Re: weird echo behaviour...

[Andreas Schwab]

"Alfred M. Szmidt" <address@hidden> writes:

> Could someone explain the following behaviour for me?  Because I sure
> do not understand it.

This has nothing to do with echo and everything to do with the shell.

> address@hidden:/tmp/foo$ touch 1 2 3 4 5
> address@hidden:/tmp/foo$ foo=`ls`

The value of foo now contains a bunch of newlines, among others.

> address@hidden:/tmp/foo$ /bin/echo $foo
> 1 2 3 4 5

Unquoted variable substitution splits on whitespace and /bin/echo receives
5 arguments, each of which is echoed separated by a single space.  This is
equivalent to:

$ /bin/echo 1 2 3 4 5

> address@hidden:/tmp/foo$ /bin/echo "$foo"
> 1
> 2
> 3
> 4
> 5

Quoted variable substitution does not split and preserves all whitespace
as is.  The (single) argument is echoed unchanged.  This is equivalent to:

$ /bin/echo "1
2
3
4
5"

> address@hidden:/tmp/foo$ foo='1 2 3 4 5'

Now foo contains a completely different value.

> address@hidden:/tmp/foo$ /bin/echo $foo
> 1 2 3 4 5

Still splitting on whitespace, still passing 5 arguments, same as first
example above.

> address@hidden:/tmp/foo$ /bin/echo "$foo"
> 1 2 3 4 5

Still no splitting, still passing one argument.  This is equivalent to:

$ /bin/echo "1 2 3 4 5"

Andreas.

-- 
Andreas Schwab, SuSE Labs, address@hidden
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."