Re: [Help-bash] How to print a bash variable in the most succinct way?

[Chet Ramey]

On 8/16/16 9:40 PM, Peng Yu wrote:
> 
> 
> On Tuesday, August 16, 2016, Chet Ramey <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     On 8/16/16 9:21 PM, Peng Yu wrote:
>     > On Tue, Aug 16, 2016 at 8:13 PM, Chet Ramey <address@hidden
>     <javascript:;>> wrote:
>     >> On 8/16/16 4:54 PM, Peng Yu wrote:
>     >>> On Tue, Aug 16, 2016 at 2:56 PM, Chet Ramey <address@hidden
>     <javascript:;>> wrote:
>     >>>> On 8/16/16 3:21 PM, Peng Yu wrote:
>     >>>>
>     >>>>>
>     >>>>> How to only generate variables that are modifiable (i.e., not
>     readonly)?
>     >>>>
>     >>>> Generate a list of all variables.  Generate a list of readonly
>     variables.
>     >>>
>     >>> How to generate a list of the names of the readonly variables?
>     >>> `readonly` will print both the names and their values. I will run into
>     >>> the same problem when there are $'\n' in their values.
>     >>
>     >> Use the toolset.
>     >>
>     >> readonly -p | grep = | sed 's|^declare.*
>     \([[:upper:][:lower:]_]*\)=.*$|\1|'
>     >> readonly -p | awk '$0 ~ "declare.*" {print $3}' | sed
>     >> 's|[^[:upper:][:lower:]_].*$||'
>     >
>     > These commands won't work robustly as shown below.
> 
>     Then modify them.  You have to do some of the work yourself here.
> 
> 
> It will requires a parser to parse the result if one wants it to robust. It
> can require quite some work.

A one-character change to the awk version of the command will work with
bash-4.4.

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