BASH Command substitution

[Zoltan Mate]

Dear Chet Ramey,

I have a conversation on an other bug forum, then have been directed
to here, I cannot find any documentation, why

$ echo $(echo "'alfa  beta'")
gives 'alfa beta' whith reduced space, instead of the result of the
following more logical ways:

$ echo $(echo "'alfa  beta'")
the second term suggests one parameter being substituted as
"<the output of the command>"

On the other hand, having made the substitution, one should get the
$ echo 'alfa  beta'
text to be interpreted.


So why the '-s are quoted and the spaces are not?
This strange behaviour should be mentioned in the bash manual.

Zoltan Mate
----------------------------------------- The former conversation:
--------------------------------------------
bash command substitution reduce double spaces in strings:

$ echo $(echo "'alfa  beta'")
'alfa beta'


Reproducible: Always

Steps to Reproduce:


------- Comment #1 From SpanKY 2009-12-16 19:32:24 0000 [reply] -------

the second isnt actually quoted which means you ran:
argv[] = {
    "echo"
    "'alfa"
    "beta'"
}


------- Comment #2 From ZoliM 2009-12-17 09:41:08 0000 [reply] -------

Where is emphasized the text interpreatation process in the manual?

In
$ echo $(echo "'alfa  beta'")
the second term suggests one parameter being substituted as
"<the output of the command>"

On the other hand, having made the substitution, one should get the
$ echo 'alfa  beta'
text to be interpreted.

So I motion to mark in the documentation at the Command substitution chapter
the proper interpretation logic.


------- Comment #3 From SpanKY 2009-12-17 10:32:32 0000 [reply] -------

those two examples are not equivalent.  your first snippet boils down to:
echo \'alfa  beta\'

this bugzilla isnt a forum for teaching people how to script bash.  if you want
further help, please ask on the bash mailing list, or the gentoo forums, or
some other suitable location.