bug#34816: 25.2; dired regexp fails for filenames that begin with a space

[Michael Albinus <michael.albinus@gmx.de>]

Andrew Eggenberger <andrew@lakecitygraphic.com> writes:

Hi Andrew,

> Trying to use dired-do-rename-regexp caused the following error:
>
> (file-error Renaming No such file or directory
> /Users/andrew/Public/Temp_2019/Temp_2.25.19/Tiger Pride/- 1B, Thieren,
> Addison.JPG /Users/andrew/Public/Temp_2019/Temp_2.25.19/Tiger
> Pride/Addison, Thieren.jpg)
>
> The reason for the file error is that the filename actually begins
> with
> a space character before the hyphen. It appears that the mechanism 
> used to identify filenames within dired isn't sensitive to opening
> spaces. 

It isn't as simple as it looks. Often, dired uses a command like "ls -al
--dired". This gives precise information, where file names are located
in the output, and Emacs could determine also file names starting with
spaces.

If this ls option isn't available, something like "ls -al" is
applied. From the output it isn't obvious, whether a leading space
belongs to a file name, or whether it is just a separator to the
date. One could implement heuristics (check the column other file names
start with), but this isn't implemented.

If it comes to remote file names, the situation is even worse, because
you cannot always assume a proper ls command on the remote side.

One alternative for you might to use ls-lisp.el. It doesn't apply "ls
-al", but tries to collect the needed information differently. Due to
this, dired might have a better idea about file names.

Best regards, Michael.