Generating .gitignore Entries from Makefile

User:
What is the best way to specify that .gitignore ignore the binary executables generated in a project?
Assistant:
The best way is to analyze the Makefile to determine what binaries are being built. This ensures accuracy and avoids ignoring unrelated files.

Your shell-based heuristic using find and file is a good tool for discovery, but less ideal for persistent .gitignore entries.

Ideal approach:
  1. Use the Makefile to identify targets.
  2. Verify with your shell script to catch extras.
  3. Populate .gitignore accordingly.
User:
Write a script which reads Makefile and outputs a list of .gitignore lines to ignore binary executables.
Assistant:
Here is a Bash script that parses a Makefile for likely binary targets:
#!/bin/bash

# Script: makefile_gitignore_binaries.sh
# Purpose: Parse a Makefile to find executable build targets and suggest .gitignore lines.

MAKEFILE="Makefile"
[ -f "$MAKEFILE" ] || { echo "No Makefile found in current directory."; exit 1; }

echo "# Suggested .gitignore entries for binary targets in $MAKEFILE"
echo

# Grep for rules of the form:
# target: ...
# And filter out common non-binary targets like 'all', 'clean', etc.
grep -E '^[a-zA-Z0-9._/-]+:.*' "$MAKEFILE" | \
    grep -vE '^(all|clean|install|uninstall|check|test|docs|%.o):' | \
    cut -d: -f1 | while read -r target; do

    if [[ "$target" =~ ^[a-zA-Z0-9._/-]+$ ]]; then
        if [[ "$target" == */* ]]; then
            echo "$target"
        else
            echo "/$target"
        fi
    fi

done
Example: If your Makefile defines a target like:
mytool: main.o
	$(CC) -o mytool main.o
This script would output:
/mytool
which you can paste directly into your .gitignore file.