Bdtyktl

For example, I want to download PCL 3d_rec_framework.

This is the git repository of PCL: https://github.com/PointCloudLibrary/pcl.git

How to download this directory?

https://github.com/PointCloudLibrary/pcl/tree/master/apps

I have tried to run but not works:

sam@sam:~/code/pcl_standalone$ git clone https://github.com/PointCloudLibrary/pcl/tree/master/apps/3d_rec_framework

Cloning into '3d_rec_framework'...

error: The requested URL returned error: 403 while accessing https://github.com/PointCloudLibrary/pcl/tree/master/apps/3d_rec_framework/info/refs

fatal: HTTP request failed

sam@sam:~/code/pcl_standalone$ 

How to download it?

By the way, I don't want to download git of PCL and remove all other directories that I don't want. That's why I ask this question.

Thank you~

You cannot. With git, you clone the entire repository, and the full history of the repository.

There are some workaround solutions to be able to get a single file out of a git archive, listed on a Stack Exchange answer for the same question, but you will still have to download the entire repository to get that single file or directory you want.

dobey's answer is no longer the case since git v1.7. You can now checkout certain folders from a repository. The full instructions are found here.

git init <repo>

cd <repo>

git remote add -f origin <url>



git config core.sparseCheckout true



echo "some/dir/" >> .git/info/sparse-checkout

echo "another/sub/tree" >> .git/info/sparse-checkout

This tells git which directories you want to checkout. Then you can pull just those directories

git pull origin master

First, do:

git clone --depth 1 [repo root] [name of destination directory]

Then:

cd [name of destination directory]

...And lastly:

git filter-branch --prune-empty --subdirectory-filter [path to sub-dir] HEAD

It's that easy. Git will rewrite the repo so that only the desired sub-dir is included. This works even if the sub-dir is several layers deep. Just name the destination directory the name of the sub-dir. Then in the "git filter-branch" command put the relative path to the sub-dir. Oh, the --depth 1 tells git to only download the top of the head (essentially removing the history).

git clone --filter from Git 2.19

This option will actually skip fetching most unneeded objects from the server:

git clone --depth 1 --no-checkout --filter=blob:none 

  "file://$(pwd)/server_repo" local_repo

cd local_repo

git checkout master -- mydir/myfile

The server should be configured with:

git config --local uploadpack.allowfilter 1

git config --local uploadpack.allowanysha1inwant 1

There is no server support as of v2.19.0, but it can already be locally tested.

TODO: --filter=blob:none skips all blobs, but still fetches all tree objects. But on a normal repo, this should be tiny compared to the files themselves, so this is already good enough. Asked at: https://www.spinics.net/lists/git/msg342006.html Devs replied a --filter=tree:0 is in the works to do that.

Remember that --depth 1 already implies --single-branch, see also: https://stackoverflow.com/questions/1778088/how-to-clone-a-single-branch-in-git

file://$(path) is required to overcome git clone protocol shenanigans: https://stackoverflow.com/questions/47307578/how-to-shallow-clone-a-local-git-repository-with-a-relative-path

The format of --filter is documented on man git-rev-list.

An extension was made to the Git remote protocol to support this feature.

Docs on Git tree:

• https://github.com/git/git/blob/v2.19.0/Documentation/technical/partial-clone.txt


• https://github.com/git/git/blob/v2.19.0/Documentation/rev-list-options.txt#L720


• https://github.com/git/git/blob/v2.19.0/t/t5616-partial-clone.sh

See also: https://stackoverflow.com/questions/2466735/how-to-checkout-only-one-file-from-git-repository-sparse-checkout

Test it out

#!/usr/bin/env bash

set -eu



list-objects() (

  git rev-list --all --objects

  echo "master commit SHA: $(git log -1 --format="%H")"

  echo "mybranch commit SHA: $(git log -1 --format="%H")"

  git ls-tree master

  git ls-tree mybranch | grep mybranch

  git ls-tree master~ | grep root

)



# Reproducibility.

export GIT_COMMITTER_NAME='a'

export GIT_COMMITTER_EMAIL='a'

export GIT_AUTHOR_NAME='a'

export GIT_AUTHOR_EMAIL='a'

export GIT_COMMITTER_DATE='2000-01-01T00:00:00+0000'

export GIT_AUTHOR_DATE='2000-01-01T00:00:00+0000'



rm -rf server_repo local_repo

mkdir server_repo

cd server_repo



# Create repo.

git init --quiet

git config --local uploadpack.allowfilter 1

git config --local uploadpack.allowanysha1inwant 1



# First commit.

# Directories present in all branches.

mkdir d1 d2

printf 'd1/a' > ./d1/a

printf 'd1/b' > ./d1/b

printf 'd2/a' > ./d2/a

printf 'd2/b' > ./d2/b

# Present only in root.

mkdir 'root'

printf 'root' > ./root/root

git add .

git commit -m 'root' --quiet



# Second commit only on master.

git rm --quiet -r ./root

mkdir 'master'

printf 'master' > ./master/master

git add .

git commit -m 'master commit' --quiet



# Second commit only on mybranch.

git checkout -b mybranch --quiet master~

git rm --quiet -r ./root

mkdir 'mybranch'

printf 'mybranch' > ./mybranch/mybranch

git add .

git commit -m 'mybranch commit' --quiet



echo "# List and identify all objects"

list-objects

echo



# Restore master.

git checkout --quiet master

cd ..



# Clone. Don't checkout for now, only .git/ dir.

git clone --depth 1 --quiet --no-checkout --filter=blob:none "file://$(pwd)/server_repo" local_repo

cd local_repo



# List missing objects from master.

echo "# Missing objects after --no-checkout"

git rev-list --all --quiet --objects --missing=print

echo



echo "# Git checkout fails without internet"

mv ../server_repo ../server_repo.off

! git checkout master

echo



echo "# Git checkout fetches the missing file from internet"

mv ../server_repo.off ../server_repo

git checkout master -- d1/a

echo



echo "# Missing objects after checking out d1/a"

git rev-list --all --quiet --objects --missing=print

GitHub upstream.

Output in Git v2.19.0:

# List and identify all objects

c6fcdfaf2b1462f809aecdad83a186eeec00f9c1

fc5e97944480982cfc180a6d6634699921ee63ec

7251a83be9a03161acde7b71a8fda9be19f47128

62d67bce3c672fe2b9065f372726a11e57bade7e

b64bf435a3e54c5208a1b70b7bcb0fc627463a75 d1

308150e8fddde043f3dbbb8573abb6af1df96e63 d1/a

f70a17f51b7b30fec48a32e4f19ac15e261fd1a4 d1/b

84de03c312dc741d0f2a66df7b2f168d823e122a d2

0975df9b39e23c15f63db194df7f45c76528bccb d2/a

41484c13520fcbb6e7243a26fdb1fc9405c08520 d2/b

7d5230379e4652f1b1da7ed1e78e0b8253e03ba3 master

8b25206ff90e9432f6f1a8600f87a7bd695a24af master/master

ef29f15c9a7c5417944cc09711b6a9ee51b01d89

19f7a4ca4a038aff89d803f017f76d2b66063043 mybranch

1b671b190e293aa091239b8b5e8c149411d00523 mybranch/mybranch

c3760bb1a0ece87cdbaf9a563c77a45e30a4e30e

a0234da53ec608b54813b4271fbf00ba5318b99f root

93ca1422a8da0a9effc465eccbcb17e23015542d root/root

master commit SHA: fc5e97944480982cfc180a6d6634699921ee63ec

mybranch commit SHA: fc5e97944480982cfc180a6d6634699921ee63ec

040000 tree b64bf435a3e54c5208a1b70b7bcb0fc627463a75    d1

040000 tree 84de03c312dc741d0f2a66df7b2f168d823e122a    d2

040000 tree 7d5230379e4652f1b1da7ed1e78e0b8253e03ba3    master

040000 tree 19f7a4ca4a038aff89d803f017f76d2b66063043    mybranch

040000 tree a0234da53ec608b54813b4271fbf00ba5318b99f    root



# Missing objects after --no-checkout

?f70a17f51b7b30fec48a32e4f19ac15e261fd1a4

?8b25206ff90e9432f6f1a8600f87a7bd695a24af

?41484c13520fcbb6e7243a26fdb1fc9405c08520

?0975df9b39e23c15f63db194df7f45c76528bccb

?308150e8fddde043f3dbbb8573abb6af1df96e63



# Git checkout fails without internet

fatal: '/home/ciro/bak/git/test-git-web-interface/other-test-repos/partial-clone.tmp/server_repo' does not appear to be a git repository

fatal: Could not read from remote repository.



Please make sure you have the correct access rights

and the repository exists.



# Git checkout fetches the missing directory from internet

remote: Enumerating objects: 1, done.

remote: Counting objects: 100% (1/1), done.

remote: Total 1 (delta 0), reused 0 (delta 0)

Receiving objects: 100% (1/1), 45 bytes | 45.00 KiB/s, done.

remote: Enumerating objects: 1, done.

remote: Counting objects: 100% (1/1), done.

remote: Total 1 (delta 0), reused 0 (delta 0)

Receiving objects: 100% (1/1), 45 bytes | 45.00 KiB/s, done.



# Missing objects after checking out d1

?f70a17f51b7b30fec48a32e4f19ac15e261fd1a4

?8b25206ff90e9432f6f1a8600f87a7bd695a24af

?41484c13520fcbb6e7243a26fdb1fc9405c08520

?0975df9b39e23c15f63db194df7f45c76528bccb

Conclusions: all blobs except d1/a are missing. E.g. f70a17f51b7b30fec48a32e4f19ac15e261fd1a4, which is d1/b, is not there after checking out d1/.

Note that root/root and mybranch/mybranch are also missing, but --depth 1 hides that from the list of missing files. If you remove --depth 1, then they show on the list of missing files.