My first reaction after logging into unknown *nix machines.
uptime
uname -a
w
who
df -h
free -m
cat /proc/cpuinfo
mount
top
ps aux
then check appropriate logs or dmesg etc
uptime
uname -a
w
who
df -h
free -m
cat /proc/cpuinfo
mount
top
ps aux
then check appropriate logs or dmesg etc