Script to move a file preserving Git history, rewriting history in the process

bin/gitmv

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+#!/bin/bash
+#
+# git-mv-with-history -- move/rename file or folder, with history.
+#
+# Moving a file in git doesn't track history, so the purpose of this
+# utility is best explained from the kernel wiki:
+#
+#   Git has a rename command git mv, but that is just for convenience.
+#   The effect is indistinguishable from removing the file and adding another
+#   with different name and the same content.
+#
+# https://git.wiki.kernel.org/index.php/GitFaq#Why_does_Git_not_.22track.22_renames.3F
+#
+# While the above sucks, git has the ability to let you rewrite history
+# of anything via `filter-branch`. This utility just wraps that functionality,
+# but also allows you to easily specify more than one rename/move at a
+# time (since the `filter-branch` can be slow on big repos).
+#
+# Usage:
+#
+#   git-rewrite-history [-d/--dry-run] [-v/--verbose] <srcname>=<destname> <...> <...>
+#
+# After the repsitory is re-written, eyeball it, commit and push up.
+#
+# Given this example repository structure:
+#
+#   src/makefile
+#   src/test.cpp
+#   src/test.h
+#   src/help.txt
+#   README.txt
+#
+# The command:
+#
+#   git-rewrite-history README.txt=README.md  \     <-- rename to markdpown
+#                       src/help.txt=docs/    \     <-- move help.txt into docs
+#                       src/makefile=src/Makefile   <-- capitalize makefile
+#
+#  Would restructure and retain history, resulting in the new structure:
+#
+#    docs/help.txt
+#    src/Makefile
+#    src/test.cpp
+#    src/test.h
+#    README.md
+#
+# @author emiller
+# @date   2013-09-29
+# @url    https://gist.github.com/tupy/79ec62fee769d4049db2
+#
+
+function usage() {
+  echo "usage: `basename $0` [-d/--dry-run] [-v/--verbose] <srcname>=<destname> <...> <...>"
+  [ -z "$1" ] || echo $1
+
+  exit 1
+}
+
+[ ! -d .git ] && usage "error: must be ran from within the root of the repository"
+
+dryrun=0
+filter=""
+verbose=""
+repo=$(basename `git rev-parse --show-toplevel`)
+
+while [[ $1 =~ ^\- ]]; do
+  case $1 in
+    -d|--dry-run)
+      dryrun=1
+      ;;
+
+    -v|--verbose)
+      verbose="-v"
+      ;;
+
+    *)
+      usage "invalid argument: $1"
+  esac
+
+  shift
+done
+
+for arg in $@; do
+  val=`echo $arg | grep -q '=' && echo 1 || echo 0`
+  src=`echo $arg | sed 's/\(.*\)=\(.*\)/\1/'`
+  dst=`echo $arg | sed 's/\(.*\)=\(.*\)/\2/'`
+  dir=`echo $dst | grep -q '/$' && echo $dst || dirname $dst`
+
+  [ "$val" -ne 1  ] && usage
+  [ ! -e "$src"   ] && usage "error: $src does not exist"
+
+  filter="$filter                            \n\
+    if [ -e \"$src\" ]; then                 \n\
+      echo                                   \n\
+      if [ ! -e \"$dir\" ]; then             \n\
+        mkdir -p ${verbose} \"$dir\" && echo \n\
+      fi                                     \n\
+      mv $verbose \"$src\" \"$dst\"          \n\
+    fi                                       \n\
+  "
+done
+
+[ -z "$filter" ] && usage
+
+if [[ $dryrun -eq 1 || ! -z $verbose ]]; then
+  echo
+  echo "tree-filter to execute against $repo:"
+  echo -e "$filter"
+fi
+
+[ $dryrun -eq 0 ] && git filter-branch -f --tree-filter "`echo -e $filter`"