Hi, Kevin. I don't have a solution, but I found that interesting, so did some experiments:
$ bash --version bash --version GNU bash, version 3.1.0(1)-release (i486-pc-linux-gnu) Copyright (C) 2005 Free Software Foundation, Inc. $ echo foo | read a; echo $a returns empty variable a whole lot of options on read like -t 1, -n 3 and so on don't improve that, neither does echo -e 'foo\n\n\n' or similar things. -- $ echo foo > temp;read a < temp; echo $a returns foo, but creates and uses a file in between $ mkfifo myfifo creates a named pipe -- terminal1$ echo foo > myfifo; read a < myfifo; echo $a just keeps working and doesn't return, but if I do terminal2$ cat myfifo in another shell, I see that foo has actually gone there, and one moment later, the whole thing returns an empty $a [...] -- $ echo -e "foo\n\n" > myfifo; read -n 2 a < myfifo; echo $a returns: bash: myfifo: interrupted during an operating system call (translation) and an empty $a -- $ echo -e foo\n\n > myfifo & read -n 2 a < myfifo; echo $a [1] 7487 bash: myfifo: Unterbrechung während des Betriebssystemaufrufs (same message) -- $ echo foo > myfifo & sleep 1; read a < myfifo; echo $a [3] 7492 foo Surprise, this one works. So far so good: echo does not return from writing into the pipe before the pipe is not read read does not start reading from the pipe before echo has not stopped -- now, trying: $ echo foo > myfifo & [1] Done echo foo >myfifo $ read a < myfifo $ echo $a this one works as well. -- Now, using *two* shells again: terminal1$ echo foo > myfifo remains pending until... terminal2$ cat myfifo foo returns foo while echo... on shell a returns. -- terminal1$ echo foo > myfifo remains pending until... terminal2$ read a < myfifo; echo $a returns empty line on shell b while echo... on shell a returns. It doesn't work with terminal1$ echo foo > myfifo & either. -- I don't have the in depth knowledge to interpret it, but I find it interesting and surprising. Best wishes, js
From: "Kevin B. McCarty" <[EMAIL PROTECTED]> Could someone tell me why the following works in zsh but not in bash/posh/dash? benjo[3]:~% echo foo bar baz | read a b c benjo[4]:~% echo $a $b $c foo bar baz If I try the same with bash (or other sh-compatible shells), the variables $a $b and $c are unset. From the bash man page:
>[..]
So "read" claims to read from the standard input, but it doesn't actually seem to happen when a pipe is involved.
-- ------------------------------------------------------------------- Dr. med. Jörg M. Sigle http://www.ql-recorder.com +49-5527-846-535 http://www.jsigle.com Have a lovely day... +49-7043-950-6864
