ansaurus

Question

Answer 1

+2 A:

You cannot mix exec and pipes that way. It seems what you need is a process substitution:

$ exec 3< <(cat /etc/hosts)
$ grep ftp <&3
209.85.41.143 ftp.archlinux.org

tokland 2010-06-02 14:39:37

Of course, this serves as a generic example, if you need only a "cat", you can write directly: "exec 3< myfile".

tokland 2010-06-02 15:53:21

Answer 2

A:

exec 3<>$0
while read -u 3 line;
do
  grep ftp $line;
done
exec 3>&-;

krico 2010-06-02 14:46:32

this makes 3 a fd of $0 file - not a pipe. See the answer.

name 2010-06-03 10:58:22

bash getting a fd of a pipe