mailing-list for TeXmacs Users

["Enrique Perez-Terron" <address@hidden>]

On Thu, 23 Jun 2011 07:51:07 +0200, El.Douwen <address@hidden> wrote:

> I have installed maxima at the place i install all the aplications in os  
> X : that is to say ... the folder /Applications
> i understand that terminal does not find maxima, and so, you explain  
> that texmacs can not find something that terminal doesn't find. ok
> i don't realy see how the computer interprets the command "maxima" in  
> the terminal. I have an application given with mac os X and called  
> "textedit". If in type "textedit" or "Textedit" in the os X terminal, it  
> says "command not found". I deduce from this that there is not a  
> terminal command corresponding to every os X application.


"There is not a terminal command corresponding to every os X application"

Hey, are you missing this little piece of information?

The "terminal" is really two programs. The first one is the terminal  
proper, which just draws the terminal window and the text within it,  
handles the scrollbars and remembers what text to show when you use the  
scrollbars. The terminal also gathers key-presses and sends them on to the  
second program.

The second program is a "shell". You can install different shells on a  
system, this is really just a program like any other. A shell knows of a  
few commands, but if you write a command the shell does not recognize, the  
shell assumes there is a file somewhere of that name. So if you write  
"maxima ding dong", the shell looks at the first word, "maxima", and then  
searches the disk for a file called "maxima". If it finds one, it asks the  
OS to load it as a program, and run it.

(The additional words "ding dong" or whatever you write, are passed along  
to the new program, and will perhaps be interpreted by that program, in  
whatever way it pleases. Often the additional words are file names that  
the program is supposed to read or write. The shell does not care, it just  
passes these words along.)

So there really is a "terminal command" for every executable file in your  
system!

And every "os X application" is an executable file somewhere on your disk.

Only that the shell does not look in absolutely all folders to find the  
named executable file.

All running programs on the system have each a list of strings called "the  
environment". Each string consists of a unique name, an equal sign, and  
some more text which is the "value" corresponding to that name. Whenever  
one program starts another, the second program inherits this list from the  
parent program, except as the parent first modifies it if required.  
Remember that no program is started just by you. When you start a program,  
you do so using the mouse or whatever, and there is a program already  
running that monitors your mouse movements and starts your program as you  
indicate. That already-running program supplies an "environment" to the  
program you start. And no, that already-running program is not just "the  
OS X", it is a different kind of shell that the OS X starts when you log  
in. A shell that does not use command lines but rather mouse gestures and  
keyboard shortcuts. So the ultimate source of the environment strings is  
the primordial login shell, that reads the initial environment from  
somewhere, or even earlier in the system that handles the login procedure.

Among the conventional elements of the environment there is a string  
"PATH=.....". The value part of this variable is used by the shell and by  
almost every other program as well, to determine in what folders to look  
if you supply a program name without specifying the folder in which it  
resides.

But you may specify the folder name, like this (but translate this to OS X  
conventions, I don't have a mac):
"/folder/subfolder/maxima ding dong"

In this case the first part of the command begins with a "/", which is the  
Unix/Linux convention for the root of the file system. On Windows the  
equivalent would be like "C:\folder\subfolder\maxima", and on windows the  
shell will likely also append ".bat", ".exe", ".com", and a few other  
extensions and try each in turn. The OS X conventions may differ.

When the file name contains folder separators ("/" in Unix/Linux, ":" in  
older Macs, don't know for OSX) then the shell does not use the PATH  
environment variable to determine where to look for the specified file. It  
uses the given string as is.

So, as others here have indicated, you need to teach your Mac where to  
find the "maxima" executable. First locate the actual folder where the  
file resides. Then ask around and figure out how to add this folder name  
to the PATH variable that the system passes around to the programs. This  
may be different in different OSes. Windows keeps an initial environment  
in the registry. If the shell in your terminal window is "bash" or  
anything related, the shell reads a startup file, which you can edit. Add  
a line PATH="$PATH:/folder/subfolder"
but adapt this to the applicable conventions for your shell and OS X

By the way, the standard mouse-driven shell in Windows (and perhaps also  
in OS X) does not often use the PATH variable, because when you  
double-click an icon on the screen, that icon contains a complete  
/folder/file path specification. Which is why people can use the computer  
without knowing about the PATH variable.

-Enrique