# git-credential

## NAME



           git-credential - Retrieve and store user credentials
    


## SYNOPSIS



           'git credential' (fill|approve|reject|capability)
    


## DESCRIPTION



           Git has an internal interface for storing and retrieving
           credentials from system-specific helpers, as well as prompting the
           user for usernames and passwords. The git-credential command
           exposes this interface to scripts which may want to retrieve,
           store, or prompt for credentials in the same manner as Git. The
           design of this scriptable interface models the internal C API; see
           credential.h for more background on the concepts.
    
           git-credential takes an "action" option on the command-line (one
           of **fill** , **approve** , or **reject**) and reads a credential description on
           stdin (see INPUT/OUTPUT FORMAT).
    
           If the action is **fill** , git-credential will attempt to add
           "username" and "password" attributes to the description by reading
           config files, by contacting any configured credential helpers, or
           by prompting the user. The username and password attributes of the
           credential description are then printed to stdout together with
           the attributes already provided.
    
           If the action is **approve** , git-credential will send the description
           to any configured credential helpers, which may store the
           credential for later use.
    
           If the action is **reject** , git-credential will send the description
           to any configured credential helpers, which may erase any stored
           credentials matching the description.
    
           If the action is **capability** , git-credential will announce any
           capabilities it supports to standard output.
    
           If the action is **approve** or **reject** , no output should be emitted.
    


## TYPICAL USE OF GIT CREDENTIAL



           An application using git-credential will typically use **git**
           **credential** following these steps:
    
            1. Generate a credential description based on the context.
    
               For example, if we want a password for
               **https://example.com/foo.git **, we might generate the following
               credential description (don’t forget the blank line at the
               end; it tells **git credential** that the application finished
               feeding all the information it has):
    
                   protocol=https
                   host=example.com
                   path=foo.git
    
            2. Ask git-credential to give us a username and password for this
               description. This is done by running **git credential fill** ,
               feeding the description from step (1) to its standard input.
               The complete credential description (including the credential
               per se, i.e. the login and password) will be produced on
               standard output, like:
    
                   protocol=https
                   host=example.com
                   username=bob
                   password=secr3t
    
               In most cases, this means the attributes given in the input
               will be repeated in the output, but Git may also modify the
               credential description, for example by removing the **path**
               attribute when the protocol is HTTP(s) and
               **credential.useHttpPath** is false.
    
               If the **git credential** knew about the password, this step may
               not have involved the user actually typing this password (the
               user may have typed a password to unlock the keychain instead,
               or no user interaction was done if the keychain was already
               unlocked) before it returned **password=secr3t**.
    
            3. Use the credential (e.g., access the URL with the username and
               password from step (2)), and see if it’s accepted.
    
            4. Report on the success or failure of the password. If the
               credential allowed the operation to complete successfully,
               then it can be marked with an "approve" action to tell **git**
               **credential** to reuse it in its next invocation. If the
               credential was rejected during the operation, use the "reject"
               action so that **git credential** will ask for a new password in
               its next invocation. In either case, **git credential** should be
               fed with the credential description obtained from step (2)
               (which also contains the fields provided in step (1)).
    


## INPUT/OUTPUT FORMAT



           **git credential** reads and/or writes (depending on the action used)
           credential information in its standard input/output. This
           information can correspond either to keys for which **git credential**
           will obtain the login information (e.g. host, protocol, path), or
           to the actual credential data to be obtained (username/password).
    
           The credential is split into a set of named attributes, with one
           attribute per line. Each attribute is specified by a key-value
           pair, separated by an **=**(equals) sign, followed by a newline.
    
           The key may contain any bytes except **=** , newline, or NUL. The value
           may contain any bytes except newline or NUL. A line, including the
           trailing newline, may not exceed 65535 bytes in order to allow
           implementations to parse efficiently.
    
           Attributes with keys that end with C-style array brackets [] can
           have multiple values. Each instance of a multi-valued attribute
           forms an ordered list of values - the order of the repeated
           attributes defines the order of the values. An empty multi-valued
           attribute (**key**[]**=\n**) acts to clear any previous entries and reset
           the list.
    
           In all cases, all bytes are treated as-is (i.e., there is no
           quoting, and one cannot transmit a value with newline or NUL in
           it). The list of attributes is terminated by a blank line or
           end-of-file.
    
           Git understands the following attributes:
    
           **protocol**
               The protocol over which the credential will be used (e.g.,
               **https**).
    
           **host**
               The remote hostname for a network credential. This includes
               the port number if one was specified (e.g.,
               "example.com:8088").
    
           **path**
               The path with which the credential will be used. E.g., for
               accessing a remote https repository, this will be the
               repository’s path on the server.
    
           **username**
               The credential’s username, if we already have one (e.g., from
               a URL, the configuration, the user, or from a previously run
               helper).
    
           **password**
               The credential’s password, if we are asking it to be stored.
    
           **password_expiry_utc**
               Generated passwords such as an OAuth access token may have an
               expiry date. When reading credentials from helpers, **git**
               **credential fill** ignores expired passwords. Represented as Unix
               time UTC, seconds since 1970.
    
           **oauth_refresh_token**
               An OAuth refresh token may accompany a password that is an
               OAuth access token. Helpers must treat this attribute as
               confidential like the password attribute. Git itself has no
               special behaviour for this attribute.
    
           **url**
               When this special attribute is read by **git credential** , the
               value is parsed as a URL and treated as if its constituent
               parts were read (e.g., **url=https://example.com** would behave as
               if **protocol=https** and **host=example.com** had been provided).
               This can help callers avoid parsing URLs themselves.
    
               Note that specifying a protocol is mandatory and if the URL
               doesn’t specify a hostname (e.g., "cert:///path/to/file") the
               credential will contain a hostname attribute whose value is an
               empty string.
    
               Components which are missing from the URL (e.g., there is no
               username in the example above) will be left unset.
    
           **authtype**
               This indicates that the authentication scheme in question
               should be used. Common values for HTTP and HTTPS include
               **basic** , **bearer** , and **digest** , although the latter is insecure and
               should not be used. If **credential** is used, this may be set to
               an arbitrary string suitable for the protocol in question
               (usually HTTP).
    
               This value should not be sent unless the appropriate
               capability (see below) is provided on input.
    
           **credential**
               The pre-encoded credential, suitable for the protocol in
               question (usually HTTP). If this key is sent, **authtype** is
               mandatory, and **username** and **password** are not used. For HTTP,
               Git concatenates the **authtype** value and this value with a
               single space to determine the **Authorization** header.
    
               This value should not be sent unless the appropriate
               capability (see below) is provided on input.
    
           **ephemeral**
               This boolean value indicates, if true, that the value in the
               **credential** field should not be saved by the credential helper
               because its usefulness is limited in time. For example, an
               HTTP Digest **credential** value is computed using a nonce and
               reusing it will not result in successful authentication. This
               may also be used for situations with short duration (e.g.,
               24-hour) credentials. The default value is false.
    
               The credential helper will still be invoked with **store** or
               **erase** so that it can determine whether the operation was
               successful.
    
               This value should not be sent unless the appropriate
               capability (see below) is provided on input.
    
           **state**[]
               This value provides an opaque state that will be passed back
               to this helper if it is called again. Each different
               credential helper may specify this once. The value should
               include a prefix unique to the credential helper and should
               ignore values that don’t match its prefix.
    
               This value should not be sent unless the appropriate
               capability (see below) is provided on input.
    
           **continue**
               This is a boolean value, which, if enabled, indicates that
               this authentication is a non-final part of a multistage
               authentication step. This is common in protocols such as NTLM
               and Kerberos, where two rounds of client authentication are
               required, and setting this flag allows the credential helper
               to implement the multistage authentication step. This flag
               should only be sent if a further stage is required; that is,
               if another round of authentication is expected.
    
               This value should not be sent unless the appropriate
               capability (see below) is provided on input. This attribute is
               _one-way_ from a credential helper to pass information to Git
               (or other programs invoking **git credential**).
    
           **wwwauth**[]
               When an HTTP response is received by Git that includes one or
               more _WWW-Authenticate_ authentication headers, these will be
               passed by Git to credential helpers.
    
               Each _WWW-Authenticate_ header value is passed as a multi-valued
               attribute _wwwauth[]_ , where the order of the attributes is the
               same as they appear in the HTTP response. This attribute is
               _one-way_ from Git to pass additional information to credential
               helpers.
    
           **capability**[]
               This signals that Git, or the helper, as appropriate, supports
               the capability in question. This can be used to provide
               better, more specific data as part of the protocol. A
               **capability**[] directive must precede any value depending on it
               and these directives _should_ be the first item announced in the
               protocol.
    
               There are two currently supported capabilities. The first is
               **authtype** , which indicates that the **authtype** , **credential** , and
               **ephemeral** values are understood. The second is **state** , which
               indicates that the **state**[] and **continue** values are understood.
    
               It is not obligatory to use the additional features just
               because the capability is supported, but they should not be
               provided without the capability.
    
           Unrecognised attributes and capabilities are silently discarded.
    


## CAPABILITY INPUT/OUTPUT FORMAT



           For **git credential capability** , the format is slightly different.
           First, a **version 0** announcement is made to indicate the current
           version of the protocol, and then each capability is announced
           with a line like **capability authtype**. Credential helpers may also
           implement this format, again with the **capability** argument.
           Additional lines may be added in the future; callers should ignore
           lines which they don’t understand.
    
           Because this is a new part of the credential helper protocol,
           older versions of Git, as well as some credential helpers, may not
           support it. If a non-zero exit status is received, or if the first
           line doesn’t start with the word **version** and a space, callers
           should assume that no capabilities are supported.
    
           The intention of this format is to differentiate it from the
           credential output in an unambiguous way. It is possible to use
           very simple credential helpers (e.g., inline shell scripts) which
           always produce identical output. Using a distinct format allows
           users to continue to use this syntax without having to worry about
           correctly implementing capability advertisements or accidentally
           confusing callers querying for capabilities.
    


## GIT



           Part of the git(1) suite
    


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