Re: EOF does not work in echo

[Cai Qian]

Hi,

On 5/26/06, Chris F.A. Johnson <cfajohnson@gmail.com> wrote:
> On 2006-05-25, Cai Qian wrote:
> > Hi,
> >
> > echo -e "hello \004world" | cat
> >
> > will print out
> >
> > hello world
>
>     As it should.
>
> > echo -e "hello \004world" | cat > /dev/null
> >
> > will print out nothing
>
>     Of course: you sent it all to /dev/null.
>
> > It suggests that "cat" has not seen EOF (004) generated by echo.
>
>     Try piping it to od or hexdump:
>
> $ echo -e "hello \000world" | hexdump -C
> 00000000  68 65 6c 6c 6f 20 00 77  6f 72 6c 64 0a           |hello .world.|
> 0000000d
>
>     Do you expect cat to stop printing after \004? It won't; it will
>     print all characters. If it didn't, it would be of no use for
>     concatenating binary files.

It seems nobody will stop reading when see EOF.

 echo -e "hello \004world" | { read i; echo i = $i; }

It would be nice if we can manually generate a EOF to terminate a
program's reading from STDIN. Therefore, we can do something like,

unset i; unset j; echo -e "hello \004world" | { read i; echo i = $i;
read j; echo j = $j;}

i = hello
j = world

Qian