fix(init): use process substitution instead of pipe for bootstrap

Change the canonical invocation from `curl ... | zsh` to
`zsh <(curl ...)`.  With process substitution, stdin remains the
terminal, so sudo prompts and other interactive input work without
any /dev/tty workarounds or credential caching tricks.

Reject piped stdin with a helpful error message (except in CI, which
has no TTY but also has no interactive prompts).

Author: ebkn

README.md

@@ -6,12 +6,12 @@ Personal dotfiles for macOS and Linux.
 
 ```sh
 # macOS
-curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh | zsh
+zsh <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh)
 ```
 
 ```sh
 # Ubuntu
-curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh | bash
+bash <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh)
 ```
 
 ## What's included

bin/init/bootstrap-macos.sh

@@ -1,21 +1,14 @@
 #!/bin/zsh
 set -eo pipefail
 # Bootstrap script for a fresh Mac.
-# Usage: curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh | zsh
+# Usage: zsh <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh)
 
-# When invoked via `curl ... | zsh`, stdin is the pipe.  sudo and other
-# interactive prompts need the real terminal, so we verify /dev/tty early
-# and cache sudo credentials before any commands that require them.
-if [ ! -e /dev/tty ]; then
-  printf "error: /dev/tty is not available; cannot run interactively\n" >&2
+if [ ! -t 0 ] && [ "${CI:-}" != "true" ]; then
+  printf "error: stdin must be a terminal. Run with:\n" >&2
+  printf "  zsh <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh)\n" >&2
   exit 1
 fi
 
-# Cache sudo credentials up front via /dev/tty (stdin is the curl pipe).
-# A background loop keeps them fresh so long-running steps don't re-prompt.
-sudo -S -v < /dev/tty
-while true; do sudo -n true; sleep 60; kill -0 "$$" || exit; done 2>/dev/null &
-
 DOTFILES_DIR="${HOME}/dotfiles"
 
 # Install Xcode Command Line Tools if missing.
@@ -40,4 +33,4 @@ if [ ! -d "$DOTFILES_DIR" ]; then
   git clone https://github.com/ebkn/dotfiles "$DOTFILES_DIR"
 fi
 
-exec zsh "${DOTFILES_DIR}/bin/init/macos.sh" </dev/tty
+exec "${DOTFILES_DIR}/bin/init/macos.sh"

bin/init/bootstrap-ubuntu.sh

@@ -1,21 +1,14 @@
 #!/bin/bash
 set -eo pipefail
 # Bootstrap script for a fresh Ubuntu machine.
-# Usage: curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh | bash
+# Usage: bash <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh)
 
-# When invoked via `curl ... | bash`, stdin is the pipe.  sudo and other
-# interactive prompts need the real terminal, so we verify /dev/tty early
-# and cache sudo credentials before any commands that require them.
-if [ ! -e /dev/tty ]; then
-  printf "error: /dev/tty is not available; cannot run interactively\n" >&2
+if [ ! -t 0 ] && [ "${CI:-}" != "true" ]; then
+  printf "error: stdin must be a terminal. Run with:\n" >&2
+  printf "  bash <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh)\n" >&2
   exit 1
 fi
 
-# Cache sudo credentials up front via /dev/tty (stdin is the curl pipe).
-# A background loop keeps them fresh so long-running steps don't re-prompt.
-sudo -S -v < /dev/tty
-while true; do sudo -n true; sleep 60; kill -0 "$$" || exit; done 2>/dev/null &
-
 DOTFILES_DIR="${HOME}/dotfiles"
 
 # Install git if missing.
@@ -31,4 +24,4 @@ if [ ! -d "$DOTFILES_DIR" ]; then
   git clone https://github.com/ebkn/dotfiles "$DOTFILES_DIR"
 fi
 
-exec bash "${DOTFILES_DIR}/bin/init/ubuntu.sh" </dev/tty
+exec "${DOTFILES_DIR}/bin/init/ubuntu.sh"

bin/init/macos.sh

@@ -2,7 +2,7 @@
 #
 # Setup script for macOS. Requires Xcode CLT and (on Apple Silicon) Rosetta.
 # On a fresh Mac, use the bootstrap script instead:
-#   curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh | zsh
+#   zsh <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-macos.sh)
 
 set -eo pipefail
 

bin/init/ubuntu.sh

@@ -2,7 +2,7 @@
 #
 # Setup script for Ubuntu. Requires git.
 # On a fresh machine, use the bootstrap script instead:
-#   curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh | bash
+#   bash <(curl -fsSL https://raw.githubusercontent.com/ebkn/dotfiles/main/bin/init/bootstrap-ubuntu.sh)
 #
 set -eo pipefail