/usr/bin/rmic -- why?

[Joel]

What are jar, rmiregistry, and who knows what else doing in /usr/bin ?

I know that everyone just shoves /usr/local/java/sdk/bin (or whatever)
in at the top of $PATH, but I can think of several very good reasons
that is not a good idea. So if there's a good reason, I'd like some
feedback before I post a bug on this.

--
Joel Rees   
digitcom, inc.   株式会社デジコム
Kobe, Japan   [phone]
** http://www.ddcom.co.jp **

[Rahul Sundaram]

On Fri, 18 Feb 2005 18:52:58 +0900, Joel  wrote:
> What are jar, rmiregistry, and who knows what else doing in /usr/bin ?

they are java related packages. they might have been installed by
default. if you dont want remove them. this is not a bug

[James Wilkinson]

Joel wrote:
> What are jar, rmiregistry, and who knows what else doing in /usr/bin ?

$ ls -l /usr/bin/rmiregistry /usr/bin/jar
lrwxrwxrwx  1 root root 21 Feb 15 20:37 /usr/bin/jar -> /etc/alternatives/jar
lrwxrwxrwx  1 root root 29 Feb 15 20:37 /usr/bin/rmiregistry -> /etc/alternatives/rmiregistry

They're symlinks into the Red Hat alternatives scheme.
man 8 alternatives says:

It is possible for several programs fulfilling  the  same  or  similar
       functions  to  be  installed on a single system at the same time.  For
       example, many systems have several text  editors  installed  at  once.
       This  gives  choice  to  the users of a system, allowing each to use a
       different editor, if desired, but makes it difficult for a program  to
       make a good choice of editor to invoke if the user has not specified a
       particular preference.

The alternatives system aims to solve this problem.  A generic name in
       the  filesystem is shared by all files providing interchangeable func-
       tionality.  The  alternatives  system  and  the  system  administrator
       together  determine  which  actual  file is referenced by this generic
       name.  For example, if the text editors  ed(1)  and  nvi(1)  are  both
       installed  on  the  system,  the  alternatives  system  will cause the
       generic name /usr/bin/editor to refer to /usr/bin/nvi by default.  The
       system  administrator  can  override  this  and  cause  it to refer to
       /usr/bin/ed instead, and the alternatives system will not  alter  this
       setting until explicitly requested to do so.

So they allow you to have a number of Java virtual machines, and easily
swap from one to another.

James.

[Matthew Saltzman]

On Fri, 18 Feb 2005, Rahul Sundaram wrote:
> On Fri, 18 Feb 2005 18:52:58 +0900, Joel  wrote:
> > What are jar, rmiregistry, and who knows what else doing in /usr/bin ?
>
> they are java related packages. they might have been installed by
> default. if you dont want remove them. this is not a bug

$ ls -l /usr/bin/jar
lrwxrwxrwx  1 root root 21 Feb 11 11:35 /usr/bin/jar -> /etc/alternatives/jar

The Jpackage-style Java installs (including the gcj one included in FC3)
use the alternatives(8) system to manage simultaneous installation of 
multiple versions.

[Joel]

(Apologies for the cross-post.)

I asked
> > What are jar, rmiregistry, and who knows what else doing in /usr/bin ?
> >
> > I know that everyone just shoves /usr/local/java/sdk/bin (or whatever)
> > in at the top of $PATH, but I can think of several very good reasons
> > that is not a good idea. So if there's a good reason, I'd like some
> > feedback before I post a bug on this.

Rahul explained
> they are java related packages. they might have been installed by
> default. if you dont want remove them. this is not a bug

and James added
> They're symlinks into the Red Hat alternatives scheme.
> man 8 alternatives says:
>    [...]
>
> So they allow you to have a number of Java virtual machines, and easily
> swap from one to another.

and then Matthew clarified
> The Jpackage-style Java installs (including the gcj one included in FC3)
> use the alternatives(8) system to manage simultaneous installation of 
> multiple versions.

Okay, I'll dig into the alternatives man page, although I really didn't
want to know about that. Don't plan on using it.

But I did not install any java at all when I installed Fedora. There was
no javac in the same place. Moreover, on this FC2 install, these are not
symbolic links. If they're multiply linked, the links are hard. They do
not show up in /etc/alternatives, nor in anything in /var/lib/alternatives.

Why are jar and rmic in there at all? Are they being used by the system,
and if I remove them will something break? How do I find out what else
to remove?

I really would prefer not to put the directory where I've installed
sun's java at the top of my path, but it looks like I have to put it
there if I want to compile sun-standard java 5 rmi.

--
Joel Rees   
digitcom, inc.   株式会社デジコム
Kobe, Japan   [phone]
** http://www.ddcom.co.jp **

[Matthew Zimmerman]

Joel wrote:
> (Apologies for the cross-post.)
>
> I asked
> > > What are jar, rmiregistry, and who knows what else doing in /usr/bin ?
> > >
> > > I know that everyone just shoves /usr/local/java/sdk/bin (or whatever)
> > > in at the top of $PATH, but I can think of several very good reasons
> > > that is not a good idea. So if there's a good reason, I'd like some
> > > feedback before I post a bug on this.
>
> Rahul explained
> > they are java related packages. they might have been installed by
> > default. if you dont want remove them. this is not a bug
>
> and James added
> > They're symlinks into the Red Hat alternatives scheme.
> > man 8 alternatives says:
> >   [...]
> >
> > So they allow you to have a number of Java virtual machines, and easily
> > swap from one to another.
>
> and then Matthew clarified
> > The Jpackage-style Java installs (including the gcj one included in FC3)
> > use the alternatives(8) system to manage simultaneous installation of 
> > multiple versions.
>
> Okay, I'll dig into the alternatives man page, although I really didn't
> want to know about that. Don't plan on using it.
>
> But I did not install any java at all when I installed Fedora. There was
> no javac in the same place. Moreover, on this FC2 install, these are not
> symbolic links. If they're multiply linked, the links are hard. They do
> not show up in /etc/alternatives, nor in anything in /var/lib/alternatives.
>
> Why are jar and rmic in there at all? Are they being used by the system,
> and if I remove them will something break? How do I find out what else
> to remove?

rpm is your friend! You can use it to figure out what package they're in:

matt@tomis ~ $ rpm -q -f /usr/bin/jar
libgcj-3.3.3-7

and then test removing it to see what other packages depend on it:

matt@tomis /etc/alternatives $ /bin/su
Password:
root@tomis /etc/alternatives $ rpm -e --test libgcj
error: Failed dependencies:
         libgcj.so.4 is needed by (installed) gettext-0.14.1-2.1
         libgcj = 3.3.3 is needed by (installed) libgcj-devel-3.3.3-7
         libgcj >= 3.3.3 is needed by (installed) gcc-java-3.3.3-7

In this case, if I didn't want GNU's java compiler, I could remove 
gcc-java and libgcj-devel, but there might be some other programs that 
use gettext:

root@tomis /etc/alternatives $ rpm -e --test gettext
error: Failed dependencies:
         gettext is needed by (installed) mutt-1.4.1-6

You'll need to remove the --test option to actually remove the packages, 
if you want to do that.

root@tomis /etc/alternatives $ man rpm