How to tell autoconf to run specific commands in with 'make install'

Autoconf is a powerful tool used in the software development process to configure and install software on different systems. It provides a way to generate a portable and customizable script called a configure script, which is responsible for detecting the system's capabilities and dependencies.

When we run the make install command after compiling the software, autoconf executes a series of predefined commands to install the software on the system. However, sometimes we may need to specify additional commands to be executed during the installation process. In this article, we will learn how to tell autoconf to run specific commands with make install.

Understanding the Autoconf Workflow

Before we dive into how to customize the make install command, let's understand the basic workflow of Autoconf:

1. Run the ./configure command: This command generates the configure script based on the configure.ac file, which contains the project's configuration information.
2. Configure script execution: The configure script is executed to determine the system's capabilities and dependencies. It checks for the presence of required libraries, compilers, and other tools.
3. Compilation: Once the configure script successfully completes, we can run the make command to compile the software.
4. Installation: Finally, we run the make install command to install the compiled software on the system.

Telling Autoconf to Run Specific Commands

Autoconf provides a way to define custom installation commands through the install-exec-hook and install-data-hook macros. These macros allow us to specify commands that should be executed during the installation process.

The install-exec-hook macro is used to define commands that should be executed when installing executable files, while the install-data-hook macro is used for non-executable files, such as documentation or configuration files.

To add custom commands to the installation process, follow these steps:

1. Edit the configure.ac file: Open the configure.ac file in a text editor.
2. Locate the AC_OUTPUT macro: Look for the AC_OUTPUT macro in the configure.ac file. This macro is responsible for generating the Makefile.
3. Add the install-exec-hook and install-data-hook macros: Just before the AC_OUTPUT macro, add the following lines:

Replace path/to/executable with the actual path to the executable file you want to modify permissions for. You can add multiple commands by separating them with semicolons (;).

Save the configure.ac file and exit the text editor.

Now, when you run the make install command, Autoconf will execute the specified commands in the install-exec-hook and install-data-hook macros.

Example: Adding a Custom Command

Let's say we want to add a custom command to change the permissions of an executable file called "myapp". Here's how we can do it:

1. Edit the configure.ac file: Open the configure.ac file in a text editor.
2. Locate the AC_OUTPUT macro: Look for the AC_OUTPUT macro in the configure.ac file.
3. Add the install-exec-hook macro: Just before the AC_OUTPUT macro, add the following line:

Save the configure.ac file and exit the text editor.

Now, when you run the make install command, Autoconf will execute the chmod +x myapp command to make the "myapp" file executable during the installation process.

Conclusion

In this article, we have learned how to tell Autoconf to run specific commands with the make install command. By using the install-exec-hook and install-data-hook macros in the configure.ac file, we can customize the installation process according to our needs.

Autoconf provides a flexible way to configure and install software on different systems, making it easier for developers to distribute their software to a wide range of users. By understanding and utilizing the capabilities of Autoconf, we can ensure a smooth installation process for our software.

References

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