[ILUG] Bash using locally scoped vars inside while loop.

[Kevin O' Riordan]

> me> when I use a while loop to read piped input, bash seems to use locally
> me> scoped variables instead of assigning to global variables in that

Padraig> ... when you pipe to a control statement in sh/bash ... it runs
Padraig> that control statement in a subshell.

Ah right.  That confused the hell out of me, I thought it was some
scoping problem (bash seems to have local vars, but I've never used
them).  Pretty surprising feature !


Achim> to get around this you can use stdin redirection with
Achim> 	exec 1<file
Achim> as this happens only with redirected/piped input not with stdin.

Steve> ... i'll just suggest a way around it:
Steve> for i in `seq 1 3`; do
Steve>        blah
Steve> done

I wouldn't have thought of the first workaround at all, but I would've
worried about using the second on large outputs, ie. `cat 5mb_file`
instead of `seq 1 3`.  In a test I just ran, bash handled `cat 5_mbfile`
ok (took over 10 mins though), so I'll use that, I guess.

thanks to all !
-kev

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