How to use the command 'libtool' (with examples)

The command ’libtool’ is a generic library support script that simplifies the usage of shared libraries by providing a consistent and portable interface. It allows users to compile source files, create libraries or executables, install shared libraries, and perform various other functions related to library management.

Use case 1: Compile a source file into a libtool object

Code:

libtool --mode=compile gcc -c path/to/source.c -o path/to/source.lo

Motivation: When you have a source file that you want to compile into a libtool object, you can use this example to generate the object file. This object file can then be used to create a library or executable.

Explanation:

• --mode=compile: Specifies the mode of operation as compilation.
• gcc: The compiler to use for compilation, in this case, ‘gcc’.
• -c: Tells the compiler to compile the source file without linking.
• path/to/source.c: The path to the source file that needs to be compiled.
• -o path/to/source.lo: Specifies the output file name and location of the compiled object file.

Example output: The source file ‘source.c’ will be compiled into an object file named ‘source.lo’ in the specified location.

Use case 2: Create a library or an executable

Code:

libtool --mode=link gcc -o path/to/library.lo path/to/source.lo

Motivation: This example demonstrates how to create a library or an executable using libtool. By linking the object files generated from compilation, you can create a functional library or executable.

Explanation:

• --mode=link: Specifies the mode of operation as linking.
• gcc: The linker to use for linking, in this case, ‘gcc’.
• -o path/to/library.lo: Specifies the output file name and path for the library or executable.
• path/to/source.lo: The path to the object file generated from compilation, which will be linked to create the library or executable.

Example output: The object file ‘source.lo’ will be linked to create a library or executable named ’library.lo’ in the specified location.

Use case 3: Automatically set the library path for uninstalled libtool generated programs or libraries

Code:

libtool --mode=execute gdb path/to/program

Motivation: When you want to use a program or library generated by libtool without installing it, you can use this example to automatically set the library path. This allows the program to find and use the necessary dependencies.

Explanation:

• --mode=execute: Specifies the mode of operation as execution.
• gdb: The program to be executed, in this case, ‘gdb’ (GNU Debugger).
• path/to/program: The path to the program or library that needs to be executed.

Example output: The specified program ‘gdb’ will be executed, and the library path will be automatically set to ensure that the program can find the required dependencies.

Use case 4: Install a shared library

Code:

libtool --mode=install cp path/to/library.la path/to/installation_directory

Motivation: This example demonstrates how to install a shared library generated by libtool. Installing a library makes it accessible to other programs or users on the system.

Explanation:

• --mode=install: Specifies the mode of operation as installation.
• cp: The command to copy files.
• path/to/library.la: The path to the library file that needs to be installed.
• path/to/installation_directory: The directory where the library needs to be installed.

Example output: The library file ’library.la’ will be copied to the specified installation directory, making it available for other programs to link against.

Use case 5: Complete the installation of libtool libraries on the system

Code:

libtool --mode=finish path/to/installation_dir

Motivation: After installing libtool libraries on a system, using this example allows you to complete the installation process and set up any necessary final configurations or adjustments.

Explanation:

• --mode=finish: Specifies the mode of operation as finishing the installation.
• path/to/installation_dir: The directory where the libraries have been installed.

Example output: The installation process for the libtool libraries in the specified directory will be completed, which may include setting appropriate permissions, creating necessary symlinks, or performing other system-specific actions.

Use case 6: Delete installed libraries or executables

Code:

libtool --mode=uninstall path/to/installed_library.la

Motivation: If you want to remove an installed library or executable generated by libtool, you can use this example to uninstall it from the system.

Explanation:

• --mode=uninstall: Specifies the mode of operation as uninstallation.
• path/to/installed_library.la: The path to the installed library or executable that needs to be removed.

Example output: The specified library or executable file will be uninstalled from the system, removing it so that it is no longer accessible.

Use case 7: Delete uninstalled libraries or executables

Code:

libtool --mode=clean rm path/to/source.lo path/to/library.la

Motivation: When you have object files or library files generated by libtool that have not been installed, and you want to clean up and remove them, you can use this example.

Explanation:

• --mode=clean: Specifies the mode of operation as cleaning.
• rm: The command to remove files.
• path/to/source.lo: The path to the object file that needs to be removed.
• path/to/library.la: The path to the library file that needs to be removed.

Example output: The specified object file and library file will be deleted, removing them from the system.

Conclusion:

In this article, we have explored several use cases of the ’libtool’ command. From compiling source files and creating libraries or executables to installing and uninstalling libraries, libtool provides a convenient interface for managing shared libraries. By following the provided examples, you can leverage the power of libtool for your library management needs.