Re: BASH 4.4 mapfile/readarray/read builtins mis-behaving with pipe

[Steven Penny <svnpenn@gmail.com>]

On Sun, 15 Jul 2018 19:01:21, BloomingAzaleas wrote:
> CASE:
> echo multi-line_arg | read foo
> cat multi-line_unix_fmt_file | read foo
>  =C2=A0RESULT:
> Fail with variable foo null or unset
>
> CASES: left chev re-directions
> mapfile < some_unix_fmt_file
> mapfile <<END multi-line_here_doc
> read < some_unix_fmt_file
> read <<END multi-line_here_doc
> RESULT:
> Work as expected
>
> CASES: mapfile or read in a sub-shell
> echo multi-line_arg | ( mapfile ; stuff )
> echo multi-line_arg | ( read foo; stuff )
> RESULT:
> Work as expected.=C2=A0 However, since mapfile/read result vars are=20
> not accessible in parent shell context, can force a notable=20
> re-structuring of a script to use sub-shells.

no mis-behaving: this is intended behavior - you yourself have given
workarounds: either redirect output to a file that can be later read, or pipe to
command grouping ala {} or () and read stdin from inside the subshell

im not sure what you are asking here - it seems you have a grasp already of the
"problem" and "solution" - so nothing more needs to be said really, as nothing
needs to be fixed - another option is "lastpipe"

http://mywiki.wooledge.org/BashFAQ/024


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