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git-shell

Name

git-shell - Restricted login shell for Git-only SSH access

Synopsis

chsh -s $(command -v git-shell) <user>
git clone <user>@localhost:/path/to/repo.git
ssh <user>@localhost

Description

This is a login shell for SSH accounts to provide restricted Git access. It permits execution only of server-side Git commands implementing the pull/push functionality, plus custom commands present in a subdirectory named git-shell-commands in the user’s home directory.

Commands

git shell accepts the following commands after the -c option:

git receive-pack <argument>
git upload-pack <argument>
git upload-archive <argument>: Call the corresponding server-side command to support the client’s git push, git fetch, or git archive --remote request.
cvs server: Imitate a CVS server. See git-cvsserver[1].

If a ~/git-shell-commands directory is present, git shell will also handle other, custom commands by running "git-shell-commands/<command> <arguments>" from the user’s home directory.

Interactive use

By default, the commands above can be executed only with the -c option; the shell is not interactive.

If a ~/git-shell-commands directory is present, git shell can also be run interactively (with no arguments). If a help command is present in the git-shell-commands directory, it is run to provide the user with an overview of allowed actions. Then a "git> " prompt is presented at which one can enter any of the commands from the git-shell-commands directory, or exit to close the connection.

Generally this mode is used as an administrative interface to allow users to list repositories they have access to, create, delete, or rename repositories, or change repository descriptions and permissions.

If a no-interactive-login command exists, then it is run and the interactive shell is aborted.

Example

To disable interactive logins, displaying a greeting instead:

$ chsh -s /usr/bin/git-shell
$ mkdir $HOME/git-shell-commands
$ cat >$HOME/git-shell-commands/no-interactive-login <<\EOF
#!/bin/sh
printf '%s\n' "Hi $USER! You've successfully authenticated, but I do not"
printf '%s\n' "provide interactive shell access."
exit 128
EOF
$ chmod +x $HOME/git-shell-commands/no-interactive-login