This script is sample Subversion to Git migration scripts to perform references relocation, bad commit message fix, lost merge history restore etc.

svn_to_git_post_migration.sh

#!/bin/bash
# This script should be launched under the top level git directory.

function clean_up() {
    rm -fr .git/svn
    rm -fr .git/info/grafts
    git branch -d trunk
    git gc
}

function uplift_refs() {
    for entry in $(git for-each-ref --format="%(objectname)|%(refname)")
    do
        oldref=$(echo $entry | cut -d '|' -f 2)
        if [[ $oldref =~ remotes ]]
        then
            sha=$(echo $entry | cut -d '|' -f 1)
            if [[ $oldref =~ remotes/tags ]]
            then
                newref=$(echo $oldref | sed -e 's/remotes\/tags/tags/')
            elif [[ $oldref =~ remotes ]]
            then
                newref=$(echo $oldref | sed -e 's/remotes/heads/')
            fi

            if [[ $newref =~ br_alt_excel ]]
            then
                newref=${newref//br_alt_excel/alt_excel}
            fi

            git update-ref $newref $sha
            git update-ref -d $oldref
        fi
    done
}

function generate_filters() {
    # generate filter script for removing unnecessary files
    cat << EOF > /tmp/rm_bad_files.sh
git rm --cached -r --ignore-unmatch testcase/{TestResult,UCA_EE_Parser_Test*};
git rm --cached -r --ignore-unmatch doc/{*.docx,*.doc}
EOF

    # generate filter script for fixing commit message
    cat << 'EOF' > /tmp/fix_commit_msg.sh
perl -e 'while(<>) {print join(q/: /, split(/\s*:\s*/, $_, 2))}'
EOF

    chmod +x /tmp/rm_bad_files.sh
    chmod +x /tmp/fix_commit_msg.sh
}

function remove_filters() {
    rm /tmp/rm_bad_files.sh
    rm /tmp/fix_commit_msg.sh
}

function fix_commit_history() {
    generate_filters

    git filter-branch \
      --tag-name-filter cat \
      --index-filter /tmp/rm_bad_files.sh \
      --msg-filter /tmp/fix_commit_msg.sh \
      -- --all

    git for-each-ref --format="%(refname)" refs/original/ \
      | xargs -n 1 git update-ref -d

    remove_filters
}

function usage() {
    cat << EOF
Subversion to Git migration automation tool(v1.0beta)
  This tool automates the process to fix, cleanup after
  the repository is migrated from subversion with git-svn.
Usage:
  post_migration.sh [-g <grafts_file>] [-h]
Options:
  -g specify the grafts file to change parents of certain merge
     commits. Each line contains: sha-1 parent1-sha[ parent2-sha1]
  -h print help
EOF
}

while getopts "g:h" arg
do
    case $arg in
        g) 
            echo "$grafts_file";
            grafts_file=$OPTARG
            ;;
        h)
            usage
            exit 0
            ;;
        ?)
            echo "Invalid argument $arg"
            exit 1
            ;;
    esac
done

git_ws_dir=$(pwd)

# validate git workspace directory
if [[ ! -d .git ]]
then
    echo "Not a git directory: $git_ws_dir"
    exit 1
fi

# validate grafts file
if [[ ! -e $grafts_file ]]
then
    echo "Unable to find grafts file: $grafts_file"
    exit 2
fi


echo "Start post-migration processing..."
if [[ (-e $grafts_file) && (-f $grafts_file) ]]
then
    echo "Prepare .git/info/grafts..."
    cat $grafts_file > .git/info/grafts
fi

echo "Move refs to local name space..."
uplift_refs

echo "Fix commit history..."
fix_commit_history

echo "Cleanup .git directory..."
clean_up

echo "Completed post-migration processing."

# vim: set ai nu nobk expandtab sw=4 ts=4 syntax=sh:

This revision moves the inline filter commands to separate shell scripts for better code readability. No functional changes are introduced.

Make the here doc not interpolative to generate correct perl script to tidy the commit message.

Hi schnell18,

Today I used your script to want to amend losing merge history restore when migrating repository from SVN to Git. When I execute the script, an error thrown:

./svn_to_git_post_migration.sh: line 15: conditional binary operator expected
./svn_to_git_post_migration.sh: line 15: syntax error near =~' ./svn_to_git_post_migration.sh: line 15: if [[ $oldref =~ 'remotes' ]];
then'

My Git Bash is 1.8.3.

Thanks

Hi patdong,
This script is specific to my project. You can not expect it meets your need out-of-box.

Regarding the fix merge history part, you need come up the right grafts file and run the git branch-filter --tag-name-filter as in my script.

The problem you came across was reported by my colleague as well. Using a recent version of bash should resolve this problem.

Thanks for try this script and good luck with your task!