Write Naemon Log

We can write to naemon.log file by issue command

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 )

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

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

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 ​here
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 file​ with in this page

[krit@mini log-viewer-1.0.1]$ ./logviewer.sh 

Convert epoch time to human on Log file

ref ​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