Network
Check listening ports:
netstat -plnt
Sniff the network on a port or ip-address:
tcpdump port <portnr> tcpdump src/dst <ip-addr>
Check the network performance:
iftop (-n) (network perfomance) iftop -bNP -i eth0 ifstat
System activity
Check all processes from a user and press c for the full path names:
top -u <username>
Memory:
vmstat cat /proc/meminfo
Hard disks:
iostat
Processors:
lscpu cat /proc/cpuinfo
User activity
Logged on users:
w
Last logged on users:
last
I/O Performance
Check what drive you want to monitor:
lsblk
Once the drive is know you can start the monitoring, for this you can use iotop or iostat:
iostat -dxm 5 <device> iostat -dxm 5 | grep <device>
These commands will provide extensive information for a specific device. The refresh will be done every 5 seconds, you can increase or decrease this number.
Processes
Check the running processes:
ps -ef
This command will show a list of information about every process currently running.
VI
| Command | Result |
|---|---|
| i | Insert text |
| r | Replace character |
| x | Remove character |
| dd | Remove line |
| yy | Copy line |
| p | Paste line |
| V | Virtual select text |
| G | Go to end of file |
| H | Go to start of file |
| ZZ | Save file and exit |
| dw | Remove a word |
| c<number>w | Remove the following x words |
| :q! | Do not save file and exit |
| :g/^#/d | Remove all lines starting with a # |
| :s/<search>/<replace>/g | Find/replace |
| :sort | Sort the selected content |
| :%sort | Sort all the lines alphabetically |