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git/Documentation/git-config.txt
Glen Choo 779ea9303a Documentation: define protected configuration 
For security reasons, there are config variables that are only trusted
when they are specified in certain configuration scopes, which are
sometimes referred to on-list as 'protected configuration' [1]. A future
commit will introduce another such variable, so let's define our terms
so that we can have consistent documentation and implementation.

In our documentation, define 'protected configuration' as the system,
global and command config scopes. As a shorthand, I will refer to
variables that are only respected in protected configuration as
'protected configuration only', but this term is not used in the
documentation.

This definition of protected configuration is based on whether or not
Git can reasonably protect the user by ignoring the configuration scope:

- System, global and command line config are considered protected
  because an attacker who has control over any of those can do plenty of
  harm without Git, so we gain very little by ignoring those scopes.

- On the other hand, local (and similarly, worktree) config are not
  considered protected because it is relatively easy for an attacker to
  control local config, e.g.:

  - On some shared user environments, a non-admin attacker can create a
    repository high up the directory hierarchy (e.g. C:\.git on
    Windows), and a user may accidentally use it when their PS1
    automatically invokes "git" commands.

    `safe.directory` prevents attacks of this form by making sure that
    the user intended to use the shared repository. It obviously
    shouldn't be read from the repository, because that would end up
    trusting the repository that Git was supposed to reject.

  - "git upload-pack" is expected to run in repositories that may not be
    controlled by the user. We cannot ignore all config in that
    repository (because "git upload-pack" would fail), but we can limit
    the risks by ignoring `uploadpack.packObjectsHook`.

Only `uploadpack.packObjectsHook` is 'protected configuration only'. The
following variables are intentionally excluded:

- `safe.directory` should be 'protected configuration only', but it does
  not technically fit the definition because it is not respected in the
  "command" scope. A future commit will fix this.

- `trace2.*` happens to read the same scopes as `safe.directory` because
  they share an implementation. However, this is not for security
  reasons; it is because we want to start tracing so early that
  repository-level config and "-c" are not available [2].

  This requirement is unique to `trace2.*`, so it does not makes sense
  for protected configuration to be subject to the same constraints.

[1] For example,
https://lore.kernel.org/git/6af83767-576b-75c4-c778-0284344a8fe7@github.com/
[2] https://lore.kernel.org/git/a0c89d0d-669e-bf56-25d2-cbb09b012e70@jeffhostetler.com/

Signed-off-by: Glen Choo <chooglen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-07-14 15:08:29 -07:00

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git-config(1)
=============
NAME
----
git-config - Get and set repository or global options
SYNOPSIS
--------
[verse]
'git config' [<file-option>] [--type=<type>] [--fixed-value] [--show-origin] [--show-scope] [-z|--null] <name> [<value> [<value-pattern>]]
'git config' [<file-option>] [--type=<type>] --add <name> <value>
'git config' [<file-option>] [--type=<type>] [--fixed-value] --replace-all <name> <value> [<value-pattern>]
'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get <name> [<value-pattern>]
'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] --get-all <name> [<value-pattern>]
'git config' [<file-option>] [--type=<type>] [--show-origin] [--show-scope] [-z|--null] [--fixed-value] [--name-only] --get-regexp <name-regex> [<value-pattern>]
'git config' [<file-option>] [--type=<type>] [-z|--null] --get-urlmatch <name> <URL>
'git config' [<file-option>] [--fixed-value] --unset <name> [<value-pattern>]
'git config' [<file-option>] [--fixed-value] --unset-all <name> [<value-pattern>]
'git config' [<file-option>] --rename-section <old-name> <new-name>
'git config' [<file-option>] --remove-section <name>
'git config' [<file-option>] [--show-origin] [--show-scope] [-z|--null] [--name-only] -l | --list
'git config' [<file-option>] --get-color <name> [<default>]
'git config' [<file-option>] --get-colorbool <name> [<stdout-is-tty>]
'git config' [<file-option>] -e | --edit
DESCRIPTION
-----------
You can query/set/replace/unset options with this command. The name is
actually the section and the key separated by a dot, and the value will be
escaped.
Multiple lines can be added to an option by using the `--add` option.
If you want to update or unset an option which can occur on multiple
lines, a `value-pattern` (which is an extended regular expression,
unless the `--fixed-value` option is given) needs to be given. Only the
existing values that match the pattern are updated or unset. If
you want to handle the lines that do *not* match the pattern, just
prepend a single exclamation mark in front (see also <<EXAMPLES>>),
but note that this only works when the `--fixed-value` option is not
in use.
The `--type=<type>` option instructs 'git config' to ensure that incoming and
outgoing values are canonicalize-able under the given <type>. If no
`--type=<type>` is given, no canonicalization will be performed. Callers may
unset an existing `--type` specifier with `--no-type`.
When reading, the values are read from the system, global and
repository local configuration files by default, and options
`--system`, `--global`, `--local`, `--worktree` and
`--file <filename>` can be used to tell the command to read from only
that location (see <<FILES>>).
When writing, the new value is written to the repository local
configuration file by default, and options `--system`, `--global`,
`--worktree`, `--file <filename>` can be used to tell the command to
write to that location (you can say `--local` but that is the
default).
This command will fail with non-zero status upon error. Some exit
codes are:
- The section or key is invalid (ret=1),
- no section or name was provided (ret=2),
- the config file is invalid (ret=3),
- the config file cannot be written (ret=4),
- you try to unset an option which does not exist (ret=5),
- you try to unset/set an option for which multiple lines match (ret=5), or
- you try to use an invalid regexp (ret=6).
On success, the command returns the exit code 0.
A list of all available configuration variables can be obtained using the
`git help --config` command.
[[OPTIONS]]
OPTIONS
-------
--replace-all::
Default behavior is to replace at most one line. This replaces
all lines matching the key (and optionally the `value-pattern`).
--add::
Adds a new line to the option without altering any existing
values. This is the same as providing '^$' as the `value-pattern`
in `--replace-all`.
--get::
Get the value for a given key (optionally filtered by a regex
matching the value). Returns error code 1 if the key was not
found and the last value if multiple key values were found.
--get-all::
Like get, but returns all values for a multi-valued key.
--get-regexp::
Like --get-all, but interprets the name as a regular expression and
writes out the key names. Regular expression matching is currently
case-sensitive and done against a canonicalized version of the key
in which section and variable names are lowercased, but subsection
names are not.
--get-urlmatch <name> <URL>::
When given a two-part name section.key, the value for
section.<URL>.key whose <URL> part matches the best to the
given URL is returned (if no such key exists, the value for
section.key is used as a fallback). When given just the
section as name, do so for all the keys in the section and
list them. Returns error code 1 if no value is found.
--global::
For writing options: write to global `~/.gitconfig` file
rather than the repository `.git/config`, write to
`$XDG_CONFIG_HOME/git/config` file if this file exists and the
`~/.gitconfig` file doesn't.
+
For reading options: read only from global `~/.gitconfig` and from
`$XDG_CONFIG_HOME/git/config` rather than from all available files.
+
See also <<FILES>>.
--system::
For writing options: write to system-wide
`$(prefix)/etc/gitconfig` rather than the repository
`.git/config`.
+
For reading options: read only from system-wide `$(prefix)/etc/gitconfig`
rather than from all available files.
+
See also <<FILES>>.
--local::
For writing options: write to the repository `.git/config` file.
This is the default behavior.
+
For reading options: read only from the repository `.git/config` rather than
from all available files.
+
See also <<FILES>>.
--worktree::
Similar to `--local` except that `$GIT_DIR/config.worktree` is
read from or written to if `extensions.worktreeConfig` is
enabled. If not it's the same as `--local`. Note that `$GIT_DIR`
is equal to `$GIT_COMMON_DIR` for the main working tree, but is of
the form `$GIT_DIR/worktrees/<id>/` for other working trees. See
linkgit:git-worktree[1] to learn how to enable
`extensions.worktreeConfig`.
-f <config-file>::
--file <config-file>::
For writing options: write to the specified file rather than the
repository `.git/config`.
+
For reading options: read only from the specified file rather than from all
available files.
+
See also <<FILES>>.
--blob <blob>::
Similar to `--file` but use the given blob instead of a file. E.g.
you can use 'master:.gitmodules' to read values from the file
'.gitmodules' in the master branch. See "SPECIFYING REVISIONS"
section in linkgit:gitrevisions[7] for a more complete list of
ways to spell blob names.
--remove-section::
Remove the given section from the configuration file.
--rename-section::
Rename the given section to a new name.
--unset::
Remove the line matching the key from config file.
--unset-all::
Remove all lines matching the key from config file.
-l::
--list::
List all variables set in config file, along with their values.
--fixed-value::
When used with the `value-pattern` argument, treat `value-pattern` as
an exact string instead of a regular expression. This will restrict
the name/value pairs that are matched to only those where the value
is exactly equal to the `value-pattern`.
--type <type>::
'git config' will ensure that any input or output is valid under the given
type constraint(s), and will canonicalize outgoing values in `<type>`'s
canonical form.
+
Valid `<type>`'s include:
+
- 'bool': canonicalize values as either "true" or "false".
- 'int': canonicalize values as simple decimal numbers. An optional suffix of
'k', 'm', or 'g' will cause the value to be multiplied by 1024, 1048576, or
1073741824 upon input.
- 'bool-or-int': canonicalize according to either 'bool' or 'int', as described
above.
- 'path': canonicalize by adding a leading `~` to the value of `$HOME` and
`~user` to the home directory for the specified user. This specifier has no
effect when setting the value (but you can use `git config section.variable
~/` from the command line to let your shell do the expansion.)
- 'expiry-date': canonicalize by converting from a fixed or relative date-string
to a timestamp. This specifier has no effect when setting the value.
- 'color': When getting a value, canonicalize by converting to an ANSI color
escape sequence. When setting a value, a sanity-check is performed to ensure
that the given value is canonicalize-able as an ANSI color, but it is written
as-is.
+
--bool::
--int::
--bool-or-int::
--path::
--expiry-date::
Historical options for selecting a type specifier. Prefer instead `--type`
(see above).
--no-type::
Un-sets the previously set type specifier (if one was previously set). This
option requests that 'git config' not canonicalize the retrieved variable.
`--no-type` has no effect without `--type=<type>` or `--<type>`.
-z::
--null::
For all options that output values and/or keys, always
end values with the null character (instead of a
newline). Use newline instead as a delimiter between
key and value. This allows for secure parsing of the
output without getting confused e.g. by values that
contain line breaks.
--name-only::
Output only the names of config variables for `--list` or
`--get-regexp`.
--show-origin::
Augment the output of all queried config options with the
origin type (file, standard input, blob, command line) and
the actual origin (config file path, ref, or blob id if
applicable).
--show-scope::
Similar to `--show-origin` in that it augments the output of
all queried config options with the scope of that value
(worktree, local, global, system, command).
--get-colorbool <name> [<stdout-is-tty>]::
Find the color setting for `<name>` (e.g. `color.diff`) and output
"true" or "false". `<stdout-is-tty>` should be either "true" or
"false", and is taken into account when configuration says
"auto". If `<stdout-is-tty>` is missing, then checks the standard
output of the command itself, and exits with status 0 if color
is to be used, or exits with status 1 otherwise.
When the color setting for `name` is undefined, the command uses
`color.ui` as fallback.
--get-color <name> [<default>]::
Find the color configured for `name` (e.g. `color.diff.new`) and
output it as the ANSI color escape sequence to the standard
output. The optional `default` parameter is used instead, if
there is no color configured for `name`.
+
`--type=color [--default=<default>]` is preferred over `--get-color`
(but note that `--get-color` will omit the trailing newline printed by
`--type=color`).
-e::
--edit::
Opens an editor to modify the specified config file; either
`--system`, `--global`, or repository (default).
--[no-]includes::
Respect `include.*` directives in config files when looking up
values. Defaults to `off` when a specific file is given (e.g.,
using `--file`, `--global`, etc) and `on` when searching all
config files.
--default <value>::
When using `--get`, and the requested variable is not found, behave as if
<value> were the value assigned to the that variable.
CONFIGURATION
-------------
`pager.config` is only respected when listing configuration, i.e., when
using `--list` or any of the `--get-*` which may return multiple results.
The default is to use a pager.
[[FILES]]
FILES
-----
By default, 'git config' will read configuration options from multiple
files:
$(prefix)/etc/gitconfig::
System-wide configuration file.
$XDG_CONFIG_HOME/git/config::
~/.gitconfig::
User-specific configuration files. When the XDG_CONFIG_HOME environment
variable is not set or empty, $HOME/.config/ is used as
$XDG_CONFIG_HOME.
+
These are also called "global" configuration files. If both files exist, both
files are read in the order given above.
$GIT_DIR/config::
Repository specific configuration file.
$GIT_DIR/config.worktree::
This is optional and is only searched when
`extensions.worktreeConfig` is present in $GIT_DIR/config.
You may also provide additional configuration parameters when running any
git command by using the `-c` option. See linkgit:git[1] for details.
Options will be read from all of these files that are available. If the
global or the system-wide configuration files are missing or unreadable they
will be ignored. If the repository configuration file is missing or unreadable,
'git config' will exit with a non-zero error code. An error message is produced
if the file is unreadable, but not if it is missing.
The files are read in the order given above, with last value found taking
precedence over values read earlier. When multiple values are taken then all
values of a key from all files will be used.
By default, options are only written to the repository specific
configuration file. Note that this also affects options like `--replace-all`
and `--unset`. *'git config' will only ever change one file at a time*.
You can limit which configuration sources are read from or written to by
specifying the path of a file with the `--file` option, or by specifying a
configuration scope with `--system`, `--global`, `--local`, or `--worktree`.
For more, see <<OPTIONS>> above.
[[SCOPES]]
SCOPES
------
Each configuration source falls within a configuration scope. The scopes
are:
system::
$(prefix)/etc/gitconfig
global::
$XDG_CONFIG_HOME/git/config
+
~/.gitconfig
local::
$GIT_DIR/config
worktree::
$GIT_DIR/config.worktree
command::
GIT_CONFIG_{COUNT,KEY,VALUE} environment variables (see <<ENVIRONMENT>>
below)
+
the `-c` option
With the exception of 'command', each scope corresponds to a command line
option: `--system`, `--global`, `--local`, `--worktree`.
When reading options, specifying a scope will only read options from the
files within that scope. When writing options, specifying a scope will write
to the files within that scope (instead of the repository specific
configuration file). See <<OPTIONS>> above for a complete description.
Most configuration options are respected regardless of the scope it is
defined in, but some options are only respected in certain scopes. See the
respective option's documentation for the full details.
Protected configuration
~~~~~~~~~~~~~~~~~~~~~~~
Protected configuration refers to the 'system', 'global', and 'command' scopes.
For security reasons, certain options are only respected when they are
specified in protected configuration, and ignored otherwise.
Git treats these scopes as if they are controlled by the user or a trusted
administrator. This is because an attacker who controls these scopes can do
substantial harm without using Git, so it is assumed that the user's environment
protects these scopes against attackers.
[[ENVIRONMENT]]
ENVIRONMENT
-----------
GIT_CONFIG_GLOBAL::
GIT_CONFIG_SYSTEM::
Take the configuration from the given files instead from global or
system-level configuration. See linkgit:git[1] for details.
GIT_CONFIG_NOSYSTEM::
Whether to skip reading settings from the system-wide
$(prefix)/etc/gitconfig file. See linkgit:git[1] for details.
See also <<FILES>>.
GIT_CONFIG_COUNT::
GIT_CONFIG_KEY_<n>::
GIT_CONFIG_VALUE_<n>::
If GIT_CONFIG_COUNT is set to a positive number, all environment pairs
GIT_CONFIG_KEY_<n> and GIT_CONFIG_VALUE_<n> up to that number will be
added to the process's runtime configuration. The config pairs are
zero-indexed. Any missing key or value is treated as an error. An empty
GIT_CONFIG_COUNT is treated the same as GIT_CONFIG_COUNT=0, namely no
pairs are processed. These environment variables will override values
in configuration files, but will be overridden by any explicit options
passed via `git -c`.
+
This is useful for cases where you want to spawn multiple git commands
with a common configuration but cannot depend on a configuration file,
for example when writing scripts.
GIT_CONFIG::
If no `--file` option is provided to `git config`, use the file
given by `GIT_CONFIG` as if it were provided via `--file`. This
variable has no effect on other Git commands, and is mostly for
historical compatibility; there is generally no reason to use it
instead of the `--file` option.
[[EXAMPLES]]
EXAMPLES
--------
Given a .git/config like this:
------------
#
# This is the config file, and
# a '#' or ';' character indicates
# a comment
#
; core variables
[core]
; Don't trust file modes
filemode = false
; Our diff algorithm
[diff]
external = /usr/local/bin/diff-wrapper
renames = true
; Proxy settings
[core]
gitproxy=proxy-command for kernel.org
gitproxy=default-proxy ; for all the rest
; HTTP
[http]
sslVerify
[http "https://weak.example.com"]
sslVerify = false
cookieFile = /tmp/cookie.txt
------------
you can set the filemode to true with
------------
% git config core.filemode true
------------
The hypothetical proxy command entries actually have a postfix to discern
what URL they apply to. Here is how to change the entry for kernel.org
to "ssh".
------------
% git config core.gitproxy '"ssh" for kernel.org' 'for kernel.org$'
------------
This makes sure that only the key/value pair for kernel.org is replaced.
To delete the entry for renames, do
------------
% git config --unset diff.renames
------------
If you want to delete an entry for a multivar (like core.gitproxy above),
you have to provide a regex matching the value of exactly one line.
To query the value for a given key, do
------------
% git config --get core.filemode
------------
or
------------
% git config core.filemode
------------
or, to query a multivar:
------------
% git config --get core.gitproxy "for kernel.org$"
------------
If you want to know all the values for a multivar, do:
------------
% git config --get-all core.gitproxy
------------
If you like to live dangerously, you can replace *all* core.gitproxy by a
new one with
------------
% git config --replace-all core.gitproxy ssh
------------
However, if you really only want to replace the line for the default proxy,
i.e. the one without a "for ..." postfix, do something like this:
------------
% git config core.gitproxy ssh '! for '
------------
To actually match only values with an exclamation mark, you have to
------------
% git config section.key value '[!]'
------------
To add a new proxy, without altering any of the existing ones, use
------------
% git config --add core.gitproxy '"proxy-command" for example.com'
------------
An example to use customized color from the configuration in your
script:
------------
#!/bin/sh
WS=$(git config --get-color color.diff.whitespace "blue reverse")
RESET=$(git config --get-color "" "reset")
echo "${WS}your whitespace color or blue reverse${RESET}"
------------
For URLs in `https://weak.example.com`, `http.sslVerify` is set to
false, while it is set to `true` for all others:
------------
% git config --type=bool --get-urlmatch http.sslverify https://good.example.com
true
% git config --type=bool --get-urlmatch http.sslverify https://weak.example.com
false
% git config --get-urlmatch http https://weak.example.com
http.cookieFile /tmp/cookie.txt
http.sslverify false
------------
include::config.txt[]
BUGS
----
When using the deprecated `[section.subsection]` syntax, changing a value
will result in adding a multi-line key instead of a change, if the subsection
is given with at least one uppercase character. For example when the config
looks like
--------
[section.subsection]
key = value1
--------
and running `git config section.Subsection.key value2` will result in
--------
[section.subsection]
key = value1
key = value2
--------
GIT
---
Part of the linkgit:git[1] suite
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