stdin in scripts

-.sh

#!/bin/sh

F=/dev/stdin
while : ; do
    ls -al "$F" 2>/dev/null
    F=$( readlink "$F" )
    [ -z "$F" ] && break
done

1

$ sh ~/-.sh
lrwxrwxrwx 1 root root 15 Oct 18 12:18 /dev/stdin -> /proc/self/fd/0
lrwx------ 1 saji saji 64 Oct 22 15:44 /proc/self/fd/0 -> /dev/pts/35
crw--w---- 1 saji tty 136, 35 Oct 22 15:44 /dev/pts/35

2

$ sh ~/-.sh < ~/foo
lrwxrwxrwx 1 root root 15 Oct 18 12:18 /dev/stdin -> /proc/self/fd/0
lr-x------ 1 saji saji 64 Oct 22 15:44 /proc/self/fd/0 -> /home/saji/foo
-rw-r----- 1 saji saji 6 Oct 22 15:18 /home/saji/foo

3

$ cat ~/foo | sh ~/-.sh
lrwxrwxrwx 1 root root 15 Oct 18 12:18 /dev/stdin -> /proc/self/fd/0
lr-x------ 1 saji saji 64 Oct 22 15:44 /proc/self/fd/0 -> pipe:[4470786]