install-dotfiles

#!/bin/sh
# -*- ksh -*-

set -euf

# files containing this string in the first 3 lines will
# be left alone.
save="install-dotfiles-preserve"

# on my shiny new Mac, /bin/sh doesn't honor the -n flag
# this is why we can't have nice things
echon () {
  /bin/echo -n "$@"
}

if [ -z "$HOME" ]; then
  echo "\$HOME not set.  I can't guess where you hid the git repository."
  exit 1
fi

cvsdir=''
for dir in "$HOME"/git/dotfiles "$(pwd)" ; do
  if [ -z "$cvsdir" ] && [ -d "$dir" ]; then
    cvsdir="$dir"
    echo "repository dotfiles directory is $cvsdir"
  fi
done

if [ -z "$cvsdir" ]; then
  echo "Unable to deduce the repository."
  exit 0
fi

cd "${HOME}"
# /bin/ls -1 | egrep -v '^(README.md|CVS|install-dotfiles)$' | sed 's/$/ \\/'
for dotfile in \
Xresources \
bash_profile \
bashrc \
gdbinit \
gitconfig \
git-global-ignore \
guile \
inputrc \
screenrc \
tcshrc \
tmux.conf \
zprofile \
zshrc \
               ; do
  echon "${dotfile}: "

  # 0.  Check for override; ignore if so
  if test -e ."$dotfile" ; then
      if head -3 ."$dotfile" | grep -q "$save" ; then
          echo "exists, and is marked to keep; skip."
          continue
      fi
  fi

  # 1.  blow away old links
  # -L is a link on bash; -h is on FreeBSD /bin/sh?
  # -h seems to work on bash
  if [ -h ".${dotfile}" ]; then
    echon "removing old link, "
    rm ".${dotfile}"
  fi

  # 2.  move aside old file
  if [ -e ".${dotfile}" ]; then
    echon "moving file to ${dotfile}.old, "
    mv ".$dotfile" "${dotfile}.old"
  fi

  # 3.  install new link
  echon "installing link, "
  ln -s "$cvsdir/$dotfile" ".$dotfile"

  if test "#!" = "$(head -1 "$cvsdir/$dotfile" | cut -c1-2)"  ; then
    echon "making executable, "
    chmod +x "$cvsdir/$dotfile"
  fi

  echo "done."
done

for f in \
    emacs \
    ; do
    echon "$f: "
    if [ -f ".$f" ]; then
        echon "found unwanted file, moving to $f.old, "
        mv ".$f" "${f}".old
        echo done.
    else
        echo "no old file found."
    fi
done