LISP: Problem with vl-filename-mktemp prefix

Roy Klein Gebbinck

Does anybody know why the default prefix "$VL" used by (vl-filename-mktemp) gets stripped from the file name in this case?:
[code]: (setq name (vl-filename-mktemp))
"/home/roy/$VL~~00a"
: (command "_.shell" (strcat "ls > " name))[/code]
The result is this file:
/home/roy/~~00a

The problem can be avoided by using something like:
(vl-filename-mktemp "abc")

Note: The code below works without any problems. So the prefix "$VL" is allowed on LInux.
[code](defun C:Temp_file ( / file)
  (setq file (vl-filename-mktemp))
  (setq file (open file "w"))
  (write-line "test" file)
  (close file)
)[/code]

Knut Hohenberg

Roy,
The $ sign is a reserved char in the shell, and it is not enough to put it into quotes to prevent it from getting interpreted. From the bash man page:

... The characters $ and ` retain their special meaning within double quotes. ...

So you have to escape it with a leading backslash (\$) to use it in file names etc.

Roy Klein Gebbinck

Thanks for clearing that up Knut. I guess I am still a novice when it comes to Linux.

Torsten Moses

Dear Roy, Dear Knut,

thanks for sharing !
So it seems a good idea to refactor (vl-filename-mktemp) fucntion, not to use that "$VL" prefix,
but to use a slightly different one, not using such special characters.

I will implement, and one of next BricsCAD versions should have it.

Many greetings !