Run something in current context of shell, postprocessing stdout&stderr without disturbing return code

_catch.inc

# Redirect lines of stdin/stdout to some other function
# outfn and errfn get following arguments
# "cmd args.." "one line full of output"
: catch outfn errfn cmd args..
catch()
{
local ret o1 o2 tmp
tmp=$(mktemp "catch_XXXXXXX.tmp")
mkfifo "$tmp.out"
mkfifo "$tmp.err"
pipestdinto "$1" "${*:3}" <"$tmp.out" &
o1=$!
pipestdinto "$2" "${*:3}" <"$tmp.err" &
o2=$!
"${@:3}" >"$tmp.out"  2>"$tmp.err"
ret=$?
rm -f "$tmp.out" "$tmp.err" "$tmp"
wait $o1
wait $o2
return $ret
}

: pipestdinto cmd args..
pipestdinto()
{
local x
while read -r x; do "$@" "$x" </dev/null; done
}

STAMP()
{
date +%Y%m%d-%H%M%S
}

# example output function
NOTE()
{
echo "NOTE `STAMP`: $*"
}

ERR()
{
echo "ERR  `STAMP`: $*" >&2
}

catch_example()
{
# Example use
catch NOTE ERR find /proc -ls
}