4.2.7. Some Questions and Answers

• Q. I thought this was going to be a discussion about modems??!

  A. Ah. You must be thinking of the serial ports on the back of your computer. We're using `port' here to mean the result of `porting' a program from one version of Unix to another. (It's an unfortunate bad habit of computer people to use the same word to refer to several completely different things).

• Q. I thought you were supposed to use packages to install extra programs?

  A. Yes, that's usually the quickest and easiest way of doing it.

• Q. So why bother with ports then?

  A. Several reasons:-

  1. The licensing conditions on some software distributions require that they be distributed as source code, not binaries.

  2. Some people don't trust binary distributions. At least with source code you can (in theory) read through it and look for potential problems yourself.

  3. If you've got some local patches, you'll need the source to add them yourself.

  4. You might have opinions on how a program should be compiled that differ from the person who did the package - some people have strong views on what optimisation setting should be used, whether to build debug versions and then strip them or not, etc. etc.

  5. Some people like having code around, so they can read it if they get bored, hack around with it, borrow from it (licence terms permitting, of course!) and so on.

  6. If you ain't got the source, it ain't software! ;-)

• Q. What's a patch?

  A. A patch is a small (usually) file that specifies how to go from one version of a file to another. It contains text that says, in effect, things like ``delete line 23'', ``add these two lines after line 468'' or ``change line 197 to this''. Also known as a `diff', since it's generated by a program of that name.

• Q. What's all this about tarballs?

  A. It's a file ending in .tar.gz (with variations like .tar.Z, or even .tgz if you're trying to squeeze the names into a DOS filesystem).

  Basically, it's a directory tree that's been archived into a single file (.tar) and then compressed (.gz). This technique was originally used for Tape ARchives (hence the name `tar'), but it's a widely used way of distributing program source code around the Internet.

  You can see what files are in them, or even extract them yourself, by using the standard Unix tar program, which comes with the base FreeBSD system, like this:-

   tar tvzf foobar.tar.gz		# View contents of foobar.tar.gz
   tar xzvf foobar.tar.gz		# Extract contents into the current directory
  

• Q. And a checksum?

  A. It's a number generated by adding up all the data in the file you want to check. If any of the characters change, the checksum will no longer be equal to the total, so a simple comparison will allow you to spot the difference. (In practice, it's done in a more complicated way to spot problems like position-swapping, which won't show up with a simplistic addition).

• Q. I did what you said for compiling ports from a CDROM and it worked great until I tried to install the kermit port:-

   # make install
   >> cku190.tar.gz doesn't seem to exist on this system.
   >> Attempting to fetch from ftp://kermit.columbia.edu/kermit/archives/.
  

  Why can't it find it? Have I got a dud CDROM?

  A. The licensing terms for kermit don't allow us to put the tarball for it on the CDROM, so you'll have to fetch it by hand - sorry! The reason why you got all those error messages was because you weren't connected to the Internet at the time. Once you've downloaded it from any of the sites above, you can re-start the process (try and choose the nearest site to you, though, to save your time and the Internet's bandwidth).

• Q. I did that, but when I tried to put it into /usr/ports/distfiles I got some error about not having permission.

  A. The ports mechanism looks for the tarball in /usr/ports/distfiles, but you won't be able to copy anything there because it's sym-linked to the CDROM, which is read-only. You can tell it to look somewhere else by doing

   DISTDIR=/where/you/put/it make install
  

• Q. Does the ports scheme only work if you have everything in /usr/ports? My system administrator says I must put everything under /u/people/guests/wurzburger, but it doesn't seem to work.

  A. You can use the PORTSDIR and PREFIX variables to tell the ports mechanism to use different directories. For instance,

   PORTSDIR=/u/people/guests/wurzburger/ports make install
  

  will compile the port in /u/people/guests/wurzburger/ports and install everything under /usr/local.

   
   PREFIX=/u/people/guests/wurzburger/local make install
  

  will compile it in /usr/ports and install it in /u/people/guests/wurzburger/local.

  And of course

   PORTSDIR=.../ports PREFIX=.../local make install
  

  will combine the two (it's too long to fit on the page if I write it in full, but I'm sure you get the idea).

  If you don't fancy typing all that in every time you install a port (and to be honest, who would?), it's a good idea to put these variables into your environment.

• Q. I don't have a FreeBSD CDROM, but I'd like to have all the tarballs handy on my system so I don't have to wait for a download every time I install a port. Is there an easy way to get them all at once?

  A. To get every single tarball for the ports collection, do

   # cd /usr/ports
   # make fetch
  

  For all the tarballs for a single ports directory, do

   # cd /usr/ports/directory
   # make fetch
  

  and for just one port - well, I think you've guessed already.

• Q. I want to know what files make is going to need before it tries to pull them down.

  A. 'make fetch-list' will display a list of the files needed for a port.

• Q. Is there any way to stop the port from compiling? I want to do some hacking on the source before I install it, but it's a bit tiresome having to watch it and hit control-C every time.

  A. Doing 'make extract' will stop it after it has fetched and extracted the source code.

• Q. I'm trying to make my own port and I want to be able to stop it compiling until I've had a chance to see if my patches worked properly. Is there something like 'make extract', but for patches?

  A. Yep, 'make patch' is what you want. And by the way, thank you for your efforts!

• Q. I've heard that some compiler options can cause bugs. Is this true? How can I make sure that I compile ports with the right settings?

  A. Yes, with version 2.6.3 of gcc (the version shipped with FreeBSD 2.1.0 and 2.1.5), the -O2 option could result in buggy code unless you used the -fno-strength-reduce option as well. (Most of the ports don't use -O2). You should be able to specify the compiler options used by something like

   # CFLAGS='-O2 -fno-strength-reduce' make install
  

  or by editing /etc/make.conf, but this doesn't always seem to get picked up. The surest way is to do 'make configure', then go into the source directory and inspect the Makefiles by hand, but this can get tedious if the source has lots of sub-directories, each with their own Makefiles.

• Q. There's so many ports it's hard to find the one I want. Is there a list anywhere of what ports are available?

  A. Look in the INDEX file in /usr/ports.

• Q. I went to install the 'foo' port but the system suddenly stopped and starting compiling the 'bar' port. What's going on?

  A. The 'foo' port needs something that's supplied with 'bar' - for instance, if 'foo' uses graphics, 'bar' might have a library with useful graphics processing routines. Or 'bar' might be a tool that's needed to compile the 'foo' port.

• Q. I installed the grizzle program from the ports and frankly it's a complete waste of disk space. I want to delete it but I don't know where it put all the files. Any clues?

  A. No problem, just do

   pkg_delete grizzle-6.5
  

• Q. Hang on a minute, you have to know the version number to use that command. You don't seriously expect me to remember that, do you??

  A. Not at all, you can find it out by doing

   pkg_info -a | grep grizzle
  

  And it'll tell you:-

   Information for grizzle-6.5:
   grizzle-6.5 - the combined piano tutorial, LOGO interpreter and shoot 'em up arcade game.
  

• Q. Nope, that's still too complicated.

  A. Do 'pkg_manage' to get a friendly front-end to the package manager.

• Q. Talking of disk space, the ports directory seems to be taking up an awful lot of room. Is it safe to go in there and delete things?

  A. Yes, if you've installed the program and are fairly certain you won't need the source again, there's no point in keeping it hanging around. The best way to do this is

   # cd /usr/ports
   # make clean
  

  which will go through all the ports subdirectories and delete everything except the skeletons for each port.

• Q. I tried that and it still left all those tarballs or whatever you called them in the distfiles directory. Can I delete those as well?

  A. Yes, if you're sure you've finished with them, those can go as well.

• Q. I like having lots and lots of programs to play with. Is there any way of installing all the ports in one go?

  A. Just do

   # cd /usr/ports
   # make install
  

• Q. OK, I tried that, but I thought it would take a very long time so I went to bed and left it to get on with it. When I looked at the computer this morning, it had only done three and a half ports. Did something go wrong?

  A. No, the problem is that some of the ports need to ask you questions that we can't answer for you (eg ``Do you want to print on A4 or US letter sized paper?'') and they need to have someone on hand to answer them.

• Q. I really don't want to spend all day staring at the monitor. Any better ideas?

  A. OK, do this before you go to bed/work/the local park:-

   # cd /usr/ports
   # make -DBATCH install
  

  This will install every port that does not require user input. Then, when you come back, do

   # cd /usr/ports
   # make -DIS_INTERACTIVE install
  

  to finish the job.

• Q. At work, we're using frobble, which is in your ports collection, but we've altered it quite a bit to get it to do what we need. Is there any way of making our own packages, so we can distribute it more easily around our sites?

  A. No problem, assuming you know how to make patches for your changes:-

   # cd /usr/ports/somewhere/frobble
   # make extract
   # cd work/frobble-2.8
   [Apply your patches]
   # cd ../..
   # make package
  

• Q. This ports stuff is really clever. I'm desperate to find out how you did it. What's the secret?

  A. Nothing secret about it at all, just look at the bsd.ports.mk and bsd.ports.subdir.mk files in your makefiles directory. (Note: readers with an aversion to intricate shell-scripts are advised not to follow this link...)