Re: sed with Variable Substitution in the command

[alex xmb sw ratchev]

oh see , sed .. nm , thxx ..

On Thu, Sep 26, 2024 at 6:53 PM alex xmb sw ratchev <fxmbsw7@gmail.com>
wrote:

> sorry .. where is $11 and error ?
>
> On Thursday, September 26, 2024, Wiley Young <wyeth2485@gmail.com> wrote:
>
>> From: Steve Matzura
>>   "... Variable substitution has always been a problem for me because
>> there
>> doesn't seem to be a single hard-and-fast rule--sometimes the variable is
>> quoted, sometimes it's wrapped in braces...."
>>
>>
>> Regarding braces, it's always permissible to surround a parameter name in
>> braces, meaning that adding braces won't cause an error. On the other
>> hand,
>> there are numerous situations where omitting braces would cause an error.
>>
>> Okay         ??
>> ====     ====
>> "${foo}"
>>             "$foo" is okay
>> "${bar##_*}"
>>             "$bar##_*" is an error
>> "${1}"
>>             "$1" is okay
>> "${11}"
>>             "$11" is an error
>> "${array[1]}"
>>              "$array[1]" is an error
>>
>> I use the term "error" loosely to mean, unintended effects will occur.
>>
>> Braces are also used for other things as well: compound commands, function
>> definitions, and brace expansion among others. Each of these are something
>> else, though.
>>
>> Just always using braces _is_ extra typing. Some might say that it's less
>> _readable._ Still, doing so lets users more errors while remembering fewer
>> rules.
>>
>> Wiley
>>
>