Jon Seymour wrote:
> On Mon, Feb 16, 2009 at 10:22 AM, Paul Jarc <p...@po.cwru.edu> wrote:
>> Jon Seymour <jon.seym...@gmail.com> wrote:
>>> If the builtin echo fails it will be because the bash interpreter
>>> has suffered a catastrophic failure of some kind [ e.g. run out of
>>> memory ]. Once that has happened, all bets are off anyway.
>>
>> Probably true, but command substitution forks a separate process, so
>> that can fail for reasons external to the bash process.
>>
>> Here's another possibility:
>> CPATH=${CPATH:+$CPATH:}${#+~usr1/blah/blah}
>>
>
> Paul,
>
> Out of interest, how does one derive that outcome from the documented
> behaviour of bash? That is, which expansion rules are being invoked?
${#+~usr1/blah/blah} probably refers to $#. Strangely, this variable seems
to be defined even when not executing any function. However, in this case
"echo $#" prints "$#"! The expansion rules are exactly two:
${parameter:+word}
(http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameters,
3.5.3 Shell Parameter Expansion) and ${parameter} (3.5.3 Shell Parameter
Expansion)
-Angel
