README.md

/etc/hosts.mk

This Makefile automates the merging of the local /etc/hosts file with a remote /etc/hosts file obtained from a router at 192.168.15.1. The merged file ensures that duplicate entries are removed before updating the local /etc/hosts.

Features

• Fetches the /etc/hosts file from a remote router.
• Merges it with the local /etc/hosts file, removing duplicate entries.
• Ensures the merged file is valid before updating /etc/hosts.
• Prevents updates if the merged file is unexpectedly empty or too small.

Prerequisites

• ssh access to the router at 192.168.15.1 as root.
• GNU make installed.
• The local user must have the necessary permissions to modify /etc/hosts.

Installation

Place hosts.mk in /etc/hosts.mk:

sudo mv hosts.mk /etc/hosts.mk

Usage

Run make to execute the default target, which merges and displays the merged hosts file:

make -f /etc/hosts.mk

Fetch and View Remote Hosts

To fetch and display the remote hosts file:

make -f /etc/hosts.mk cat-hosts

Merge Hosts and View

To view the merged hosts file:

make -f /etc/hosts.mk cat-merged-hosts

Update /etc/hosts

To apply the merged hosts file:

sudo make -f /etc/hosts.mk /etc/hosts

Makefile Structure

.PHONY: cat-hosts cat-merged-hosts

cat-merged-hosts: /tmp/merged-hosts
	cat $<

cat-hosts:
	ssh [email protected] cat /etc/hosts

/tmp/remote-hosts:
	ssh [email protected] cat /etc/hosts >$@
	@test -s $@ || (echo "Error: $@ is empty. Aborting." && rm -f $@ && exit 1)

/tmp/merged-hosts: /tmp/remote-hosts
	@test -s $< || (echo "Error: $< is empty. Aborting." && rm -f $< && exit 1)
	cat /etc/hosts $^ | awk '!seen[$$0]++' > $@
	@test -s $@ || (echo "Error: $@ is empty. Aborting." && rm -f $@ && exit 1)

/etc/hosts: /tmp/merged-hosts
	@test -s $< || (echo "Error: $< is empty. Aborting." && rm -f $< && exit 1)
	@filesize=$$(stat -c%s $<) && \
	if [ $$filesize -ge 100 ]; then \
		cp $< $@ && echo "Updated /etc/hosts"; \
	else \
		echo "Skipping update: $< is smaller than 100 bytes"; \
	fi

License

This project is licensed under the MIT License.

etc-hosts.mk

.PHONY: cat-hosts cat-merged-hosts

cat-merged-hosts: /tmp/merged-hosts
	cat $<

cat-hosts:
	ssh [email protected] cat /etc/hosts

/tmp/remote-hosts:
	ssh [email protected] cat /etc/hosts >$@
	@test -s $@ || (echo "Error: $@ is empty. Aborting." && rm -f $@ && exit 1)

/tmp/merged-hosts: /tmp/remote-hosts
	@test -s $< || (echo "Error: $< is empty. Aborting." && rm -f $< && exit 1)
	cat /etc/hosts $^ | awk '!seen[$$0]++' > $@
	@test -s $@ || (echo "Error: $@ is empty. Aborting." && rm -f $@ && exit 1)

/etc/hosts: /tmp/merged-hosts
	@test -s $< || (echo "Error: $< is empty. Aborting." && rm -f $< && exit 1)
	@filesize=$$(stat -c%s $<) && \
	if [ $$filesize -ge 100 ]; then \
		cp $< $@ && echo "Updated /etc/hosts"; \
	else \
		echo "Skipping update: $< is smaller than 100 bytes"; \
	fi