install-app

A handy utility for installing and upgrading software, whether compiling from source or using a package manager.

Introduction

This script removes much of the drudgery associated with installing and upgrading software. It supports retrieving distribution files as well as configuring / compiling / installing arbitrary software applications. Unlike package managers such as Red Hat's rpm, Debian's dpkg, Sun's pkgadd, etc., install-app works typically with a application's source, giving you complete flexibility in terms of configuration and installation. Indeed, the flexibility is such that you can even use it with your OS' package manager. [Another difference vis-a-vis install-app and package managers is that install-app does not itself support dependencies among applications or application removals.]

install-app requires Perl 5 along with the following Perl modules:

• Carp
• File::Find
• Getopt::Long
• LWP::Debug
• LWP::UserAgent
• Text::Wrap
• XML::Twig

If your system does not have these modules installed already, visit CPAN for help. Note that LWP::Debug, LWP::UserAgent, and XML::Twig are not included with the default Perl distribution so you may need to install them yourself. Also note that XML::Twig itself requires the Expat XML parser library.

Application Info Files

For each application you wish to support with this script, you must have a special file -- an application info file -- containing information about the application: where the distribution file is located, how to verify its integrity, how to compile the application, etc. An application info file resides in the directory specified in the script by $apps_dir.

An application info file is an XML document. Currently, the document must only be well-formed, although at some point I hope to create a document type definition (DTD) with which it can be validated. In the meantime, here is a table listing the elements that can appear in an application info file along with the meaning of each:

XPath	Meaning
name	Alternate name of the application. This can be useful encoded in other elements such as distfile when you want to give the application info file a friendlier name; eg, spamassassin instead of Mail::SpamAssassin.
url	Homepage for the application. [NB: unused by install-app.
install/basedir	Base directory where distribution file is saved and files are extracted. install-app will create it if it doesn't already exist.
install/workdir	Work directory, created either implicitly when extracting files or explicitly as part of a postextract action. install-app will change into this after extracting files and perform each step there. If a relative path, it will be relative to the base directory.
install/distfile	Distribution filename for a specific version.
install/durl	URL from which the distribution file can be obtained. install-app supports file retrievals via HTTP and FTP using LWP.
install/verify	Method used to verify contents of the distribution file. Possible methods are md5 (MD5 checksum), sha1 (SHA1 checksum), sha256 (SHA256 checksum), and sig (GnuPG / PGP signature). If omitted, install-app will not attempt to verify the integrity of the distribution file.
install/vurl	URL used to obtain the MD5/SHA1/SHA256 checksum or GnuPG / PGP signature for the distribution file.
install/preextract	Command(s) run before extracting contents of the distribution file. These are passed to the shell for execution. Note: if they exit with a non-zero return code, install-app will regard that as a failure and abort.
install/postextract	Command(s) run after extracting contents of the distribution file but before changing ownership of the working directory or performing any steps. These are passed to the shell for execution. Note: if they exit with a non-zero return code, install-app will regard that as a failure and abort.
install/step/label	Descriptive label of the action to be performed for a given step.
install/step/action	Command(s) to be performed for a given step. These are passed to the shell for execution. Generally, there will be multiple steps for an application; they will be performed in the order they appear in the application info file. Note: if an action exits with a non-zero return code, install-app will regard it as a failure and abort.
install/component	Can hold any / all of the same elements as install, except for component. Intended for applications that consist of multiple distribution files.

Within an element, text can be encoded using one or more special strings:

Encoding	Replaced By
%a	Name of the application as specified on the commandline.
%b	The text of the basedir element.
%f	The text of the distfile element.
%n	The text of the name element.
%v	The version number specified on the commandline.
%w	The text of the workdir element.

Installation

• Retrieve the script and save it locally.
• Verify ownership and permissions on the script and configuration file - they should be owned by root.
• Create an application info file for each application you wish to have install-app support. Some examples are: iptables.xml and [perl.xml](perl.xml. Note: these are intended as guides to help you write your own application info files. While you may choose to use them as-is to install these particular applications, you may prefer to use different steps or even not install the applications at all.
• Verify ownership and permissions on the script as well as application info files.
• Edit the script and set $ENV{PATH}, $apps_dir, and $proxy according to your environment. Also, you may wish to adjust the location of the perl interpreter in the first line as well as other variable initializations to suit your tastes.
• Optionally, retrieve the stylesheet app.xsl for use in displaying application info files.

Use

You specify applications to install / upgrade on the commandline as one or more name / version number pairs. For each application, install-app will read the corresponding application info file and then use the information it obtains to retrieve the appropriate distribution file, verify its integrity, extract it, and configure / compile / install the application. At each step, you will be prompted to continue to the next step or skip it.

There are several commandline arguments you can use; some override variables defined in the script itself:

Option	Meaning
-a, --list-apps	List the applications supported on this system and exit.
-b, --batch	Don't ask questions. NB: you may still be prompted by the programs you are actually running.
-d, --debug	Display debugging messages while running. NB: installs still occur.
-l, --list-steps	List the steps to make and install the application but don't actually do them.

Examples:

Invocation	Meaning
install-app openssl 0.9.7a	retrieves / builds / installs OpenSSL 0.9.7a.
install-app -b openssl 0.9.7a	same as above but do it in batch.
install-app -l openssl 0.9.7a	lists steps involved in building / installing OpenSSL 0.9.7a.
install-app --list-apps	lists supported applications.

Known Bugs and Caveats

Currently, I am not aware of any bugs in this script.

The application info files contain arbitrary commands that are run as root. Be careful about what you put in them, and be careful about their ownership / permissions.

Make sure you set $ENV{'FTP_PASSIVE'} in the script if your firewall requires passive mode for FTP file transfers.

You may sometimes be prompted for information while running install-app, even when using its batch option (eg, -b). By carefully choosing the steps followed in an application info file, you can minimize or even eliminate the need for user interaction. For instance, don't have a step that invokes vi to edit a makefile; instead, use sed to edit a it in place. Also, note that install-app sets the environment variable INSTALL_APP_MODE to batch if running in batch mode so you have a step that, say, allows you to page through a changelog only if running interactively.

Currently, install-app requires that distribution files be tar files compressed using compress, gzip, or bzip.

If you encounter a problem using install-app, I encourage you to enable debug mode (eg, add -d to your commandline) and examine the output it produces before contacting me. Often, this will enable you to resolve the problem yourself.

Copyright and License

Copyright (c) 2003-2022, George A. Theall. All rights reserved.

This script is free software; you can redistribute it and/or modify it under the same terms as Perl itself.