Makefile Target Bash Completion
Bash completion is a feature in the Bash shell that allows for automatic completion of commands, arguments, and file names. This can save time and reduce errors when entering commands, especially when working with complex Makefiles. In this article, we will explore how to use Makefile targets to enable Bash completion.
First, let's start by creating a simple Makefile. Open your favorite text editor and create a new file called "Makefile". In this file, we will define a few simple targets:
```
build:
@echo "Building project..."
test:
@echo "Running tests..."
clean:
@echo "Cleaning up..."
```
Save the file and exit the text editor. Now, let's try using Bash completion with our Makefile. Open a terminal and navigate to the directory where you saved the Makefile. Type "make" and press the "Tab" key twice. You should see a list of available targets: build, test, and clean.
This is the basic functionality of Bash completion. However, we can do better by defining specific completion rules for each target. This will allow for more precise and efficient completion.
To do this, we will use the ".bash_completion" file. This file contains the completion rules for various commands and programs. If you don't already have this file, you can create it in your home directory. Open your text editor and create a new file called ".bash_completion".
In this file, we will define the completion rules for our Makefile targets. The syntax for defining these rules is:
```
complete -W "list of options" command
```
In our case, the command is "make" and the list of options is the targets in our Makefile. So, our completion rules will look like this:
```
complete -W "build test clean" make
```
Save the file and exit the text editor. Now, we need to tell Bash to use this ".bash_completion" file. Open your ".bashrc" file and add the following line at the end:
```
. ~/.bash_completion
```
Save the file and exit the text editor. Now, open a new terminal or source your ".bashrc" file. Navigate to the directory where you saved the Makefile and type "make" followed by the "Tab" key twice. You should see the same list of targets as before. However, this time, try typing the first letter of a target and then pressing the "Tab" key. You should see Bash completing the target for you.
For example, type "m" and press "Tab". Bash will complete it to "make". Then, type "b" and press "Tab". Bash will complete it to "make build". This allows for more efficient and accurate completion of targets.
Now, let's take this a step further and add arguments to our targets. Modify your Makefile to include the following targets:
```
build:
@echo "Building project..."
test:
@echo "Running tests..."
clean:
@echo "Cleaning up..."
install:
@echo "Installing project..."
```
Save the file and exit the text editor. Next, we need to modify our ".bash_completion" file to include arguments for our targets. The syntax for this is:
```
complete -F _command command
```
In this case, the "_command" is the function that will define the completion rules for the specific command. So, our completion rules will look like this:
```
complete -F _make make
```
Next, we need to define the "_make" function in our ".bash_completion" file. Add the following lines to the file:
```
_make()
{
local cur prev opts
COMPREPLY=()
cur="${COMP_WORDS[COMP_CWORD]}"
prev="${COMP_WORDS[COMP_CWORD-1]}"
opts="build test clean install"
case "${prev}" in
build)
COMPREPLY=( $(compgen -W "-f -o" -- ${cur}) )
return 0
;;
test)
COMPREPLY=( $(compgen -W "-v -r" -- ${cur}) )
return 0
;;
install)
COMPREPLY=( $(compgen -W "-d -v" -- ${cur}) )
return 0
;;
*)
COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
return 0
;;
esac
}
```
This function defines the completion rules for each target and its respective arguments. The "compgen" command generates a list of possible completions based on the given options. Save the file and exit the text editor. Then, open a new terminal or source your ".bashrc" file.
