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Re: [Help-bash] for File in Folder_Variable_Name Expansion

From: Chris Down
Subject: Re: [Help-bash] for File in Folder_Variable_Name Expansion
Date: Mon, 16 Dec 2013 23:06:59 +0800
User-agent: Mutt/1.5.22 (2013-10-16)

On 2013-12-16 04:33:58 -0900, Roger wrote:
> This was the crux of my problem here.  Although the whitespace/space within 
> the 
> folder (or filename, or path) was an initial issue until I used a wildcard 
> (or 
> globbing, or "*", or "?") for substitution of the whitespace.
> This main issue of "for FILE in /PATH/*.jpg" was really difficult, as I 
> always 
> prefer using global variables instead of statically assigned data.  (As most 
> others likely do too.)  I was thinking this should just work when written as 
> "for FILE in /PATH/*.jpg" as it appeared syntactically correct compared to 
> other variable usage or other variable assignments.  (ie. printf 
> "${HOME}/file.jpg")

The reason is the quoting, nothing else. When quoted, "?" has no special

> About the only question remaining, is why some bash commands (or functions) 
> do 
> not uniformly accept variable expansion similar to using within printf or 
> echo.  
> (ie. printf "${HOME}/file.jpg")  But suspect every command handles expansion 
> based on each commands programmed method of handling a variable expansion.

Bash is the one doing variable expansion, not the commands, so I'm not
sure what you mean. If you do foo "$bar", and bar is "baz", then "foo"
only ever sees "baz", it never knows that you passed a variable in the
first place.

Can you give an example of why you think this?

> Looking back over the Bash Manual, I see printf or echo listed under the 
> BUILTIN COMMANDS" category, and the "for" command categorized under "SHELL 
> GRAMMAR > Pipelines".  As such, each category of commands, handles expansion 
> differently?

No, they don't; they handle expansion in the same way (in that they
don't, bash does it separately). If you could give a minimal example of
what made you think this, that would be helpful.

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