6 git-credential - Retrieve and store user credentials
11 'git credential' (fill|approve|reject)
17 Git has an internal interface for storing and retrieving credentials
18 from system-specific helpers, as well as prompting the user for
19 usernames and passwords. The git-credential command exposes this
20 interface to scripts which may want to retrieve, store, or prompt for
21 credentials in the same manner as Git. The design of this scriptable
22 interface models the internal C API; see credential.h for more
23 background on the concepts.
25 git-credential takes an "action" option on the command-line (one of
26 `fill`, `approve`, or `reject`) and reads a credential description
27 on stdin (see <<IOFMT,INPUT/OUTPUT FORMAT>>).
29 If the action is `fill`, git-credential will attempt to add "username"
30 and "password" attributes to the description by reading config files,
31 by contacting any configured credential helpers, or by prompting the
32 user. The username and password attributes of the credential
33 description are then printed to stdout together with the attributes
36 If the action is `approve`, git-credential will send the description
37 to any configured credential helpers, which may store the credential
40 If the action is `reject`, git-credential will send the description to
41 any configured credential helpers, which may erase any stored
42 credentials matching the description.
44 If the action is `approve` or `reject`, no output should be emitted.
46 TYPICAL USE OF GIT CREDENTIAL
47 -----------------------------
49 An application using git-credential will typically use `git
50 credential` following these steps:
52 1. Generate a credential description based on the context.
54 For example, if we want a password for
55 `https://example.com/foo.git`, we might generate the following
56 credential description (don't forget the blank line at the end; it
57 tells `git credential` that the application finished feeding all the
64 2. Ask git-credential to give us a username and password for this
65 description. This is done by running `git credential fill`,
66 feeding the description from step (1) to its standard input. The complete
67 credential description (including the credential per se, i.e. the
68 login and password) will be produced on standard output, like:
75 In most cases, this means the attributes given in the input will be
76 repeated in the output, but Git may also modify the credential
77 description, for example by removing the `path` attribute when the
78 protocol is HTTP(s) and `credential.useHttpPath` is false.
80 If the `git credential` knew about the password, this step may
81 not have involved the user actually typing this password (the
82 user may have typed a password to unlock the keychain instead,
83 or no user interaction was done if the keychain was already
84 unlocked) before it returned `password=secr3t`.
86 3. Use the credential (e.g., access the URL with the username and
87 password from step (2)), and see if it's accepted.
89 4. Report on the success or failure of the password. If the
90 credential allowed the operation to complete successfully, then
91 it can be marked with an "approve" action to tell `git
92 credential` to reuse it in its next invocation. If the credential
93 was rejected during the operation, use the "reject" action so
94 that `git credential` will ask for a new password in its next
95 invocation. In either case, `git credential` should be fed with
96 the credential description obtained from step (2) (which also
97 contains the fields provided in step (1)).
103 `git credential` reads and/or writes (depending on the action used)
104 credential information in its standard input/output. This information
105 can correspond either to keys for which `git credential` will obtain
106 the login information (e.g. host, protocol, path), or to the actual
107 credential data to be obtained (username/password).
109 The credential is split into a set of named attributes, with one
110 attribute per line. Each attribute is specified by a key-value pair,
111 separated by an `=` (equals) sign, followed by a newline.
113 The key may contain any bytes except `=`, newline, or NUL. The value may
114 contain any bytes except newline or NUL. A line, including the trailing
115 newline, may not exceed 65535 bytes in order to allow implementations to
118 Attributes with keys that end with C-style array brackets `[]` can have
119 multiple values. Each instance of a multi-valued attribute forms an
120 ordered list of values - the order of the repeated attributes defines
121 the order of the values. An empty multi-valued attribute (`key[]=\n`)
122 acts to clear any previous entries and reset the list.
124 In all cases, all bytes are treated as-is (i.e., there is no quoting,
125 and one cannot transmit a value with newline or NUL in it). The list of
126 attributes is terminated by a blank line or end-of-file.
128 Git understands the following attributes:
132 The protocol over which the credential will be used (e.g.,
137 The remote hostname for a network credential. This includes
138 the port number if one was specified (e.g., "example.com:8088").
142 The path with which the credential will be used. E.g., for
143 accessing a remote https repository, this will be the
144 repository's path on the server.
148 The credential's username, if we already have one (e.g., from a
149 URL, the configuration, the user, or from a previously run helper).
153 The credential's password, if we are asking it to be stored.
155 `password_expiry_utc`::
157 Generated passwords such as an OAuth access token may have an expiry date.
158 When reading credentials from helpers, `git credential fill` ignores expired
159 passwords. Represented as Unix time UTC, seconds since 1970.
161 `oauth_refresh_token`::
163 An OAuth refresh token may accompany a password that is an OAuth access
164 token. Helpers must treat this attribute as confidential like the password
165 attribute. Git itself has no special behaviour for this attribute.
169 When this special attribute is read by `git credential`, the
170 value is parsed as a URL and treated as if its constituent parts
171 were read (e.g., `url=https://example.com` would behave as if
172 `protocol=https` and `host=example.com` had been provided). This
173 can help callers avoid parsing URLs themselves.
175 Note that specifying a protocol is mandatory and if the URL
176 doesn't specify a hostname (e.g., "cert:///path/to/file") the
177 credential will contain a hostname attribute whose value is an
180 Components which are missing from the URL (e.g., there is no
181 username in the example above) will be left unset.
184 This indicates that the authentication scheme in question should be used.
185 Common values for HTTP and HTTPS include `basic`, `bearer`, and `digest`,
186 although the latter is insecure and should not be used. If `credential`
187 is used, this may be set to an arbitrary string suitable for the protocol in
188 question (usually HTTP).
190 This value should not be sent unless the appropriate capability (see below) is
194 The pre-encoded credential, suitable for the protocol in question (usually
195 HTTP). If this key is sent, `authtype` is mandatory, and `username` and
196 `password` are not used. For HTTP, Git concatenates the `authtype` value and
197 this value with a single space to determine the `Authorization` header.
199 This value should not be sent unless the appropriate capability (see below) is
203 This boolean value indicates, if true, that the value in the `credential`
204 field should not be saved by the credential helper because its usefulness is
205 limited in time. For example, an HTTP Digest `credential` value is computed
206 using a nonce and reusing it will not result in successful authentication.
207 This may also be used for situations with short duration (e.g., 24-hour)
208 credentials. The default value is false.
210 The credential helper will still be invoked with `store` or `erase` so that it
211 can determine whether the operation was successful.
213 This value should not be sent unless the appropriate capability (see below) is
217 This value provides an opaque state that will be passed back to this helper
218 if it is called again. Each different credential helper may specify this
219 once. The value should include a prefix unique to the credential helper and
220 should ignore values that don't match its prefix.
222 This value should not be sent unless the appropriate capability (see below) is
226 This is a boolean value, which, if enabled, indicates that this
227 authentication is a non-final part of a multistage authentication step. This
228 is common in protocols such as NTLM and Kerberos, where two rounds of client
229 authentication are required, and setting this flag allows the credential
230 helper to implement the multistage authentication step. This flag should
231 only be sent if a further stage is required; that is, if another round of
232 authentication is expected.
234 This value should not be sent unless the appropriate capability (see below) is
235 provided on input. This attribute is 'one-way' from a credential helper to
236 pass information to Git (or other programs invoking `git credential`).
240 When an HTTP response is received by Git that includes one or more
241 'WWW-Authenticate' authentication headers, these will be passed by Git
242 to credential helpers.
244 Each 'WWW-Authenticate' header value is passed as a multi-valued
245 attribute 'wwwauth[]', where the order of the attributes is the same as
246 they appear in the HTTP response. This attribute is 'one-way' from Git
247 to pass additional information to credential helpers.
250 This signals that Git, or the helper, as appropriate, supports the capability
251 in question. This can be used to provide better, more specific data as part
252 of the protocol. A `capability[]` directive must precede any value depending
253 on it and these directives _should_ be the first item announced in the
256 There are two currently supported capabilities. The first is `authtype`, which
257 indicates that the `authtype`, `credential`, and `ephemeral` values are
258 understood. The second is `state`, which indicates that the `state[]` and
259 `continue` values are understood.
261 It is not obligatory to use the additional features just because the capability
262 is supported, but they should not be provided without the capability.
264 Unrecognised attributes and capabilities are silently discarded.
268 Part of the linkgit:git[1] suite