Beginner in Mac OS X, and ADA and gtkAda: $prefix, and what bin, and home is usr/bob or OSX Users/bob

Beginner in Mac OS X, and ADA and gtkAda: $prefix, and what bin, and home is usr/bob or OSX Users/bob

[Mace Ayres]

Sorry for some beginner's questions, but.

New to Mac OSX. Various software instructions may say home directory; is that OS X  ./USERS/Me
or Unix's /usr/me:

Sometime they refer to the bin directory. Which bin?

Some instructions say $prefix .. what prefix is that?

Is this even an understandable question?

Re: Beginner in Mac OS X, and ADA and gtkAda: $prefix, and what bin, and home is usr/bob or OSX Users/bob

[Dennis Lee Bieber]

On Mon, 11 Sep 2017 16:17:51 -0700 (PDT), Mace Ayres <mace.ayres@gmail.com>
declaimed the following:

>Sorry for some beginner's questions, but.
>
>New to Mac OSX. Various software instructions may say home directory; is that OS X  ./USERS/Me
>or Unix's /usr/me:
>
>Sometime they refer to the bin directory. Which bin?
>
>Some instructions say $prefix .. what prefix is that?
>
>Is this even an understandable question?

	None of these questions are applicable to Ada itself -- they are all
dependent upon the operating system in use, so the answer is really in the
OS documentation or guide books.

	However...

Linux (UNIX) home directory is normally
		/home/{username}
and often accessible using ~

wulfraed@stretch:~$ cd ~
wulfraed@stretch:~$ pwd
/home/wulfraed
wulfraed@stretch:~$ 

	I do not know how Mac handles paths. In Linux, a leading "./" indicates
current directory (and is often used when one is trying to run a local
executable that is NOT in the search path: ./program or ./scriptfile -- for
safety, Linux will not run programs in the current directory by name only,
to avoid trojans; if someone had stuffed a virus program called, say, gcc
in your home directory, and you try to compile something by typing "gcc -o
myprog myprog.c" it will ignore the virus file and use the system gcc --
but "./gcc -o myprog myprog.c" would run the virus file )

/usr is NOT a home directory! It is a location where non-OS applications
tend to be installed...

	Normally, "bin" is likely the one at the root level of the file system
(root is a simple /): 

wulfraed@stretch:~$ ls /
bin   home            lib32       media  root  sys  vmlinuz
boot  initrd.img      lib64       mnt    run   tmp  vmlinuz.old
dev   initrd.img.old  libx32      opt    sbin  usr
etc   lib             lost+found  proc   srv   var
wulfraed@stretch:~$ 

... however, you will also find a bin under /usr

wulfraed@stretch:~$ ls /usr
bin  games  include  lib  lib32  libx32  local  sbin  share  src
wulfraed@stretch:~$ 

(sbin tends to be for privileged applications -- stuff that affects how the
system itself operates and may need root privileges to execute)

	"$prefix"		means the value of the environment variable "prefix"

wulfraed@stretch:~$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
wulfraed@stretch:~$ 

(I don't have a "prefix" variable defined, so I used the command search
path)
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/

Re: Beginner in Mac OS X, and ADA and gtkAda: $prefix, and what bin, and home is usr/bob or OSX Users/bob

[Georg Bauhaus]

Dennis Lee Bieber <wlfraed@ix.netcom.com> wrote:
> On Mon, 11 Sep 2017 16:17:51 -0700 (PDT), Mace Ayres <mace.ayres@gmail.com>
> declaimed the following:
> 
>> Sorry for some beginner's questions, but.
>> 
>> New to Mac OSX. Various software instructions may say home directory; is
>> that OS X  ./USERS/Me
>> or Unix's /usr/me:
>> 
>> Sometime they refer to the bin directory. Which bin?
>> 
>> Some instructions say $prefix .. what prefix is that?
>> 
>> Is this even an understandable question?
> 
> 	None of these questions are applicable to Ada itself -- they are all
> dependent upon the operating system in use, so the answer is really in the
> OS documentation or guide books.
> 
> 	However...
> 
> Linux (UNIX) home directory is normally
> 		/home/{username}
> and often accessible using ~
> 
> wulfraed@stretch:~$ cd ~
> wulfraed@stretch:~$ pwd
> /home/wulfraed
> wulfraed@stretch:~$ 
> 
> 	I do not know how Mac handles paths. 

MacOS is mostly a BSD Unix with a different kernel,
a different graphics system and some frameworks added
to support these.

$ echo $HOME

in a terminal window will show where the home
directory is.



> /usr is NOT a home directory! It is a location where non-OS applications
> tend to be installed...
> 

Unix System Resources is abbreviated to become
"usr".

The directory has programs that are
(a) installed with Unix itself, typically command line
   utilities 
(b) could be shared by several local machines in a
   traditional Unix network installation 

$ man hier 

in a terminal window should explain the file system 
hierarchy.


> 
> 	"$prefix"		means the value of the environment variable "prefix"

It usually refers to a path setting in a configuration 
file used in compiling a larger program.

Re: Beginner in Mac OS X, and ADA and gtkAda: $prefix, and what bin, and home is usr/bob or OSX Users/bob

[Simon Wright]

Mace Ayres <mace.ayres@gmail.com> writes:

> New to Mac OSX. Various software instructions may say home directory;
> is that OS X ./USERS/Me
> or Unix's /usr/me:

It's wherever you get to when you log in! (also, the value of the HOME
environment variable). Mine, on macOS, is /Users/simon

> Sometime they refer to the bin directory. Which bin?
>
> Some instructions say $prefix .. what prefix is that?

When a Unix-style application is installed, all its components will be
under some directory.

System utilities will be under /usr normally, and the layout is fairly
standard: /usr/bin, /usr/include, /usr/lib etc.

Non-system utilities should be somewhere else, not least so that the
base system is still usable and can still be upgraded.

A typical place would be under /usr/local. But if you use just this, you
can end up with different utilities clashing; and you can't easily
remove a utility that you no longer need (I realise that package
managers such as RPM, aptitude, macports & homebrew achieve this too).

As far as I can remember, GNAT GPL wants to install under
/usr/local/gnat; I don't like this, because I want to keep different
versions on my machine. On Windows, GNAT caters to this by installing
under C:\GNAT\2017 for example.

So, I install GNAT GPL under /opt/gnat-gpl-2017 etc and FSF GCC under
/opt/gcc-7.1.0 etc. (the /opt comes from, I think, Solaris).

The layout of the compiler under that directory is the same, so it's
handy to have a way of referring to that directory. $prefix is that way!

That name is used because most Unix build tools (I mean, the tools for
building the application) use an environment variable $prefix for this
purpose.

But, it's only a handy name for "wherever you installed the application"
- there's no actual variable involved.