Command substitution / word splitting question

[Binarus]

Hi all,

the bash reference manual states in chapter 3.5.7: "The shell scans
the results of parameter expansion, command substitution, and
arithmetic expansion that did not occur within double quotes for word
splitting.". I thought I had understood this, but then came across a
problem.

Let's look at a very simple script:

echo 'line1' > file
echo 'line2' >> file
echo $(cat file)

When you run this script, you get the following output:

line1 line2

This is like expected: The output of "cat file" contains at least one
embedded newline; since the command substitution does not take place
within double quotes, the newline is replaced by a space when the
result of the expansion is word-splitted.

The script

echo 'line1' > file
echo 'line2' >> file
echo "$(cat file)"

gives the output

line1
line2

which is also the expected one because now the word splitting does not
occur after the command substitution because of the double
quotes;thus, the newline is conserved and the output is two lines.

So far, so good. The problem comes up if I am working with variables
that store the result of the command substitution.

The script

echo 'line1' > file
echo 'line2' >> file
RESULT=$(cat file)
echo "$RESULT"

gives the following output:

line1
line2

I don't understand why: the command substitution $(cat file) is not
within double quotes, so word splitting should be applied to the
result of the substitution and any embedded newlines should be
removed. Thus, $RESULT should contain text without newlines after line
three in the above script is executed.

But obviously, the original output of $(cat file), including embedded
newlines, has made it into $RESULT. Otherwise, the output would be
just one line and not two.

So why does this happen? I would be grateful if someone could explain
when the word splitting is exactly taking place.

Thank you very much,

Peter