= Write Naemon Log =

We can write to naemon.log file by issue command 
{{{
#!sh
OMD[monitor@501264b41d2d]:~/var/naemon$ pwd
/omd/sites/monitor/var/naemon
OMD[monitor@501264b41d2d]:~/var/naemon$ echo "[$(date +%s)] User Activity msg TEST log" >> naemon.log 
}}}
Linux command '''date +%s''' will print time in current time since Epoch 1970

In C program, we can implement this function with bash shell via '''system( bash cmd )'''
{{{
#!C
int writeLogFile( char *msg )
{
   char str_msg[1024];
   sprintf( str_msg, "echo \"[%d] User Activity %s \" >> /omd/sites/monitor/var/naemon/naemon.log",(int)time(NULL), msg);
   printf(str_msg);
   system(str_msg);
   return 0;
}
}}}

== logrotate ==
we can config naemon.log to rotate as following
{{{
#!sh
OMD[monitor@906094f86a76]:~/etc/logrotate.d$ more /omd/sites/monitor/etc/logrotate.d/naemon 
/omd/sites/monitor/var/naemon/naemon.log {
    daily
    rotate 7
    nocompress
    olddir /omd/sites/monitor/var/naemon/archive
    dateext
    dateformat -%Y%m%d
    missingok
    notifempty
    postrotate
      [ -f /omd/sites/monitor/tmp/lock/naemon.lock ] && kill -s USR1 `cat /omd/sites/monitor/tmp/lock/naemon.lock`
    endscript
    create 0664 monitor monitor
}

/omd/sites/monitor/var/naemon/livestatus.log {
        missingok
        rotate 0
        compress
        delaycompress
        notifempty
        create 640 monitor monitor
}

}}}

A file thruk.log was an activity user log. We can logrotate as following
{{{
#!sh
OMD[monitor@906094f86a76]:~/etc/logrotate.d$ more /omd/sites/monitor/etc/logrotate.d/thruk  
/omd/sites/monitor/var/log/thruk.log {
        daily
        rotate 3
        nocompress
        olddir /omd/sites/monitor/var/log/archive
        dateext
        dateformat -%Y%m%d
        missingok
        notifempty
        create 660 monitor monitor
}

/omd/sites/monitor/var/thruk/cron.log {
        missingok
        rotate 0
        compress
        delaycompress
        notifempty
        create 660 monitor monitor
}

}}} 

== Log viewer ==
Ref [https://github.com/sevdokimov/log-viewer, here][[br]]
We use this java v8 to run as web server on port 8111 and browse the log file and show on web page.
File can be download from the web or in attach [attachment:log-viewer-1.0.1.zip file] with in this page
{{{
#!sh
[krit@mini log-viewer-1.0.1]$ ./logviewer.sh 
}}} 

== Convert epoch time to human on Log file ==

ref [https://unix.stackexchange.com/questions/623046/convert-replace-time-from-epoch-milliseconds-to-human-readable-date-in-logfiles here]

Example: file.log
{{{
1522693524403 entity1,sometext
1522693541466 entity2,sometext
1522693547273 entity1,sometext
}}}

Just use

{{{
$ awk '{$1 = strftime("%F %T", substr($1,1,10))} 1' file.log
2018-04-02 21:25:24 entity1,sometext
2018-04-02 21:25:41 entity2,sometext
2018-04-02 21:25:47 entity1,sometext
}}}

With milliseconds

{{{
$ awk '{$1 = strftime("%F %T", substr($1,1,10)) "." substr($1,11)} 1' file.log
2018-04-02 21:25:24.403 entity1,sometext
2018-04-02 21:25:41.466 entity2,sometext
2018-04-02 21:25:47.273 entity1,sometext
}}}