New feature : boolean variables and expressions
megastep at megastep.org
Wed Mar 29 19:20:49 EST 2006
I have just committed a big patch I have been working on for the past
couple of days. This new features allows the creation of user-defined
boolean variables from within installer files, which can be
referenced with a simple evaluation language to create complex
Basically this allows for very fine-grained control over what files
get installed. My main motivation for this at first was to have an
easy way to automatically install GTK 1.x or 2.x binaries. This
system is advanced enough to make the previous "arch", glibc, etc.
I'll just post here the relevant entry from README.xml :
The BOOL element :
This element allows the user to create some complex expressions to
installer. This element allows the user to define boolean conditions,
the values of
which are defined by arbritrary scripts. These booleans can then be
used as part
of expressions used by other elements, like FILE or BINARY below, to
This element must be a direct child of the root INSTALL element.
Booleans are global
to a particular instance of the installer. Additionally, the
installer itself defines
a set of standard booleans, as described below.
Booleans are intended to replace the previous filtering mechanisms,
using "arch", "libc"
and so on attributes, while providing additional flexibility.
Booleans are case sensitive.
The BOOL element takes one mandatory attribute :
name The symbolic name for the boolean (variable name). May
be up to 30 characters
long, and must start with an alphanumerical character.
May not contain blank
Additionally, one of the following attributes must be used :
script The command to be run to determine the value of the
boolean. In the UNIX
tradition, it should return 0 for a TRUE value.
envvar The name of an environment variable to query for the
value of the boolean.
The value must be a non-zero number to map to be TRUE.
If the variable is not
set in the environment, the boolean will likewise be set
It also recognizes two optional attributes :
later If set to "yes", the script will be executed at the time
that the condition
referencing it is evaluated. The default is to run the
script once immediately
upon initialization to gather the static value.
if Additionally make this boolean dependent on another
boolean expression. This
expression can reference any previously defined boolean.
See below for more details
about the syntax. If this expression evaluates to FALSE,
then the script won't be
run, or the environment queried, and the value will also
be set to FALSE.
Standard booleans defined by the installer :
- Standard 'true' and 'false' booleans.
- 'is-root' is TRUE if the installer is running as root.
- 'reinstalling' is TRUE if the product is already installed.
- 'bzip2' is TRUE if Bzip2 decompression is available in the installer.
- One boolean corresponding to the selected user interface: gtk1,
gtk2, carbon, dialog, console
- One boolean for the CPU architecture: x86, ppc, sparc, alpha, etc
- One boolean for the detected libc version: libc5, glibc-2.1, etc.
- One boolean for the distribution / OS name : redhat, suse, aix,
- A boolean for the OS name as returned by uname.
- Two booleans representing the detection distribution version (not
always meaningful) :
distro-major-<number> and distro-minor-<number>.
= Booleans for the detected locale setting and its encoding, e.g.
en_US, ISO-8859-1, etc.
- On Linux, 'selinux' indicates whether SELinux is available and
- If RPM support was compiled in, 'rpm-support' is set. If RPM 3.x,
then 'rpm3-support' is
also set to TRUE.
For example, on a Redhat Linux 7.3 sytem, the following bools would
be defined to TRUE :
Linux, x86, redhat, distro-major-7, distro-minor-3
About Boolean Expressions :
Many elements support the 'if' or 'condition' attribute to reference
using the Setup boolean variables. The expressions have to follow the
expression := [!]<operator>(<expression1>,<expression2>) |
Supported operators are : + (logical "and"), | (logical "or"), and ^
(logical "exclusive or").
Any expression can be negated by a ! prefix.
An undefined boolean is the same as a false boolean.
Some examples :
Match Fedora on PowerPC system:
Match one of SuSE, Redhat 9 or Fedora, on all but Intel:
megastep at megastep.org
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