"Linde, Evan" <eli...@okstate.edu> writes:
> In a loop constructed like `... | while read ...`, changes to
> variables declared outside the loop only have a loop local
> scope, unlike other "while" or "for" loops.
Yeah, that's a gotcha. But it's a general feature of *pipelines*,
documented in
Each command in a pipeline is executed as a separate process (i.e., in
a subshell). See COMMAND EXECUTION ENVIRONMENT for a description of a
subshell environment. If the lastpipe option is enabled using the
shopt builtin (see the description of shopt below), the last element of
a pipeline may be run by the shell process.
To circumvent that, I've sometimes done things like
exec 3<( ... command to generate stuff ... )
while read VAR <&3; do ... commands to process stuff ... ; done
exec 3<-
You may be able to condense that to
{
while read VAR <&3; do ... commands to process stuff ... ; done
} <( ... command to generate stuff ... )
Changing {...} to (...) won't work, because (...) again executes things
in a subshell.
(But don't trust that code without checking it!)
Dale
