It is rather rare that you will need to use the epoch, so before
you do that, think about it.
This version is usually what the source tarball uses as its
version. It is also called the upstream version.
The source version can include digits ([0-9]), letters ([a-zA-Z])
and periods (.). If the source package uses any other character,
it will need to be transformed to fit this scheme.
It is suggested that you should not use a source_version composed
exclusively of zeroes (i.e. 0, 0.0, 0.0.0, etc.)
The revision is an integer ([0-9]+) preceded by a minus (-). The
default is 1 (i.e. you do not need to put -1 at the end of a version).
The revision is used as the revision number of the package. It is
assumed to start at 1 and goes up incrementally each time you
change the control information of the package (i.e. each time
you change something in the control file other than the version
of the package.)
It is useful each time you find a bug in your package and create
a new package from the same source tarball. It usually is reset
each time you change the source version (some people prefer to
keep increasing the revision number since that represents the
version of their package.)
You cannot simply test two strings for equality since the version
strings "1.2.0" and "1.2" are not equal if directly compared with
strcmp() but will be found as equal with the version comparison.
There are two types of parts: major and minor.
The system compares minor parts one by one within one major part
before to move on to the next major part.
The major parts one those separated the colon (:), period (.) and
minus (-) characters.
Note, however, that the epoch and revision parts of two versions
are always compared together. Thus, if the
is missing some entries in one of the input versions,
empty strings for letters and zeroes (0) for numerical comparisons
are appended except for the revision. When a revision is missing
one (1) is used instead of zero (0).
2:5.3.2a-5 compared with 5.3
2:5.3.2a-5 compared with 0:5.3.0-1
empty string compared against "a"
Each major part is composed of one or more minor parts. One minor
part is either a string of letters ([a-zA-Z]+) or a decimal number
composed exclusively of digits ([0-9]+).
In the following figure, the third major part is ab57pre. It
is composed of three minor parts: ab, 57 and
Fig 1. how a version string is cut in pieces
The strings of letters in minor parts are compared
lexically not taking the case in account (i.e. 'a' equals 'A'.) When
one version has a string minor part and not the other, the other is assumed
to have an empty string minor part (""). A string minor part has priority
over an integer minor part.
1.a3 > 1.4 because "a" > ""
1.3a < 1.4 because 3 < 4
1.abc < 1.b because "abc" < "b"
The decimal numbers in minor parts are compared
numerically. Leading zeroes are ignored. When the minor part of one of
the versions is empty or undefined, it is considered to be the decimal
1.2 > 1.0.5 because 2 > 0
3.5.0 = 3.5 since the 3rd part in 3.5 is considered to be 0
2.5a < 2.5a1 because 0 < 1
4.2a34 < 4.2a100 because 34 < 100
To compare the full version A 2:3p.g.2q3-5
against the version B 2:3p.g.2q4 we generate the following
||A < B(1)
(1) comparison stops here
(2) defaults to 1 when not included
When it is necessary to compare a
version such as 1.2 with 1.2.3, it is assumed that 1.2
represents 1.2.0 and thus is older. For this reason, it
is important to keep the epoch and revision numbers
clearly separate from the source version. The following
table shows the comparison between the version A
3:184.108.40.206-2 and version B 3:2.5-2.
||A > B
As we can see, the comparison stops as soon
as one of the numbers does not match. The result of the whole comparison
is the result of that specific pair of numbers. Note that the two
missing sub-versions in 3:2.5-2 are replaced by 0.
Debian also support the character plus (+) in their versions.
That character would need to be considered as larger than 'z'
and 'Z'. At this time, there does not seem much of a need
to include that character in a version, however. Thus
wpkg will not accept a plus in a version.
Each package has a version. This version is
saved in the Version
field of the control file.
This is the version used to know whether you
are upgrading or downgrading a package you are trying to install.
It is also the version used to compare between modules to know whether
you have a compatible version of a required package.
The Depends field is not checked in version 0.1 of wpkg.
Most packages will have a list of sub-packages they
depend on. For instance, the DLL version of the z library depends on the
base mingw package which includes the MinGW DLL library. And the
international version of bison depends on gettext to print out messages
is a list of package names optionaly followed by a minimum, maximum, equal
or range of versions for that package. When such a version is specified,
it is compared against the
field of the named package.
Depends: sswf (>= 1.6.1)
means the following test must be true
installed_packages["sswf"].version >= 1.6.1
The Build-Depends field is not checked in version 0.1 of wpkg.
Like Depends, you have a
field which lists packages with their versions. This part is used whenever
you want to build the package to make sure that you have all the necessary
tools to build the package successfully.
The .deb files have a version embedded in
them. That version is currently 2.0 (which is also what dpkg currently
supports.) This version is written on one line including one new-line
character (\n only, no \r!). That one line is saved in a file named
debian-binary file is
added first in the .deb package.
It is assumed that all versions of wpkg which
support a version 2, will be capable of supporting all the versions
2.x (2.0, 2.1, 2.2, etc.)
To check the version of a .deb file, use the
The version is displayed as the Debian package version.
Because this is mainly for the different wpkg tools to check for
compatibility, there is no great interface to extract this version
(and it should not be necessary anyway.)
Of course, wpkg, the tool, also has a version
of its own. You can query the wpkg version with the
The wpkg version is composed of two decimal
numbers separated by a period as in 0.1.
It is likely that the wpkg packages will also
be as simple since in most cases the maintainer of wpkg will make sure
the package is working as expected. Yet, once in a while, you may see
a revision number on the package name (as in: