View a Log File in Linux Dynamically

Viewing updates of a dynamically generated log on a remote linux server from a windows machine

You can try klogg. It is a fork of glogg. Glogg opens files in such a way that may prevent other programs from accessing them, that is described here. That has been fixed in klogg(see the issue for details).

How can I view log files in Linux and apply custom filters while viewing?

Try the multitail tool - as well as letting you view multile logs at once, I'm pretty sure it lets you apply regex filters interactively.

How to read a dynamically changing file

the way i think i would go about it is this:

first of all i will create a bash script and a text file, the bash script will first store the number of lines of that log file in the text file, then add a cron of that script.

the script will count the lines of that file and compare it to the number of lines stored in the text file

you can do that using the command

wc -l filename

if the number of lines is bigger then the log has been updated, i will calculate the current number of lines minus the number stored in the text field, and by that i will know how many lines have been added since last check, then use this command to fetch those lines

tail -n $number_of_lines filename

and i will loop through the output and do the desired action if one of the lines matches your criteria and then update the text file which holds the number of lines, i would have written you the bash script but i guess you got the idea

EDIT: you can execute this script (just write your code which searches for the matches etc)

#!/bin/bash

NUMBER=`/bin/cat ./numberoflines`
LINES=`/usr/bin/wc -l < /var/log/messages`

DIFFERENCE=$(($LINES-$NUMBER))

if [ $DIFFERENCE != 0 ]; then
tail -n $DIFFERENCE /var/log/messages |while read line
do
if $( echo $line | grep --quiet 'New USB device found' )
then
        # Email text/message
        EMAIL='youremail@gmail.com'
        SUBJECT="New USB device found"
        EMAILMESSAGE="/tmp/emailmessage.txt"
        echo "New USB device found etc ..." > $EMAILMESSAGE
        /bin/mail -s "$SUBJECT" "$EMAIL" < $EMAILMESSAGE
fi
done
echo "$LINES" > ./numberoflines
fi

EVEN if you cannot add anything to crons then you still can execute this script anyway, see what you want to match and check and execute the code you need there

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