Ruby

Install the interpreter:

# aptitude install ruby

If the package is already present, you can mark it as manually installed:

# aptitude unmarkauto ruby

# aptitude install build-essential dh-make fakeroot lintian

# aptitude install libmail-box-perl

# aptitude install devscripts

# aptitude install cdbs

# aptitude install gem2deb

# set variables for Debian packaging
export DEBFULLNAME="Full Name (GPG key comment)"
export DEBEMAIL="address@example.org"

$ gpg --list-key "$DEBFULLNAME <$DEBEMAIL>"

Setting up chroots for building Debian packages

In order to build Debian packages in a clean room environment, it is recommended to do so inside a proper chroot. The following package helps creating and maintaining chroot environments:

# aptitude install pbuilder

Prepare directories for chroot environments and for configuration files, inside your regular user's home directory:

$ mkdir -p ~/var/cache/pbuilder/result/sid \
  ~/var/cache/pbuilder/aptcache/sid ~/.pbuilder

Create the following configuration file:

$ cat ~/.pbuilder/sid.conf
export HOME=/home/username
DISTRIBUTION="sid"
COMPONENTS="main"
MIRRORSITE="http://http.debian.net/debian"
APTCACHE="${HOME}/var/cache/pbuilder/aptcache/${DISTRIBUTION}/"
APTCACHEHARDLINK="no"
AUTOCLEANAPTCACHE="yes"
BASETGZ="${HOME}/var/cache/pbuilder/${DISTRIBUTION}-base.tgz"
BUILDPLACE="${HOME}/var/cache/pbuilder/build/"
BUILDRESULT="${HOME}/var/cache/pbuilder/result/${DISTRIBUTION}/"
HOOKDIR=""
DEBBUILDOPTS="-i -I"
BINDMOUNTS=""
USE_PDEBUILD_INTERNAL="yes"
DEBOOTSTRAPOPTS[0]="--variant=buildd"
DEBOOTSTRAP="debootstrap"
EXTRAPACKAGES="gnupg debian-archive-keyring"
USEPROC="yes"
USEDEVPTS="yes"
USEDEVFS="no"
REMOVEPACKAGES="lilo elilo grub-legacy grub-pc"
BUILDSOURCEROOTCMD="fakeroot"
PBUILDERROOTCMD="sudo"
BUILDUSERID="9999"
BUILDUSERNAME="pbuilder"
export DEBIAN_FRONTEND="noninteractive"
AUTO_DEBSIGN="yes"
PKGNAME_LOGFILE="yes"
PKGNAME_LOGFILE_EXTENTION=".buildlog"
export debian_chroot="pbuild$$"

where username should be substituted by your actual username. Create and populate a hook directory for pbuilder build:

$ mkdir -p ~/.pbuilder/build-hooks-sid
$ EXDIR=/usr/share/doc/pbuilder/examples
$ ln -s $EXDIR/B90lintian $EXDIR/B91dpkg-i $EXDIR/B92test-pkg \
  $EXDIR/C10shell ~/.pbuilder/build-hooks-sid

Then, create a hook directory for pdebuild:

$ mkdir -p ~/.pbuilder/pdeb-hooks-sid

and populate it with the following hook scripts:

$ cd ~/.pbuilder/pdeb-hooks-sid
$ WEBDIR=http://www.inventati.org/frx/progs/scripts
$ wget $WEBDIR/D05prepare_pdeb $WEBDIR/prepare_pdeb.conf \
  $WEBDIR/B10lintian_pdeb $WEBDIR/B20testinst_pdeb \
  $WEBDIR/B50shell_pdeb
$ chmod u+x [DB]*pdeb
$ ln -s B50shell_pdeb C50shell_pdeb

Now, create file /etc/sudoers.d/50pbuilder in order to give your regular user limited root privileges necessary to run pbuilder:

# cat /etc/sudoers.d/50pbuilder
User_Alias PBUILDER_USERS = listofusers
Cmnd_Alias PBUILDER_CMNDS = /usr/sbin/pbuilder
PBUILDER_USERS ALL = PBUILDER_CMNDS

where listofusers should be substituted with a comma-separated list of usernames which will be allowed to run pbuilder with root privileges. Then make sure the file has the right permissions:

# chmod 0440 /etc/sudoers.d/50pbuilder

Now, create the Debian unstable chroot environment:

$ sudo pbuilder create --configfile ~/.pbuilder/sid.conf

Before building packages, remember to update the chroot environment:

$ sudo pbuilder update --configfile ~/.pbuilder/sid.conf

In order to build a package you may use pbuilder build on an already created Debian source package:

$ sudo pbuilder build --configfile ~/.pbuilder/sid.conf \
  --hookdir ~/.pbuilder/build-hooks-sid  package_x.y.z-w.dsc

Alternatively, you may use pdebuild inside the package directory. For instance, if you start from an already created Debian source package, you can do the following:

$ dpkg-source -x package_x.y.z-w.dsc
$ cd package_x.y.z/
$ pdebuild --configfile ~/.pbuilder/sid.conf \
  -- --hookdir ~/.pbuilder/pdeb-hooks-sid

Obviously you may make any modification you like to the package before invoking pdebuild. Please note that the latter command will attempt to sign the package with the GPG key of the last modifier; if you do not have the modifier's secret key (e.g. because you are not the person specified in the Debian changelog), you can sign the package with another secret key:

$ pdebuild --configfile ~/.pbuilder/sid.conf --debsign-k $MYID \
  -- --hookdir ~/.pbuilder/pdeb-hooks-sid

where $MYID should be substituted with your name, e-mail address, comment, or key identifier.

If you need some packages from Debian experimental in order to build the package, you may enable an additional repository for that branch:

$ pdebuild --configfile ~/.pbuilder/sid.conf \
  -- --hookdir ~/.pbuilder/pdeb-hooks-sid \
  --othermirror 'deb http://http.debian.net/debian experimental main' \
  --override-config

Remember to add a line starting with 'UPDATE' to the ~/.pbuilder/pdeb-hooks-sid/prepare_pdeb.conf configuration file, in order for the above to work correctly.

If you need to use your chroot environment in a quick throw-away manner (for debugging purposes or the like), you may log in to it with the following command:

$ sudo pbuilder login --configfile ~/.pbuilder/sid.conf