[sweeks@sweeks-laptop ~]$ exec 3>/tmp/lolcats
[sweeks@sweeks-laptop ~]$ exec 4>/tmp/walrus
[sweeks@sweeks-laptop ~]$ ls -l /proc/self/fd/{3,4}
l-wx------. 1 sweeks sweeks 64 Dec  7 16:51 /proc/self/fd/3 -> /tmp/lolcats
l-wx------. 1 sweeks sweeks 64 Dec  7 16:51 /proc/self/fd/4 -> /tmp/walrus
[sweeks@sweeks-laptop ~]$ exec 4>&3
[sweeks@sweeks-laptop ~]$ ls -l /proc/self/fd/{3,4}
l-wx------. 1 sweeks sweeks 64 Dec  7 16:51 /proc/self/fd/3 -> /tmp/lolcats
l-wx------. 1 sweeks sweeks 64 Dec  7 16:51 /proc/self/fd/4 -> /tmp/lolcats