This answer provide interesting commands based on git am and presented using examples, step by step.
Objective
- You want to move some or all files from one repository to another.
- You want to keep their history.
- But you do not care about keeping tags and branches.
- You accept limited history for renamed files (and files in renamed directories).
Procedure
- Extract history in email format using
git log --pretty=email -p --reverse --full-index --binary
- Reorganize file tree and update filename change in history [optional]
- Apply new history using
git am
1. Extract history in email format
Example: Extract history of file3, file4 and file5
my_repo
├── dirA
│ ├── file1
│ └── file2
├── dirB ^
│ ├── subdir | To be moved
│ │ ├── file3 | with history
│ │ └── file4 |
│ └── file5 v
└── dirC
├── file6
└── file7
Clean the temporary directory destination
export historydir=/tmp/mail/dir # Absolute path
rm -rf "$historydir" # Caution when cleaning
Clean your the repo source
git commit ... # Commit your working files
rm .gitignore # Disable gitignore
git clean -n # Simulate removal
git clean -f # Remove untracked file
git checkout .gitignore # Restore gitignore
Extract history of each file in email format
cd my_repo/dirB
find -name .git -prune -o -type d -o -exec bash -c 'mkdir -p "$historydir/${0%/*}" && git log --pretty=email -p --stat --reverse --full-index --binary -- "$0" > "$historydir/$0"' {} ';'
Unfortunately option --follow or --find-copies-harder cannot be combined with --reverse. This is why history is cut when file is renamed (or when a parent directory is renamed).
After: Temporary history in email format
/tmp/mail/dir
├── subdir
│ ├── file3
│ └── file4
└── file5
2. Reorganize file tree and update filename change in history [optional]
Suppose you want to move these three files in this other repo (can be the same repo).
my_other_repo
├── dirF
│ ├── file55
│ └── file56
├── dirB # New tree
│ ├── dirB1 # was subdir
│ │ ├── file33 # was file3
│ │ └── file44 # was file4
│ └── dirB2 # new dir
│ └── file5 # = file5
└── dirH
└── file77
Therefore reorganize your files:
cd /tmp/mail/dir
mkdir dirB
mv subdir dirB/dirB1
mv dirB/dirB1/file3 dirB/dirB1/file33
mv dirB/dirB1/file4 dirB/dirB1/file44
mkdir dirB/dirB2
mv file5 dirB/dirB2
Your temporary history is now:
/tmp/mail/dir
└── dirB
├── dirB1
│ ├── file33
│ └── file44
└── dirB2
└── file5
Change also filenames within the history:
cd "$historydir"
find * -type f -exec bash -c 'sed "/^diff --git a\|^--- a\|^+++ b/s:\( [ab]\)/[^ ]*:\1/$0:g" -i "$0"' {} ';'
Note: This rewrites the history to reflect the change of path and filename.
(i.e. the change of the new location/name within the new repo)
3. Apply new history
Your other repo is:
my_other_repo
├── dirF
│ ├── file55
│ └── file56
└── dirH
└── file77
Apply commits from temporary history files:
cd my_other_repo
find "$historydir" -type f -exec cat {} + | git am
Your other repo is now:
my_other_repo
├── dirF
│ ├── file55
│ └── file56
├── dirB ^
│ ├── dirB1 | New files
│ │ ├── file33 | with
│ │ └── file44 | history
│ └── dirB2 | kept
│ └── file5 v
└── dirH
└── file77
Use git status to see amount of commits ready to be pushed :-)
Note: As the history has been rewritten to reflect the path and filename change:
(i.e. compared to the location/name within the previous repo)
- No need to
git mv to change the location/filename.
- No need to
git log --follow to access full history.
Extra trick: Detect renamed/moved files within your repo
To list the files having been renamed:
find -name .git -prune -o -exec git log --pretty=tformat:'' --numstat --follow {} ';' | grep '=>'
More customizations: You can complete the command git log using options --find-copies-harder or --reverse. You can also remove the first two columns using cut -f3- and grepping complete pattern '{.* => .*}'.
find -name .git -prune -o -exec git log --pretty=tformat:'' --numstat --follow --find-copies-harder --reverse {} ';' | cut -f3- | grep '{.* => .*}'
