Bash Shell Parameter Expansion

[tolugboji]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐

On Saturday, October 9th, 2021 at 11:09 PM, Alex fxmbsw7 Ratchev 
<fxmbsw7@gmail.com> wrote:

> you may be not reading the man bash to your version ?

I am reading from the site which should be the latest descriptions
https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html

> a means b
>
> -   means str appears when var is unset ( never used yet )
>
> -   means str appears when var is set already
>
>     :- means str if unset or empty
>
>     :+ str if set or empty
>
>     .. hmm im not sure atm..

Reading more carefully, the omitting the colon case is described.  There is a 
lot
one can do with parameter expansion.

Have seen that fontify=${st:+"no"} results in an empty value for fontify (when 
st is unset),
even when fontify was previously assigned.

>     On Sun, Oct 10, 2021, 00:58 tolugboji tolugboji@protonmail.com wrote:
>
> > Some bash implementations mention ${PARAMETER-WORD} and
> >
> > ${PARAMETER+WORD}. But these are not mentioned
> >
> > in the gnu bash manual? Is this because they are not implemented in gnu
> >
> > bash?