Questions[logging](ubuntu)

What does this UFW log mean? Has already asked a similar question, but I want to know explicitly what each line of the UFW log means

Feb  6 16:27:08 jonasgroenbek kernel: [71910.873115] 
[UFW BLOCK] IN=eth0 OUT= 
MAC=a6:8d:e2:51:62:4c:f0:4b:3a:4f:80:30:08:00 
SRC=77.72.85.26 DST=157.230.26.180
LEN=40 TOS=0x00 PREC=0x00 TTL=251 ID=62215 PROTO=TCP 
SPT=42772 DPT=3194 WINDOW=1024                        
RES=0x00 SYN URGP=0

For my (and hopefully others) feasibility, I would very much like each individual part being described shortly.

When working remotely I set a server to force an fsck at boot time with the sudo touch /forcefsck command and rebooted.

After it restarted I checked in /var/log/fsck for the results of the disk check.
Both checkfs and checkroot said: Nothing has been logged yet

So where is it saving the results?

I just got a message from the default disk analyses software (Baobab) that I only have 1GB left on the hard drive. After some search, I found that the /var/log/ folder is the cause of this.

Some file/sizes in /var/log/:

• kern.log = 12.6 GB
• ufw.log = 12.5 GB
• kern.log.1 = 6.1 GB
• ufw.log.1 = 6.0 GB

Et cetera et cetera. /var/log is huge.

Can I delete those files or the entire /var/log folder? Or is that a BIG NO NO in Ubuntu?

For the purposes of kernel logging, why do I have three different, non-inclusive levels of logging amongst /var/log/messages, /var/log/syslog, and /var/log/kern.log?

I have used top to see the memory usage at the moment. But I would like to monitor the memory usage over a period of time. E.g start monitoring and then execute a few commands, and final stop the monitoring and see how much memory that have been used during the period.

How can I do this on Ubuntu Server?

I guess I could start a cronjob every 5th second or so, and invoke a command that log the current memory usage in a textfile. But what command should I use to get the current memory usage in a format that is easy to log to a text file?