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Re: read Built-in Parameter Behavior -- Null Byte Delimiter


From: Adam Danischewski
Subject: Re: read Built-in Parameter Behavior -- Null Byte Delimiter
Date: Tue, 19 Jan 2016 12:09:54 -0500

Right, the programs don't see those empty strings because the shell is stripping them when it parses the line. But for options, for the shell parser to strip away the empty string presumes that the user made a mistake and has needlessly/erroneously provided a useless empty string.

In the case for read -d'' very probably the user has attempted to supply the null delimiter, but read quietly takes the next argument. I think it makes sense to bump empty strings away from the option when they occur after options in the Bash interpreter parsing of the commandline.
-d''  --> -d ''

On Tue, Jan 19, 2016 at 11:49 AM, Greg Wooledge <address@hidden> wrote:
On Tue, Jan 19, 2016 at 11:39:07AM -0500, Adam Danischewski wrote:
> Bash also removes the single quotes before it hits read when the single
> quotes are attached to the delimiter option (-d'').

And in EVERY OTHER COMMAND.  This is how quotes work.  This is utterly
fundamental to bash and the entire Bourne shell syntax.

  echo ""'a'''$''""''

Is *exactly* the same as

  echo a

Echo has no way to know that you typed a and not "a" or a"" or 'a' or ....


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