Makefile ifeq and Shell-Bash

Introduction

Makefile is a build automation tool that is commonly used in software development projects to compile and build code. It allows developers to define rules and dependencies for building and executing programs. The ifeq directive in Makefile is used to conditionally execute a block of code based on a specific condition. On the other hand, Shell-Bash is a scripting language commonly used in command-line environments to automate tasks and execute commands.

Makefile ifeq Directive

The ifeq directive in Makefile allows you to test whether a specific condition is true and execute a block of code accordingly. The general syntax for ifeq is as follows:

ifeq (<condition>, <value>)
    <code to execute if condition is true>
endif

Here's an example to demonstrate the usage of ifeq in Makefile:

ifeq ($(OS),Windows)
    $(info Running on Windows)
else
    $(info Running on $(shell uname -s))
endif

In this example, the ifeq directive checks if the value of the OS variable is equal to "Windows". If it is true, it will print "Running on Windows". Otherwise, it will print "Running on " using the Shell-Bash command uname -s to get the current operating system.

Shell-Bash in Makefile

Makefile allows you to use Shell-Bash commands and scripts to perform various tasks during the build process. You can use the $(shell ...) function to execute shell commands and capture their output. Here's an example to illustrate the usage of Shell-Bash in Makefile:

SOURCES := $(wildcard *.c)
OBJECTS := $(SOURCES:.c=.o)

all: $(OBJECTS)

%.o: %.c
    gcc -c $< -o $@
    
clean:
    rm -f $(OBJECTS)

In this example, the $(wildcard ...) function is used to capture a list of all C source files in the current directory. The $(OBJECTS) variable is then created by replacing the file extension from .c to .o. The $(OBJECTS) target is built by compiling each corresponding source file using the gcc command, and the clean target can be used to remove the generated object files.

Conclusion

Makefile ifeq directive and Shell-Bash commands provide powerful capabilities for conditionally executing code and performing tasks in build automation scripts. By utilizing these features, programmers can efficiently manage and automate the build process of their software projects.