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## Introducing arch

up: arch Meets hello-world next: System Requirements

`arch` is a revision control, source code management, and configuration management tool.

This manual is an `arch` tutorial: its purpose is to help you get started using `arch` for the first time, and then learn some of the more advanced features of arch.

### Who is this Manual For?

In order to use this manual, you should be familiar with the basic unix command line tools (such as `ls` , `mv` , and `find` ).

In addition, you should be familiar with the programs `diff` and `patch` and the concept of a `patchset` .

It is very helpful, but not strictly necessary if you have used or are at least familiar with other revision control systems such as `CVS` .

### Where's the Reference Manual?

`arch` is largely a self documenting program. The command:

            % tla help

will provide you with a categorized list of all available commands, and for a given command `foo` ,

            % tla foo -H

will provide you with documentation for that command.

### Another Source of Help -- the Mailing List

Arch is sufficiently different from older and competing systems that new users are often a bit disoriented for the first few days. You may find it helpful to seek help on the `gnu-arch-users` mailing list which you can find via links from:

        http://www.gnu.org/software/gnu-arch

### What is Revision Control?

A "revision control system" is a librarian and coordination tool for trees of files and the changes made to them. For example, a typical software project uses revision control to keep track of how the project's source code evolves over time, to keep track of each change to that code (such as each bug fix or feature addition), to share those changes among all the programmers working on the project and help them remain in sync, and to combine changes made at different times and/or by different programmers into a single source tree.

A "source management tool" is one that helps you to manage large source trees even if they have many more files that you can keep track of "by hand". For example, a source management tool can inventory the source files in a tree, distinguish the source files from scratch files and and other files that maybe stored there, and inform you when source files are added and deleted.

"Configuration Management" addresses the needs of projects which combine multiple, separately maintained source trees into a single tree. A configuration management tool helps you to easily construct the combined project and to keep track of how development on the component parts is synchronized.

### Why Use arch?

`arch` has a number of advantages compared to competing systems. Among these are:

Works on Whole Trees `arch` keeps track of whole trees -- not just individual files. For example, if you change many files in a tree, `arch` can record all of those changes as a group rather than file-by-file; if you rename files or reorganize a tree, `arch` can record those tree arrangements along with your changes to file contents.

Changeset Oriented `arch` doesn't simply "snapshot" your project trees. Instead, `arch` associates each revision with a particular changeset: a description of exactly what has changed. `arch` provides changeset oriented commands to help you review changesets, merge trees by applying changesets, examine the history of a tree by asking what changesets have been applied to it, and so forth.

Fully Distributed `arch` doesn't rely on a central repository . For example, there is no need to give write access to a project's archive to all significant contributors, instead, each contributor can have their own archive for their work. `arch` seamlessly operates across archive boundaries.

arch Meets hello-world: A Tutorial Introduction to The arch Revision Control System
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