read unter RedHat AS

[Achim Dreyer]

On Thu, 14 Aug 2003, Achim Dreyer wrote:
> On Wed, 13 Aug 2003, Michael Schneider wrote:
> > On Wed, 13 Aug 2003 21:24:02 +0200, Jan-Benedict Glaw wrote
> > > echo blah fasel | while read i j; do
> > > 	# Hier sind die Variablen gesetzt
> > > 	echo $i
> > > 	echo $j
> > > done
> > > # Ab hier nicht mehr
> > 
> > jetzt wo du es sagst ..
> > mist dann muss ich alles umbauen ;-(
[..]
> .. in der alten Original Bourne Shell ging das auch noch anders (über 
> umbiegen von filedescriptoren), aber bei der bash muß man immer 
> filedescriptoren an dateien hängen.


see FAQ of comp.unix.shell (Ted Timar), section 3.8:
--snip--
      In historic (and P1003.2 conformant) implementations you can use
      the following `trick' to get around the redirection problem:

        foo=bar

        # make file descriptor 9 a duplicate of file descriptor 0 (stdin);
        # then connect stdin to /etc/passwd; the original stdin is now
        # `remembered' in file descriptor 9; see dup(2) and sh(1)
        exec 9<&0 < /etc/passwd

        while read line
        do
                # do something with $line
                foo=bletch
        done

        # make stdin a duplicate of file descriptor 9, i.e. reconnect
        # it to the original stdin; then close file descriptor 9
        exec 0<&9 9<&-

        echo "foo is now: $foo"

      This should always print ``foo is now: bletch''.
--snip--


Regards,
Achim Dreyer
--
A. Dreyer, Senior SysAdmin (UNIX&Network) / Internet Security Consultant