A simple, no-nonsense website blocker for macOS — with lockable focus sessions you can't quit early.

focus blocks sites at the OS level by editing /etc/hosts, so they're blocked in every browser at once. There's no extension to disable, no app to force-quit. When you start a locked session, a root background daemon re-applies the block every few seconds and survives reboots — so hand-editing your hosts file (or deleting the tool) won't get you back on Instagram until the timer runs out.

It comes in two flavors that share the same state:

• focus — a small, dependency-free Bash CLI.
• focus-tui — a full-screen terminal UI (Python + Textual) with a live toggle list.

Both read the same roster (~/.focus-sites) and edit the same managed block in /etc/hosts, so you can mix and match freely.

Browser extensions are trivial to disable the moment you feel the itch. focus is different:

• Every browser, at once. Blocking happens at the DNS/hosts layer, below the browser.
• Commitment mode. focus lock 90m starts a session with no early unlock. A root-owned daemon re-applies the block every 5 seconds, reverts manual edits automatically, and survives reboots. You can extend a lock, never shorten it.
• Clean. Everything lives inside a clearly-marked block in /etc/hosts; the rest of your file is never touched.

git clone https://github.com/ponchodelosrios98/screen-block.git
cd screen-block
chmod +x focus focus-tui

Optionally put them on your PATH:

sudo cp focus /usr/local/bin/focus

• macOS (uses /etc/hosts + mDNSResponder).
• focus — Bash only, no dependencies.
• focus-tui — uv (the script declares its own deps and runs itself). Or run it with any Python ≥ 3.10 that has textual>=0.80 installed.

Editing /etc/hosts requires sudo; you'll be prompted for your password.

./focus block instagram.com twitter.com   # block one or more sites
./focus unblock instagram.com             # unblock specific sites
./focus on                                # re-block everything on your list
./focus off                               # unblock everything (break time)
./focus list                              # show what's currently blocked
./focus lock 90m                          # LOCK your list for a set time
./focus status                            # show lock state + time left

Your block list lives in ~/.focus-sites, so on/off remember it between sessions.

./focus lock 90m       # lock for 90 minutes — no early unlock
./focus lock 2h        # or 2 hours
./focus lock 1h30m     # combined
./focus lock 45        # a bare number means minutes

While a lock is active:

• off and unblock are refused.
• You can block more sites (they get folded into the enforced set), but never remove them.
• focus lock <longer> extends the session; a shorter or equal duration is rejected.
• When the timer expires, the daemon unblocks everything and removes itself.

Durations accept s, m, h, d (e.g. 90m, 2h, 1h30m), or a bare number for minutes.

./focus-tui

A live table of your sites, each individually ● blocked or ○ allowed. Toggling flips it in /etc/hosts immediately.

The TUI authenticates sudo once up front (a normal password prompt before the UI opens), then reuses the cached credential.

• The block. Both tools rewrite a single region of /etc/hosts delimited by:

  # >>> focus block >>>
  127.0.0.1 instagram.com
  127.0.0.1 www.instagram.com
  # <<< focus block <<<
  

  Anything outside those markers is left untouched. After each change, the DNS cache is flushed (dscacheutil -flushcache + killall -HUP mDNSResponder).

• The lock. focus lock installs a root LaunchDaemon (com.focus.enforcer) plus a small enforcer script and a lock file under /Library/Application Support/focus/. The daemon loops every 5 seconds: while the lock file's expiry epoch is in the future it re-applies the block; once it expires it unblocks everything, removes the daemon, plist and lock file, and exits. KeepAlive + RunAtLoad mean it comes back after a reboot.

Because the enforcer, plist and lock file are root-owned, the tool can't casually clear them — that's the whole point.

Nothing is installed globally unless you copied focus to /usr/local/bin or ran a lock. To remove a stuck locked session (only possible with sudo, by design), wait for the timer — or, if you truly must:

sudo launchctl bootout system/com.focus.enforcer
sudo rm -f /Library/LaunchDaemons/com.focus.enforcer.plist \
           /usr/local/libexec/focus-enforcer
sudo rm -rf "/Library/Application Support/focus"

Then remove the managed block from /etc/hosts (everything between the two focus block markers).

MIT — do whatever you want. Contributions welcome.