Linux commands to check performance

1. vmstat
2. ps -aux
3. netcat
4. df
5. netstat
6. mstat, traceroute, ping
7. telnet to port to test remote server have port open
8. multiple binaries in /proc/ like /prod/cpuinfo
9. journctl -f
10. /var/log/syslog
11. tail, head, less, grep , sed and awk to filter logs

https://superuser.com/questions/117913/ps-aux-output-meaning