Documentation / git-credential.txton commit diff-delta: set size out-parameter to 0 for NULL delta (e4b3690)
   1git-credential(1)
   2=================
   3
   4NAME
   5----
   6git-credential - Retrieve and store user credentials
   7
   8SYNOPSIS
   9--------
  10------------------
  11git credential <fill|approve|reject>
  12------------------
  13
  14DESCRIPTION
  15-----------
  16
  17Git has an internal interface for storing and retrieving credentials
  18from system-specific helpers, as well as prompting the user for
  19usernames and passwords. The git-credential command exposes this
  20interface to scripts which may want to retrieve, store, or prompt for
  21credentials in the same manner as Git. The design of this scriptable
  22interface models the internal C API; see
  23link:technical/api-credentials.html[the Git credential API] for more
  24background on the concepts.
  25
  26git-credential takes an "action" option on the command-line (one of
  27`fill`, `approve`, or `reject`) and reads a credential description
  28on stdin (see <<IOFMT,INPUT/OUTPUT FORMAT>>).
  29
  30If the action is `fill`, git-credential will attempt to add "username"
  31and "password" attributes to the description by reading config files,
  32by contacting any configured credential helpers, or by prompting the
  33user. The username and password attributes of the credential
  34description are then printed to stdout together with the attributes
  35already provided.
  36
  37If the action is `approve`, git-credential will send the description
  38to any configured credential helpers, which may store the credential
  39for later use.
  40
  41If the action is `reject`, git-credential will send the description to
  42any configured credential helpers, which may erase any stored
  43credential matching the description.
  44
  45If the action is `approve` or `reject`, no output should be emitted.
  46
  47TYPICAL USE OF GIT CREDENTIAL
  48-----------------------------
  49
  50An application using git-credential will typically use `git
  51credential` following these steps:
  52
  53  1. Generate a credential description based on the context.
  54+
  55For example, if we want a password for
  56`https://example.com/foo.git`, we might generate the following
  57credential description (don't forget the blank line at the end; it
  58tells `git credential` that the application finished feeding all the
  59information it has):
  60
  61         protocol=https
  62         host=example.com
  63         path=foo.git
  64
  65  2. Ask git-credential to give us a username and password for this
  66     description. This is done by running `git credential fill`,
  67     feeding the description from step (1) to its standard input. The complete
  68     credential description (including the credential per se, i.e. the
  69     login and password) will be produced on standard output, like:
  70
  71        protocol=https
  72        host=example.com
  73        username=bob
  74        password=secr3t
  75+
  76In most cases, this means the attributes given in the input will be
  77repeated in the output, but Git may also modify the credential
  78description, for example by removing the `path` attribute when the
  79protocol is HTTP(s) and `credential.useHttpPath` is false.
  80+
  81If the `git credential` knew about the password, this step may
  82not have involved the user actually typing this password (the
  83user may have typed a password to unlock the keychain instead,
  84or no user interaction was done if the keychain was already
  85unlocked) before it returned `password=secr3t`.
  86
  87  3. Use the credential (e.g., access the URL with the username and
  88     password from step (2)), and see if it's accepted.
  89
  90  4. Report on the success or failure of the password. If the
  91     credential allowed the operation to complete successfully, then
  92     it can be marked with an "approve" action to tell `git
  93     credential` to reuse it in its next invocation. If the credential
  94     was rejected during the operation, use the "reject" action so
  95     that `git credential` will ask for a new password in its next
  96     invocation. In either case, `git credential` should be fed with
  97     the credential description obtained from step (2) (which also
  98     contain the ones provided in step (1)).
  99
 100[[IOFMT]]
 101INPUT/OUTPUT FORMAT
 102-------------------
 103
 104`git credential` reads and/or writes (depending on the action used)
 105credential information in its standard input/output. This information
 106can correspond either to keys for which `git credential` will obtain
 107the login/password information (e.g. host, protocol, path), or to the
 108actual credential data to be obtained (login/password).
 109
 110The credential is split into a set of named attributes, with one
 111attribute per line. Each attribute is
 112specified by a key-value pair, separated by an `=` (equals) sign,
 113followed by a newline. The key may contain any bytes except `=`,
 114newline, or NUL. The value may contain any bytes except newline or NUL.
 115In both cases, all bytes are treated as-is (i.e., there is no quoting,
 116and one cannot transmit a value with newline or NUL in it). The list of
 117attributes is terminated by a blank line or end-of-file.
 118Git understands the following attributes:
 119
 120`protocol`::
 121
 122        The protocol over which the credential will be used (e.g.,
 123        `https`).
 124
 125`host`::
 126
 127        The remote hostname for a network credential.
 128
 129`path`::
 130
 131        The path with which the credential will be used. E.g., for
 132        accessing a remote https repository, this will be the
 133        repository's path on the server.
 134
 135`username`::
 136
 137        The credential's username, if we already have one (e.g., from a
 138        URL, from the user, or from a previously run helper).
 139
 140`password`::
 141
 142        The credential's password, if we are asking it to be stored.
 143
 144`url`::
 145
 146        When this special attribute is read by `git credential`, the
 147        value is parsed as a URL and treated as if its constituent parts
 148        were read (e.g., `url=https://example.com` would behave as if
 149        `protocol=https` and `host=example.com` had been provided). This
 150        can help callers avoid parsing URLs themselves.  Note that any
 151        components which are missing from the URL (e.g., there is no
 152        username in the example above) will be set to empty; if you want
 153        to provide a URL and override some attributes, provide the URL
 154        attribute first, followed by any overrides.