shell script for in, while에대한 질문입니다.

$ X="hello world"; (for x in $X; do echo [$x]; done)
[hello]
[world]
$ X="hello world"; (IFS=$''; for x in $X; do echo [$x]; done)
[hello world]

$ echo "hello world" | (while read a b; do echo [$a]; done)
[hello]
echo "hello world" | (IFS=$''; while read a b; do echo [$a]; done)
[hello world]

$ X="hello world" | (x=($X); echo [${x[0]}])
[hello]
$ X="hello world" | (IFS=$''; x=($X); echo [${x[0]}])
[hello world]