emgrip(1)
NAME
emgrip - converts a .deb to Emdebian Grip on-the-fly
Synopsis
- DEB_BUILD_OPTIONS='usegrip' emgrip [-v|--verbose] [-q|--quiet] [-o|--outdir DIRECTORY] FILENAME
- where FILENAME is a .dsc, a .changes or a .deb
emgrip -?|-h|--help|--version
Description
Converts a .deb package to Emdebian Grip by unpacking, pruning
particular classes of files (determined by DEB_BUILD_OPTIONS) and
repacking with a shortened description and the em1 version suffix.
When creating a public Emdebian Grip repository, it is strongly
recommended to specify .changes or .dsc files to allow the generation
of Emdebian TDebs from the source package as well as including the
source package itself in the repository.
If a file exists with the same name in the output directory, it will be
overwritten.
Copyright and Licence
Copyright (C) 1997-2000 Roman Hodek <roman@hodek.net>
Copyright (C) 2000-2002 Colin Watson <cjwatson@debian.org>
Copyright (C) 2002-2004 David Schleef <ds@schleef.org>
Copyright (C) 2004 Nikita Youshchenko <yoush@cs.msu.su>
Copyright (C) 2004 Raphael Bossek <bossekr@debian.org>
Copyright (C) 2007-2008 Neil Williams <codehelp@debian.org>
Copyright (C) 2005 Joey Hess <joeyh@debian.org>
This package is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
Emdebian Grip
- The idea here is based on dpkg-cross:
- 1. receive .deb or .changes as a command-line option
2. parse DEB_BUILD_OPTIONS
3. unpack the .deb as dpkg-cross does
4. remove files as per DEB_BUILD_OPTIONS
5. repack the .deb with an Emdebian version suffix.
6. build new .deb and revise .changes so that the
original source can be retained. - 7. Include the gripped packages into a local mirror
to reduce the size of Packages.gz and the size of
the mirror itself. - As few dependencies as possible - this script should become a new
package and have a new set of lintian checks to allow perl etc.
NO FUNCTIONAL CHANGES IN THE FINAL .DEB !- Conversion of Debian TDebs to Emdebian TDebs needs to be done inside
the source package so a .changes file is needed for this step. If the
.changes file references a Debian TDeb, emgrip will run 'em_installtdeb -a $arch --no-sign' inside the source package (where $arch is
determined from the contents of the .changes file). - Individual packages containing translation files will have the
translation files removed and Debian TDebs are skipped. - Future versions will also have to understand Dpkg Classes but until
those are implemented, this uses brute force. - The new package also needs dh_grip which can be added to all
debian/rules files just before dpkg-build .. or dh_builddeb and which
does nothing in the normal circumstance but does the same as emgrip
*if* the DEB_BUILD_OPTIONS "usegrip" is set or if the other
DEB_BUILD_OPTIONS are set, like "nodocs", "nohelp" or "noessential". - Alternatively, set the build options by placing a file in
/etc/dpkg/origins/ containing the build options in a field called "Grip-Build-Option" and call "emgrip" with the "--vendor" option or
"DEB_VENDOR" environment variable. - dpkg-vendor fields used by emgrip with default values:
Vendor: emdebian-grip
Vendor-Name: Emdebian Grip
Grip-Build-Option: usegrip
Short-Desc-Suffix: gripped- The "Short-Desc-Suffix" is wrapped in parentheses and appended to the
short description [default is 'gripped'].
DEB_BUILD_OPTIONS
- If none of these options are set, emgrip does nothing.
- nodocs
- Remove all content in /usr/share/doc/*/ except the copyright
file and compress the copyright file itself. Remove manpages
and info pages (translated or not). Also remove doc-base files
that describe the documentation that no longer exists.
nohelp- Remove even help files from all packages, including -doc packages.
Includes removing /usr/share/gtk-doc/html and
/usr/share/gnome/help/\$package
Despite removing the help files, dependencies on help file utilities
like scrollkeeper will remain, at least for Lenny.
noessential- Remove the 'Essential: yes' tag from DEBIAN/control - this
is a brute force removal, no additional dependencies are to
be generated (no patches) so care is needed here.
nolintian- Remove all files from /usr/share/lintian/overrides and
/usr/share/linda/overrides - saves up to 1Mb.
usegrip- Combination flag that sets all DEB_BUILD_OPTIONS for Emdebian
Grip - noessential, nohelp, nodocs, nolintian
nosymbols- Currently being tested - the idea is to drop DEBIAN/symbols files
but this could have unpredictable effects on packages built on a
system lacking these symbols. The space saved by dropping these files
might not be worth the cost, so 'usegrip' does not yet activate
'nosymbols'. This might be suitable for Crush, maybe not Grip.
noperl- Remove any file that is found to be a perl script text executable
by 'file' - used by Crush.
usecrush- Combination flag that adds nosymbols and noperl to usegrip.
Field removal
- Functional control fields are retained but the question arises:
- Who defines functional?
- Well, for the current purposes of Emdebian Grip, functional includes
only the following control fields:
Package
Source
Version
Architecture
Maintainer
Installed-Size
Depends
Pre-Depends
Conflicts
Replaces
Section
Priority
Description
Task- Recommends is explicitly rejected, as is Suggests - the expectation is
that Emdebian Grip will disable Install-Recommends in apt anyway, so
that Gripped packages can be mixed with Debian or locally-built
packages. - Note also that 'Essential' is not.
- Homepage, VCS* and all X- control fields are dropped.
- The net result is a (potentially) much cleaner dpkg database.
- The description is trimmed to four lines (or three if the fourth line
is empty).
Automation
- Relatively simple, but a few checks are needed in case your list of
possible packages includes packages already processed by dpkg-cross. - #!/bin/sh
set -e - DIR=/tmp/myrepo/
for deb in `ls /var/cache/apt/archives/*.deb`; do
cross=`echo $deb | grep "\-.*-cross" || true`
if [ ! -z "$cross" ]; then
echo "skipping dpkg-cross package: $deb"
continue - fi
DEB_BUILD_OPTIONS="nodocs nohelp usegrip" ./emgrip -o $DIR $deb - done
- With "dpkg-vendor" support, DEB_BUILD_OPTIONS can be replaced by
setting the vendor. - A similar script should be able to cope with obtaining .changes files
to retain the source packages. - Despite using dcut internally, emgrip isn't set up to obtain the
.changes files directly from http://incoming.debian.org, a wrapper
script would be needed. - An additional wrapper is likely to be needed to allow an Emdebian Grip
repository to "catch-up" with the existing Debian mirrors, e.g. if the
first upload to the Grip repository is a binary-only upload without a
referenced .orig.tar.gz. - emgrip does ensure that the .tar.gz is copied into the output directory
and reprepro can locate the relevant files if the --ignore=missingfile
option is passed. Sadly, this functionality is not preserved in the
reprepro processincoming mode. - To ease the process of gripping an existing mirror, the emdebian-grip
package depends on 'reprepro' to create a filtered Debian mirror that
can be kept up to date, generates meta-data for Emdebian Grip, builds
gripped packages in an 'incoming/' directory and includes the packages into the final Emdebian Grip repository. - Once a package has been "gripped", the binary packages could be removed
from the filtered mirror - the source packages (particularly the
.orig.tar.gz) are probably best retained in the filtered mirror.
Pruning empty directories
A subroutine to prune directories has been tested in emgrip and it is
possible to identify directories that were intentionally empty in the
Debian package. However, aggressively removing directories that end up
as empty after removal of unsupported scripts and files is likely to be
a step too far. Some packages may expect a directory to exist merely
because a file was originally packaged into that directory, so we need
Dpkg Classes to tell the difference.
- emgrip therefore leaves empty directories in place.