$ coproc WC { wc; }
[1] 10038

$ ps
  PID TTY          TIME CMD
 9926 pts/3    00:00:00 bash
10038 pts/3    00:00:00 bash
10039 pts/3    00:00:00 wc
10040 pts/3    00:00:00 ps

$ ls -lgo /proc/{$$,10038,10039}/fd/
/proc/10038/fd/:
total 0
lr-x------ 1 64 Mar 14 02:29 0 -> pipe:[81214]
l-wx------ 1 64 Mar 14 02:29 1 -> pipe:[81213]
lrwx------ 1 64 Mar 14 02:28 2 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:29 255 -> /dev/pts/3

/proc/10039/fd/:
total 0
lr-x------ 1 64 Mar 14 02:29 0 -> pipe:[81214]
l-wx------ 1 64 Mar 14 02:29 1 -> pipe:[81213]
lrwx------ 1 64 Mar 14 02:28 2 -> /dev/pts/3

/proc/9926/fd/:
total 0
lrwx------ 1 64 Mar 14 02:26 0 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:26 1 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:25 2 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:26 255 -> /dev/pts/3
l-wx------ 1 64 Mar 14 02:26 60 -> pipe:[81214]
lr-x------ 1 64 Mar 14 02:26 63 -> pipe:[81213]

$ echo ${WC[@]}
63 60

$ exec {WC[1]}>&-
[1]+  Done                    coproc WC { wc; }

$ ps
  PID TTY          TIME CMD
 9926 pts/3    00:00:00 bash
10042 pts/3    00:00:00 ps

$ echo ${WC[@]}

$ ls -lgo /proc/$$/fd/
total 0
lrwx------ 1 64 Mar 14 02:26 0 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:26 1 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:25 2 -> /dev/pts/3
lrwx------ 1 64 Mar 14 02:26 255 -> /dev/pts/3