Windows:

date /t
time/t
hostname
whoami (or echo %username%)
ipconfig
dir
type proof.txt
type network-secret.txt
systeminfo
net users
net localgroup administrators
ipconfig -all
route print
arp -a
netstat -ano
tasklist /svc
net start
net share
net use

Linux:

date
whoami
id
hostname
/sbin/ifconfig
pwd
ls -l
cat proof.txt
cat network-secret.txt
cat /etc/issue
uname -a
cat /etc/passwd
cat /etc/group
cat /etc/shadow
cat /etc/sudoers
ls -alh /var/mail/
ls -ahlR /root/
ls -ahlR /home/
who
w
last
/sbin/ifconfig -a
cat /etc/network/interfaces (or cat /etc/sysconfig/network)
arp -e
/sbin/route -nee
ps aux
ps -ef
cat /etc/services