linkgit:git-config[1].

`GIT_SEQUENCE_EDITOR`::
	This environment variable overrides the configured Git editor
	when editing the todo list of an interactive rebase. See also
	linkgit:git-rebase[1] and the `sequence.editor` option in
	linkgit:git-config[1].

`GIT_SSH`::
`GIT_SSH_COMMAND`::
	If either of these environment variables is set then 'git fetch'
	and 'git push' will use the specified command instead of 'ssh'
	when they need to connect to a remote system.
	The command-line parameters passed to the configured command are
	determined by the ssh variant.  See `ssh.variant` option in
	linkgit:git-config[1] for details.
+
`$GIT_SSH_COMMAND` takes precedence over `$GIT_SSH`, and is interpreted
by the shell, which allows additional arguments to be included.
`$GIT_SSH` on the other hand must be just the path to a program
(which can be a wrapper shell script, if additional arguments are
needed).
+
Usually it is easier to configure any desired options through your
personal `.ssh/config` file.  Please consult your ssh documentation
for further details.

`GIT_SSH_VARIANT`::
	If this environment variable is set, it overrides Git's autodetection
	whether `GIT_SSH`/`GIT_SSH_COMMAND`/`core.sshCommand` refer to OpenSSH,
	plink or tortoiseplink. This variable overrides the config setting
	`ssh.variant` that serves the same purpose.

`GIT_SSL_NO_VERIFY`::
	Setting and exporting this environment variable to any value
	tells Git not to verify the SSL certificate when fetching or
	pushing over HTTPS.

`GIT_ATTR_SOURCE`::
	Sets the treeish that gitattributes will be read from.

`GIT_ASKPASS`::
	If this environment variable is set, then Git commands which need to
	acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
	will call this program with a suitable prompt as command-line argument
	and read the password from its STDOUT. See also the `core.askPass`
	option in linkgit:git-config[1].

`GIT_TERMINAL_PROMPT`::
	If this Boolean environment variable is set to false, git will not prompt
	on the terminal (e.g., when asking for HTTP authentication).

`GIT_CONFIG_GLOBAL`::
`GIT_CONFIG_SYSTEM`::
	Take the configuration from the given files instead from global or
	system-level configuration files. If `GIT_CONFIG_SYSTEM` is set, the
	system config file defined at build time (usually `/etc/gitconfig`)
	will not be read. Likewise, if `GIT_CONFIG_GLOBAL` is set, neither
	`$HOME/.gitconfig` nor `$XDG_CONFIG_HOME/git/config` will be read. Can
	be set to `/dev/null` to skip reading configuration files of the
	respective level.

`GIT_CONFIG_NOSYSTEM`::
	Whether to skip reading settings from the system-wide
	`$(prefix)/etc/gitconfig` file.  This Boolean environment variable can
	be used along with `$HOME` and `$XDG_CONFIG_HOME` to create a
	predictable environment for a picky script, or you can set it
	to true to temporarily avoid using a buggy `/etc/gitconfig` file while
	waiting for someone with sufficient permissions to fix it.

`GIT_FLUSH`::
	If this Boolean environment variable is set to true, then commands such
	as 'git blame' (in incremental mode), 'git rev-list', 'git log',
	'git check-attr' and 'git check-ignore' will
	force a flush of the output stream after each record have been
	flushed. If this
	variable is set to false, the output of these commands will be done
	using completely buffered I/O.   If this environment variable is
	not set, Git will choose buffered or record-oriented flushing
	based on whether stdout appears to be redirected to a file or not.

`GIT_TRACE`::
	Enables general trace messages, e.g. alias expansion, built-in
	command execution and external command execution.
+
If this variable is set to "1", "2" or "true" (comparison
is case insensitive), trace messages will be printed to
stderr.
+
If the variable is set to an integer value greater than 2
and lower than 10 (strictly) then Git will interpret this
value as an open file descriptor and will try to write the
trace messages into this file descriptor.
+
Alternatively,