# Developer Contributions to GDAL

Install all required development packages: GNU make, g++, …

Build:

    cd gdal
    ./autogen.sh
    ./configure [options]
    make -j8 -s
    cd apps; make -s test_ogrsf; cd ..

Run command line utilities (without installing):

    . scripts/setdevenv.sh
    gdalinfo --version

Run autotest suite:

    cd ../autotest
    pip install -r requirements.txt
    pytest

## Git workflows with GDAL

This is not a git tutorial or reference manual by any means. This just collects a few best practice for git usage for GDAL development.

### Commit message

Indicate a component name (eg a driver name), a short description and when relevant, a reference to a issue (with ‘fixes #’ if it actually fixes it)

    COMPONENT_NAME: fix bla bla (fixes #1234)

    Details here...

### Initiate your work repository

Fork OSGeo/GDAL from GitHub UI, and then

    git clone https://github.com/OSGeo/gdal
    cd gdal
    git remote add my_user_name https://github.com/my_user_name/gdal.git

### Updating your local master against upstream master

    git checkout master
    git fetch origin
    # Be careful: this will loose all local changes you might have done now
    git reset --hard origin/master

### Working with a feature branch

    git checkout master
    (potentially update your local master against upstream, as described above)
    git checkout -b my_new_feature_branch

    # do work. For example:
    git add my_new_file
    git add my_modifid_message
    git rm old_file
    git commit -a

    # you may need to resynchronize against master if you need some bugfix
    # or new capability that has been added since you created your branch
    git fetch origin
    git rebase origin/master

    # At end of your work, make sure history is reasonable by folding non
    # significant commits into a consistent set
    git rebase -i master (use 'fixup' for example to merge several commits together,
    and 'reword' to modify commit messages)

    # or alternatively, in case there is a big number of commits and marking
    # all them as 'fixup' is tedious
    git fetch origin
    git rebase origin/master
    git reset --soft origin/master
    git commit -a -m "Put here the synthetic commit message"

    # push your branch
    git push my_user_name my_new_feature_branch
    From GitHub UI, issue a pull request

If the pull request discussion or CI checks require changes, commit locally and push. To get a reasonable history, you may need to `git rebase -i master`, in which case you will have to force-push your branch with `git push -f my_user_name my_new_feature_branch`

### Backporting bugfixes from master to a stable branch

    git checkout master
    With git log, identify the sha1sum of the commit you want to backport
    git checkout 2.2 (if you want to backport to 2.2)
    git pull origin 2.2
    (git checkout -b branch_name: if you intend to submit the backport as a pull request)
    git cherry-pick the_sha1_sum
    git push ...

If changes are needed, do them and `git commit -a --amend`

### Things you should NOT do

(For anyone with push rights to github.com/OSGeo/gdal) Never modify a commit or the history of anything that has been committed to https://github.com/OSGeo/gdal