Frequently asked questions

Here, known problems and frequently asked questions are documented. This portion was initially available in README.Debian file, but moved here.

pbuilder create fails

It often happens that pbuilder cannot create the latest chroot. Try upgrading pbuilder and debootstrap. It is currently only possible to create software that handles the past. Future prediction is a feature which may be added later after we have become comfortable with the past.

There are people who occasionally back port debootstrap to stable versions; hunt for them.

When there are errors with the debootstrap phase, the debootstrap script needs to be fixed. pbuilder does not provide a way to work around debootstrap.

Directories that cannot be bind-mounted

Because of the way pbuilder works, there are several directories which cannot be bind-mounted when running pbuilder. The directories include /tmp, /var/cache/pbuilder, and system directories such as /etc and /usr. The recommendation is to use directories under the user’s home directory for bind-mounts.

Logging in to pbuilder to investigate build failure

It is possible to invoke a shell session after a build failure. Example hook scripts are provided as C10shell and C11screen scripts. C10shell script will start bash inside chroot, and C11screen script will start GNU screen inside the chroot.

Logging in to pbuilder to modify the environment

It is sometimes necessary to modify the chroot environment. login will remove the contents of the chroot after logout. It is possible to invoke a shell using hook scripts. pbuilder update executes ‘E’ scripts, and a sample for invoking a shell is provided as C10shell.

$ mkdir ~/loginhooks
$ cp C10shell ~/loginhooks/E10shell
$ sudo pbuilder update --hookdir ~/loginhooks/E10shell

It is also possible to add --save-after-exec and/or --save-after-login options to the pbuilder login session to accomplish the goal. It is possible to add the --uml-login-nocow option to pbuilder-user-mode-linux session as well.

Setting BUILDRESULTUID for sudo sessions

It is possible to set

BUILDRESULTUID=$SUDO_UID

in pbuilderrc to set the proper BUILDRESULTUID when using sudo.

Notes on usage of $TMPDIR

If you are setting $TMPDIR to an unusual value, of other than /tmp, you will find that some errors may occur inside the chroot, such as dpkg-source failing.

There are two options, you may install a hook to create that directory, or set

export TMPDIR=/tmp

in pbuilderrc. Take your pick.

An example script is provided as examples/D10tmp with pbuilder.

Creating a shortcut for running pbuilder with a specific distribution

When working with multiple chroots, it would be nice to work with scripts that reduce the amount of typing. An example script pbuilder-distribution.sh is provided as an example. Invoking the script as pbuilder-squeeze will invoke pbuilder with a squeeze chroot.

Using environmental variables for running pbuilder for specific distribution

This section [1] describes briefly a way to setup and use multiple pbuilder setups by creating a pbuilderrc configuration in your home path ($HOME/.pbuilderrc) and using the variable “DIST” when running pbuilder or pdebuild.

[1]

This part of the documentation contributed by Andres Mejia

This example was taken from a wiki (https://wiki.ubuntu.com/PbuilderHowto).

First, setup $HOME/.pbuilderrc to look like:

if [ -n "${DIST}" ]; then
        BASETGZ="`dirname $BASETGZ`/$DIST-base.tgz"
        DISTRIBUTION="$DIST"
        BUILDRESULT="/var/cache/pbuilder/$DIST/result/"
        APTCACHE="/var/cache/pbuilder/$DIST/aptcache/"
fi

Then, whenever you wish to use pbuilder for a particular distro, assign a value to “DIST” that is one of the distros available for Debian or any Debian based distro you happen to be running (i.e. whatever is found under /usr/lib/debootstrap/scripts).

Here’s some examples on running pbuilder or pdebuild:

DIST=gutsy sudo pbuilder create

DIST=sid sudo pbuilder create --mirror http://http.us.debian.org/debian

DIST=gutsy sudo pbuilder create \
        --othermirror "deb http://archive.ubuntu.com/ubuntu gutsy universe \
        multiverse"

DIST=gutsy sudo pbuilder update

DIST=sid sudo pbuilder update --override-config --mirror \
http://http.us.debian.org/debian \
--othermirror "deb http://http.us.debian.org/debian sid contrib non-free"

DIST=gutsy pdebuild

Using special apt sources lists, and local packages

If you have some very specialized requirements on your apt setup inside pbuilder, it is possible to specify that through the --othermirror option. Try something like: --othermirror "deb http://local/mirror stable main|deb-src http://local/source/repository ./"

To use the local file system instead of HTTP, it is necessary to do bind-mounting. --bindmounts is a command-line option useful for such cases.

It might be convenient to use your built packages from inside the chroot. It is possible to automate the task with the following configuration. First, set up pbuilderrc to bindmount your build results directory.

BINDMOUNTS="/var/cache/pbuilder/result"

Then, add the following hook

# cat /var/cache/pbuilder/hooks/D70results
#!/bin/sh
cd /var/cache/pbuilder/result/
/usr/bin/dpkg-scanpackages . /dev/null > /var/cache/pbuilder/result/Packages
/usr/bin/apt-get update

This way, you can use deb file:/var/cache/pbuilder/result

To add new apt-key inside chroot:

sudo pbuilder --login --save-after-login
# apt-key add - <<EOF
...public key goes here...
EOF
# logout

How to get pbuilder to run apt-get update before trying to satisfy build-dependency

You can use hook scripts for this. D scripts are run before satisfying build-dependency.

This snippet comes from Ondrej Sury.

Different bash prompts inside pbuilder login

To make distinguishing bash prompts inside pbuilder easier, it is possible to set environment variables such as PS1 inside pbuilderrc

With versions of bash more recent than 2.05b-2-15, the value of the debian_chroot variable, if set, is included in the value of PS1 (the Bash prompt) inside the chroot. In prior versions of bash, [2] setting PS1 in pbuilderrc worked.

[2]Versions of bash from and before Debian 3.0

example of debian_chroot

export debian_chroot="pbuild$$"

example of PS1

export PS1="pbuild chroot 32165 # "

Creating a chroot reminder

Bash prompts will help you remember that you are inside a chroot. There are other cases where you may want other signs of being inside a chroot. Check out the examples/F90chrootmemo hook script. It will create a file called /CHROOT inside your chroot.

Using /var/cache/apt/archives for the package cache

For the help of low-bandwidth systems, it is possible to use /var/cache/apt/archives as the package cache. Just specify it instead of the default /var/cache/pbuilder/aptcache.

It is however not possible to do so currently with the user-mode-linux version of pbuilder, because /var/cache/apt/archives is usually only writable by root.

Use of dedicated tools such as apt-proxy is recommended, since caching of packages would benefit the system outside the scope of pbuilder.

pbuilder back ported to stable Debian releases

Currently stable back port of pbuilder is available at backports.org.

Warning about LOGNAME not being defined

You might see a lot of warning messages when running pbuilder.

dpkg-genchanges: warning: no utmp entry available and LOGNAME not defined; using uid of process (1234)

It is currently safe to ignore this warning message. Please report back if you find any problem with having LOGNAME unset. Setting LOGNAME caused a few problems when invoking chroot. For example, dpkg requires getpwnam to succeed inside chroot, which means LOGNAME and the related user information have to be set up inside chroot.

Cannot Build-conflict against an essential package

pbuilder does not currently allow Build-Conflicts against essential packages. It should be obvious that essential packages should not be removed from a working Debian system, and a source package should not try to force removal of such packages on people building the package.

Using fakechroot

It is possible to use fakechroot instead of being root to run pbuilder; however, several things make this impractical. fakechroot overrides library loads and tries to override default libc functions when providing the functionality of virtual chroot. However, some binaries do no use libc to function, or override the overriding provided by fakechroot. One example is ldd. Inside fakechroot, ldd will check the library dependency outside of the chroot, which is not the expected behavior.

To work around the problem, debootstrap has a --variant fakechroot option. Use that, so that ldd and ldconfig are overridden.

Make sure you have set your LD_PRELOAD path correctly, as described in the fakechroot manpage.

Using debconf inside pbuilder sessions

To use debconf inside pbuilder, setting DEBIAN_FRONTEND to “readline” in pbuilderrc should work. Setting it to “dialog” should also work, but make sure whiptail or dialog is installed inside the chroot.

nodev mount options hinder pbuilder activity

If you see messages such as this when building a chroot, you are mounting the file system with the nodev option.

/var/lib/dpkg/info/base-files.postinst: /dev/null: Permission denied

You will also have problems if you mount the file system with the noexec option, or nosuid. Make sure you do not have these flags set when mounting the file system for /var/cache/pbuilder or $BUILDPLACE.

This is not a problem when using user-mode-linux.

See 316135 for example.

pbuilder is slow

pbuilder is often slow. The slowest part of pbuilder is extracting the tar.gz every time pbuilder is invoked. That can be avoided by using pbuilder-user-mode-linux. pbuilder-user-mode-linux uses COW file system, and thus does not need to clean up and recreate the root file system.

pbuilder-user-mode-linux is slower in executing the actual build system, due to the usual user-mode-linux overhead for system calls. It is more friendly to the hard drive.

pbuilder with cowdancer is also an alternative that improves speed of pbuilder startup.

Using pdebuild to sponsor package

To sign a package marking for sponsorship, it is possible to use --auto-debsign and --debsign-k options of pdebuild.

pdebuild --auto-debsign --debsign-k XXXXXXXX

Why is there a source.changes file in ../?

When running pdebuild, pbuilder will run dpkg-buildpackage to create a Debian source package to pass it on to pbuilder. File named XXXX_YYY_source.changes is what remains from that process. It is harmless unless you try to upload it to the Debian archive.

This behavior is different when running through --use-pdebuild-internal

amd64 and i386-mode

amd64 architectures are capable of running binaries in i386 mode. It is possible to use pbuilder to run packages, using linux32 and debootstrap –arch option. Specifically, a command-line option like the following will work.

pbuilder create --distribution sid --debootstrapopts --arch --debootstrapopts i386 \
         --basetgz /var/cache/pbuilder/base-i386.tgz --mirror http://ftp.jp.debian.org/debian
linux32 pbuilder build --basetgz /var/cache/pbuilder/base-i386.tgz

Using tmpfs for buildplace

To improve speed of operation, it is possible to use tmpfs for pbuilder build location. Mount tmpfs to /var/cache/pbuilder/build, and set

APTCACHEHARDLINK=no

Using svn-buildpackage together with pbuilder

pdebuild command can be used with svn-buildpackage –svn-builder command-line option. [3]

[3]Zack has posted an example on his blog.
alias svn-cowbuilder="svn-buildpackage --svn-builder='pdebuild --pbuilder cowbuilder"