Re: ${parameter+word} not documented in bash.info or bash(1)
Bob == Bob Proulx b...@proulx.com writes:
Bob [...] Let me suggest that something similar to the following
Bob addition would help here.
Bob is unset or null; omitting the colon (':') results in a
Bob test only for a parameter that is unset.
Bob Then searches on : would also find that descriptive text
Bob too.
I agree.
However, I would still suggest going further and including at least
one full example.
peace happiness,
martin
Re: ${parameter+word} not documented in bash.info or bash(1)
Paul == Paul Jarc p...@po.cwru.edu writes:
Paul Martin Schwenke mar...@meltin.net wrote:
Neither bash.info or bash(1) documents parameter expansion of
the form:
${parameter+word}
Paul It's documented, but it's easy to miss. Just before the
Paul list of parameter expansion forms is this paragraph:
PaulIn each of the cases below, word is subject to tilde
Paulexpansion, parameter expansion, command substitution,
Pauland arithmetic expansion. When not performing
Paulsubstring expansion, bash tests for a parameter that
Paulis unset or null; omitting the colon results in a
Paultest only for a parameter that is unset.
Ouch! Can I suggest that this documentation could be improved, since
it is so easy to miss and that I missed it at least 4 times when
actually looking for it? ;-)
I think the main issue is that when people use reference documentation
they tend to scan through it to find what they're looking for.
My suggestion would be to break the list of expansions before
substring expansion and insert a paragraph containing the above text.
Then, rather than necessarily listing all of the examples as the
standard does, perhaps provide a single example that compares the
effect of using the colon with the effect of excluding it.
The bash documentation is so long that I don't think adding this will
make it too long... :-)
peace happiness,
martin
Re: ${parameter+word} not documented in bash.info or bash(1)
Martin Schwenke wrote:
Paul Jarc writes:
It's documented, but it's easy to miss. Just before the
list of parameter expansion forms is this paragraph:
In each of the cases below, word is subject to tilde
expansion, parameter expansion, command substitution,
and arithmetic expansion. When not performing
substring expansion, bash tests for a parameter that
is unset or null; omitting the colon results in a
test only for a parameter that is unset.
Ouch! Can I suggest that this documentation could be improved, since
it is so easy to miss and that I missed it at least 4 times when
actually looking for it? ;-)
Let me cast a vote for this too. I know what it does but have also
found myself looking for it specifically because I am looking for
: and not colon. If the colon character ':' were mentioned in the
description I think that would make this much clearer. Let me suggest
that something similar to the following addition would help here.
is unset or null; omitting the colon (':') results in a
test only for a parameter that is unset.
Then searches on : would also find that descriptive text too.
Bob
Re: ${parameter+word} not documented in bash.info or bash(1)
Martin Schwenke mar...@meltin.net wrote:
Neither bash.info or bash(1) documents parameter expansion of the
form:
${parameter+word}
It's documented, but it's easy to miss. Just before the list of
parameter expansion forms is this paragraph:
In each of the cases below, word is subject to tilde expansion,
parameter expansion, command substitution, and arithmetic
expansion. When not performing substring expansion, bash tests
for a parameter that is unset or null; omitting the colon
results in a test only for a parameter that is unset.
paul
Re: ${parameter+word} not documented in bash.info or bash(1)
Martin Schwenke wrote:
I'm running bash 3.2.39(1)-release (under Ubuntu 8.04 (Hardy)
GNU/Linux). Neither bash.info or bash(1) documents parameter
expansion of the form:
${parameter+word}
This is different to ${parameter:+word}, is clearly implemented by
bash and is documented in the standard (The Open Group Base
Specifications Issue 6, IEEE Std 1003.1, 2004 Edition).
This may be useful:
http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_06_02
The bash documentation includes essentially the same text as the standard
describing the effect of omitting the colon in those word expansions.
Thanks for bash, it rocks... :-)
:-)
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
