[pdftex] launching programs...

[G. D. Brettschneider]

Thierry Bouche wrote:

>
>   (...) I could prefer to send a command to execute to the system directly
>   (xemacs file.tex, e.g., assuming command is on the system path) and I
>   would like to have such a feature as much OS-independant as possible (...)
>
In case you're talking about launching programs during *runtime* of the 
pdftex engine, set

  shell_escape = t

in texmf.cnf. Then define a system macro

  \def \system #1{\immediate \write 18 {#1}}

and start your experiments with something like this ( which brings a 
list of environment variables):

  \system {set > envivar.txt}
  \parindent = 0mm \par
  % Display environment variables which contain characters
  % like "$", "_", "<", "\":
  \bgroup
    % Enable linebreak after ":" and ";":
    \long \def \colon #1{%
      \def \first {#1}%
      \ifx \first \backslash :\backslash \else
      \ifx \first \slash : \slash \else
      \ifx \first \slash :\par \hskip \baselineskip \slash \else
      \ifx \first \par :\par \hskip \baselineskip \fi \fi \fi \fi}%
    \long \def \semicolon {;\par \hskip \baselineskip}%
    \catcode `\: = 13 % active
    \catcode `\; = 13 % active
    \catcode `\_ = 12 % other
    \catcode `\$ = 12 % other
    \catcode `\< = 0 % escape
    \catcode `\\ = 12 % other
    % Now use "<" instead of "\" as escape character,
    % and don't read linebreak as whitespace:
    <obeylines
    % Enable linebreak after ":" and ";":
    <def <backslash {\}%
    <def <slash {\}%
    <let ; = <semicolon
    <let : = <colon
    % Load and display generated file:
    <input envivar.txt
    <par <vfill
  <egroup

In practice, since system commands usually are given different names and 
options on DOS/Windows and UNIX/Linux, you may have to write both a 
batch file and a shell script with the same base name in order to 
execute an OS-independent command.

Regards,

Gerolf