Using Autotools in the LTP Build Process

The Linux Test Project (LTP) uses the GNU Autotools build system to configure and compile the source code. The key components of Autotools are autoconf, autoreconf, and ./configure. Below is an explanation of their purpose and a typical workflow for building LTP.

Purpose of Autotools Commands

autoconf - Generates the configure script from configure.ac (or configure.in). - The configure.ac file contains macros that test for system features, libraries, and headers required for the build.
autoreconf - A wrapper script that runs all the necessary Autotools commands (e.g., autoconf, automake, aclocal, etc.) in the correct order. - Useful when the build system needs to be regenerated from scratch.
./configure - A shell script generated by autoconf that checks the system for dependencies, libraries, and headers. - Generates Makefile and other configuration files based on the system environment.

Typical Workflow for Building LTP

Below is a regular session or workflow for building LTP using Autotools:

Clone the LTP Repository - Start by cloning the LTP repository from GitHub.
```
git clone https://github.com/linux-test-project/ltp.git
cd ltp
```
Generate the Build System - If the configure script is not present or needs to be regenerated, use autoreconf.
```
autoreconf -fvi
```
- This command ensures that all necessary Autotools scripts are up-to-date.
Run the Configure Script - Execute the ./configure script to check for system dependencies and generate the Makefile.
```
./configure
```
- You can specify additional options, such as installation prefix:
```
./configure --prefix=/opt/ltp
```
Compile the Source Code - Use make to compile the source code.
```
make
```
Install the Compiled Binaries - Install the compiled binaries to the specified prefix (e.g., /opt/ltp).
```
make install
```
Run LTP Tests - After installation, you can run the LTP tests from the installation directory.
```
/opt/ltp/runltp
```

Example Session

Here’s an example session for building LTP:

# Clone the LTP repository
git clone https://github.com/linux-test-project/ltp.git
cd ltp

# Regenerate the build system
autoreconf -fvi

# Configure the build
./configure --prefix=/opt/ltp

# Compile the source code
make

# Install the binaries
make install

# Run LTP tests
/opt/ltp/runltp

Summary

autoconf generates the configure script from configure.ac.
autoreconf regenerates the entire build system.
./configure checks for system dependencies and generates Makefile.
The typical workflow involves cloning the repository, regenerating the build system, configuring, compiling, and installing the software.