Command Description
mpstat 1 Displays processors related statistics
vmstat 2 Displays virtual memory statistics
iostat 2 Displays I/O statistics
tail -n 500 /var/log/messages Displays the last 500 kernel/syslog messages
tcpdump -i eth1 Captures all packets flow on interface eth1. With -w switch you can specify a file where you can direct the output to
lsof Lists all open files belonging to all active processes
free -m Shows RAM memory details
watch df -h Watches changeable disk usage continuously
tcpdump -i eth0 ‘port 80’ Monitors all traffic on port 80 on interface eth0
lsof -u testuser Lists files opened by a specific user