Re: [Help-bash] confusion of shell's new option compat41

[Chet Ramey]

On 1/16/13 9:21 PM, MaShimiao wrote:
> On 01/17/2013 03:42 AM, Chet Ramey wrote:
>> On 1/16/13 1:06 PM, Ma Shimiao wrote:
>>> According to changelog and manpage, I find compat as a new option is added.
>>> I have read manpage for many times. But I actually can't find out what it
>>> affects.
>>> And I don't understand what special character means.
>>>
>>> ManPage as follow:
>>> compat41
>>>              If set, bash, when in posix mode, treats a single quote in
>>> a dou‐
>>>              ble-quoted  parameter expansion as a special character. 
>>> The sin‐
>>>              gle quotes must match (an even number) and the characters
>>> between
>>>              the single quotes are considered quoted.  This is the
>>> behavior of
>>>              posix mode  through  version  4.1.   The  default  bash 
>>> behavior
>>>              remains as in previous versions.
>>>
>>> Could someone give me a example shows how to use compat41?
>> Look at what a bash-4.2 instance running in Posix mode does with this:
>>
>> echo "${HOME+'foo}"
>>
>> with and without compat41 enabled.
> I test in Fedora16 and bash-4.2.28. there is nothing difference.

That's actually a different problem -- the logic in bash-4.2 is broken for
setting the compat41 option.  It's fixed in the development version (which
is what I was testing on):

$ ./bash ./x25
4.3.0(21)-devel
'bar
./x25: line 10: unexpected EOF while looking for matching `''
./x25: line 11: syntax error: unexpected end of file
$ cat x25
echo $BASH_VERSION

set -o posix
foo=bar

shopt -u compat41
echo "${HOME+'$foo}"

shopt -s compat41
echo "${HOME+'$foo}"


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/