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:
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.gitprotocol=https
host=example.com
username=bob
password=secr3tIn 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.
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
host
path
username
password
password_expiry_utc
oauth_refresh_token
url
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 value should not be sent unless the appropriate capability (see below) is provided on input.
credential
This value should not be sent unless the appropriate capability (see below) is provided on input.
ephemeral
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 should not be sent unless the appropriate capability (see below) is provided on input.
continue
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[]
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[]
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