Git

2015-05-18
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this needs to be cleaned up

Git-Logo-1788C.png

(on Wikipedia)
https://www.git-scm.com/  [ 1 ] 

A version control system of some note.

I use it, not that I know what I'm doing.

See also:



TODO - learn how to do change reviewing

Repository hosting websites:

--

Table of Contents [hide]

Tools ∞

  • gitk - While rather awful, it lets you do at least basic things.

Usage and troubleshooting ∞

  • 2009-01-16 - Having trouble cloning a repository? I got chdir "permission denied" errors. I had to install git-core.

    • (distribution not recorded)

  • Check out a single remote file

    • git checkout origin -- FILENAME

Identifying yourself ∞

Stuff will go in .git/config

If you screw this up, even after the fact, see Change the "Author" entry in the changelog.

For only the current repository ∞

git  config  --global user.email "you@example.com"
git  config  --global user.name "Your Name"

For all repositories that aren't specifically-set ∞

git  config  --global user.email "you@example.com"
git  config  --global user.name "Your Name"

Tagging ∞

git  tag "v1.3"
git  push --tags

This provides a new package to download.

Rename a tag ∞

I am told it is the following, but for me it only deleted the old tag!

OLD_TAG="some text"
NEW_TAG="some text"

git push origin refs/tags/"$OLD_TAG":refs/tags/"$NEW_TAG" :refs/tags/"$OLD_TAG"
git tag -d "$OLD_TAG"

Download everything fresh ∞

Downloading everything fresh. Maybe after accepting a pull request.

git  pull git@github.com:spiralofhope/shoes-contrib.git master

Revisionism ∞

Change the last commit message ∞

git  commit --amend

Change an older commit message ∞

Unexplored:

https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/changing-a-commit-message  [ 2 ]   [ 3 ]   [ 4 ]   [ 5 ] 

Go back in time - checkout a previous version ∞

git  log
git  checkout  <code>

to return:

git  pull  origin  HEAD

Roll back all files to a previous commit ∞

git reset --hard <tag/branch/commit id>

If you wish to commit that state, so remote repository also points to rolled back commit do:

git push <reponame> -f

You can also do something simple like roll back to the previous commit:

git reset --hard HEAD~1

Roll the repository back a little ∞

Screwed up a commit and want to roll back a little?

git  rebase  -i  HEAD^^

.. where the number of carats (^) is the number you wish to roll back.

Then within the editor, delete any lines you want to excise from git's history. Each line represents a particular commit.

Be aware that this can delete files from the disk.

Forgot to check in an old revision of a file ∞

See also https://stackoverflow.com/questions/3895453/how-do-i-make-a-git-commit-in-the-past

Well there's no easy way. It's probably doable but I can't find a solution.

The closest I get is an incomplete solution: https://web.archive.org/web/20181009092446/http://blog.xkoder.com:80/2009/06/06/git-tutorial-part-ii-sharpen-you-git-fu-with-10-more-commands/

Find the commit hash before the file you want to modify, then check it out.

git  checkout COMMIT_HASH

Make your changes, then commit them.

git  commit -a

FIXME ... then supposedly there's a way to propagate the changes back to the master's HEAD. Fucked if I know how. The above link doesn't actually explain that. I am disappoint.

Go back to the present.

git  checkout master

Remove all trace of a file ∞

BFG Repo-Cleaner

Change the "Author" entry in the changelog ∞

For git log, change the editor field.

Renaming/deleting tags on GitHub ∞

Deleting using the GitHub UI:

  1. Visit your repository

  2. Find the row: Commits | Branch | Releases | Contributor, click releases

    • You will see a list of all releases.
  3. At the top-left, Releases | Tags, click Tags
  4. Click on the name of one of the releases

  5. At the top-right, Edit release | Delete

Synchroninzing your github tag deletion to your local git repository:

git tag -l | xargs git tag -d
git fetch

Renaming a tag in a local git repository:

NEW_TAG_NAME=newtag
OLD_TAG_NAME=oldtag

git  tag  $NEW_TAG_NAME      $OLD_TAG_NAME
git  tag  -d                 $OLD_TAG_NAME
git  push origin  :refs/tags/$OLD_TAG_NAME
git  push   --tags

Restore a file deleted from git ∞

List all deleted files ∞

git  log  --diff-filter=D  --summary

Un-commit a single deleted file ∞

git  checkout  --  filename.ext

Roll back an individual file ∞

git  log  filename.ext
git  checkout  <revision>  filename.ext

For example:

git  log  filename.ext

 commit 875465be775031545f9c7f89as8025373df63e23
 Author: AUTHORNAME
 Date:   Sun Jul 19 01:20:11 2015 -0700
 
     .
 
 commit 8409d2b3aaff1276c1266748397fe3d6e9576961
 Author: AUTHORNAME
 Date:   Thu Jul 2 10:54:37 2015 -0700
 
   misc, theme updates, media locally cached

git  checkout  4d0f80012abfe9d074db841ae36f07f0722f31c8  --  filename.ext

Why there isn't a git checkout -1 -- filename.ext - type command is beyond me. I think maybe that's HEAD~1 but I haven't tested this.

I was told the right command was git checkout <filename> -1 but that didn't work..

There is also git reset

See also:

Repository maintenance - compression / optimization ∞

I don't understand these things, but they do stuff and things and that's good. Probably.

git  fsck
git  gc

(gc will fix shit that fsck finds)

Actually add files ∞

I don't know what fucking idiot would have git add -A not work as expected, but this seems to work:

git  rm --cached -r  directory
git  add             directory

Undo a git add (before doing a git commit) ∞

git  reset

Ignoring files ∞

If you want to remove all trace of a file, including from git history, see Remove all trace of a file.

https://git-scm.com/docs/gitignore

$HOME/.config/git/ignore
$GIT_DIR/info/exclude
.gitignore

Spoiler

# Lines beginning with "#" are ignored (they are comments)

# Something very specific:
/directory/file

# When the beginning / is absent then the pattern is relative to this .gitignore:
directory/file

# All files and directories from within that directory:
/directory/**

# Any file called "filenames" in any directory/subdirectory:
/**/filenames

# A file in the same place as this .gitignore:
file

# A file in the root of the git repository:
/file

# Some advanced stuff:
[fF]ile
?ile

Synchronize clone with its repository file creation times ∞

https://github.com/tst2005/git-timesync/
(archived)

When you make a git clone the created file are the current date. This script allow you to change the file timestamp to the same than the repository one.

Compare local edits ∞

git  show  HEAD:filename.ext | \wc  --bytes
Compare the change between commits
commit1="HEAD"
commit2="HEAD^"
filename="filename.ext"
source=$( git  show  "$commit1":"$filename"  |  \wc  --bytes )
target=$( git  show  "$commit2":"$filename"  |  \wc  --bytes )
\echo  "( $source - $target )" | \bc

Compare local edit to remote change ∞

Changes to all files ∞

git  diff

  • Difference between remote and local file

    • git diff origin/master -- FILENAME
    • Ignore whitespace with git diff -b origin/master -- FILENAME

  • Difference between two commits

    • e.g. this commit and the previous one: git diff HEAD HEAD^

  • Difference between local and remote repositories

    • git diff master origin/master

If you use an external tool like Diffuse, then instead use git difftool.

Changes to a specific file ∞

https://stackoverflow.com/questions/17688594/how-to-diff-between-local-uncommitted-changes-and-origin/31703666#31703666

git  diff origin/master:./ -- README.md
git  diff HEAD^:./ -- README.md
git  diff stash@{0}:./ -- README.md
git  diff 1A2B3C4D:./ -- README.md

Visually ∞

Not tested, vi is insane:

https://stackoverflow.com/questions/17688594/how-to-diff-between-local-uncommitted-changes-and-origin/34180341#34180341

git  difftool

It will start your diff app automatically for each changed file.

Windows: If you did not set a diff app, you can do it like in the example below(I use Winmerge):

git  config --global merge.tool winmerge
git  config --replace --global mergetool.winmerge.cmd \
  "\"C:\Program Files (x86)\WinMerge\WinMergeU.exe\" -e -u -dl \"Base\" -dr \"Mine\" \"$LOCAL\" \"$REMOTE\" \"$MERGED\""
git  config --global mergetool.prompt false

Split a directory into its own repository ∞

2017-08-30

folder=my_folder
branch=master
git  filter-branch \
  --prune-empty \
  --subdirectory-filter "$folder" \
  "$branch" \
` # `

You may need to edit .git/config to update url or other settings.

If you intend to host this repository on GitHub, then follow their new repository creation documentation and see also GitHub's documentation on splitting a subfolder out into a new repository.

git fsck shows dangling tree ∞

git fsck
Spoiler

Checking object directories: 100% (256/256), done.
Checking objects: 100% (9845/9845), done.
dangling tree 128e5356316731484ca660822ddd4a981b142773
dangling tree b2adbe017562c32ff31f49946b18c6af23571427
dangling tree 6bb337c6e8f591529c1a628e805c6c6f9a14e0dd
dangling tree 8941163d26e37602010799648002db75a0efd0b5
dangling tree b7ce9b153e11f6b123e818aa246f81a072d5689b
dangling tree 6cf417ae0cf811c982171c2082d4ff2c747477aa

This was seen after I did a Split a directory into its own repository.

I've now worked on that repository for some time now, without addressing this.

Failed solutions:

  • git gc

Notes:

example .gitattributes ∞

*.lua	filter=trimTrailingSpaces
*.xml	filter=trimTrailingSpaces
*.toc	filter=trimTrailingSpaces

Remove "warning: LF will be replaced by CRLF in" ∞

git  config  core.safecrlf false

Fix ESC[33m and ESC[m and restore colour ∞

git  config  --global  core.pager "less -r"

Fix the default git push ∞

Cloned something and want to fix its default push?

git  remote rm origin 
git  remote add origin git://github.com/spiralofhope/shoes.git

.. hrm, not working right, try editing .git/config and changing the url line to something like git@github.com:spiralofhope/random-shoes.git

"error: Your local changes to the following files would be overwritten by merge:" ∞

git checkout HEAD^ FILENAME

error: readlink("path/to/filename"): Function not implemented
error: unable to index file path/to/filename
fatal: updating files failed

https://stackoverflow.com/questions/11728882/how-to-get-git-on-windows-to-ignore-symbolic-links#comment56217354_11728882

git config core.symlinks true instead of git config core.symlinks false got rid of the error for me. Consequently, the symlinks I created using mklink in Windows were pushed without error, but when cloning the project again, the symlinks become text files that says where the original files are located instead of working as a real symlink.

Tested 2016-07-20 with 2.9.0.windows.1 - it seems to work.

.git/config has url = with an email address as a username (contains an at (@) symbol ∞

If git push fails because you're trying to use an email address as a username, which is set in your .git/config file, then..

Tested 2019-09-05 with Git 2.11.0 using GitHub.

Use %40 instead of the @ in your email address. E.g. if your username is email@example.com you would instead use email%40example.com like so:

[remote "origin"]
        url = https://email%40example.com@github.com/githubusername/repository-name.git

git gc gives "suboptimal pack - out of memory" ∞

If doing a git gc you get:

warning: suboptimal pack - out of memory
fatal: Out of memory, malloc failed (tried to allocate 125098831 bytes)
error: failed to run repack
git  config  pack.windowMemory  256m

If you wish to avoid this problem in the future, try performing the git gc after every significant change.

git gc gives rename errors ∞

This will occur if you use sudo or if you are trying to work with the files within Linux when they are hosted on Windows. This was reproduced on a Linux guest inside of a VirtualBox Windows 10 host, and fixed by performing the command from within Windows 10 in Windows Subsystem for Linux.

Export the repository as a zip archive ∞

git  archive  --output  ../zipfile.zip  master

Export a repository at a specific commit as a zip archive ∞

git  archive  --output  ../zipfile.zip  REVISION_ID

You can find the revision ID with git log.

Ignore everything, but allow certain file extensions ∞

For .gitignore

# Ignore everything:
*

# Actually allow subdirectories:
!/*

# Actually allow these file extensions in any subdirectory:
!*.ext

Test with:

\nano  ./.gitignore ; \git add  --dry-run  --verbose  **/*

Append a second git repository ∞

https://stackoverflow.com/questions/69869039/how-do-i-append-a-second-git-repository

Reportedly:

Yes it is possible, just change the origin in the local git config. Switch back to the original and push into the changes which have occurred since you left.

git config --local --edit

After you initialize the new repository and push up the current code.

Resources ∞

Footnotes

  1. was http://git.or.cz - [↩]
  2. was https://docs.github.com/en/github/committing-changes-to-your-project/creating-and-editing-commits/changing-a-commit-message - [↩]
  3. was https://docs.github.com/en/github/committing-changes-to-your-project/changing-a-commit-message - [↩]
  4. was https://docs.github.com/en/free-pro-team@latest/github/committing-changes-to-your-project/changing-a-commit-message - [↩]
  5. was https://help.github.com/en/github/committing-changes-to-your-project/changing-a-commit-message - [↩]
  6. was https://stackoverflow.com/questions/2733873/reverting-a-single-file-to-a-previous-version-in-git - [↩]
  7. was https://stackoverflow.com/questions/215718/how-can-i-reset-or-revert-a-file-to-a-specific-revision - [↩]
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