head -n 18; done

    • 2

  5. If I define your "what I'm trying to do" as "watch changes to a log file", I would suggest rather than using watch that you could just use the "-f" (for "follow") or "-F" option on the tail command, as in tail -f /var/log/whatever.log. The output can also be piped through grep to give you the filtered version you show there. I believe this is also likely to be more efficient than "watch".

    Edit: I thought the "follow" option wasn't available on BSD but it appears it is. Must have been thinking of something else that's not there...

    • 2

  6. You can use this script for all things that you want to do with watch command.

    #!/usr/local/bin/bash
while [ true ]
do
clear
date
echo ------------------------------------
eval "$@"
sleep 2
done

    Usage:sh scriptname.sh example:sh scriptname.sh ls -l

    • 0