interprocess-communication-files

#!/bin/bash
# process 1:
$ mkdir /tmp/anything               # create entry
$ exec 42> /tmp/anything/42         # open write on 42
$ echo "message here" >&42          # write message to 42
$ exec 42>&-                        # close write 42

# process 2:
$ exec 42< /tmp/anything/42         # open read on 42
$ cat <&42                          # read from 42 and pipe to cat
$ message here
$ exec 42<&-                        # close read 42