config API
==========
-The config API gives callers a way to access git configuration files
+The config API gives callers a way to access Git configuration files
(and files which have the same syntax). See linkgit:git-config[1] for a
discussion of the config file syntax.
caller-provided callback function. The callback function is responsible
for any actions to be taken on the config option, and is free to ignore
some options. It is not uncommon for the configuration to be parsed
-several times during the run of a git program, with different callbacks
+several times during the run of a Git program, with different callbacks
picking out different variables useful to themselves.
A config callback function takes three parameters:
---------------------
Most programs will simply want to look up variables in all config files
-that git knows about, using the normal precedence rules. To do this,
+that Git knows about, using the normal precedence rules. To do this,
call `git_config` with a callback function and void data pointer.
`git_config` will read all config sources in order of increasing
The `git_config_with_options` function lets the caller examine config
while adjusting some of the default behavior of `git_config`. It should
-almost never be used by "regular" git code that is looking up
+almost never be used by "regular" Git code that is looking up
configuration variables. It is intended for advanced callers like
`git-config`, which are intentionally tweaking the normal config-lookup
process. It takes two extra parameters:
There is a special version of `git_config` called `git_config_early`.
This version takes an additional parameter to specify the repository
config, instead of having it looked up via `git_path`. This is useful
-early in a git program before the repository has been found. Unless
+early in a Git program before the repository has been found. Unless
you're working with early setup code, you probably don't want to use
this.
Writing Config Files
--------------------
-TODO
+Git gives multiple entry points in the Config API to write config values to
+files namely `git_config_set_in_file` and `git_config_set`, which write to
+a specific config file or to `.git/config` respectively. They both take a
+key/value pair as parameter.
+In the end they both call `git_config_set_multivar_in_file` which takes four
+parameters:
+
+- the name of the file, as a string, to which key/value pairs will be written.
+
+- the name of key, as a string. This is in canonical "flat" form: the section,
+ subsection, and variable segments will be separated by dots, and the section
+ and variable segments will be all lowercase.
+ E.g., `core.ignorecase`, `diff.SomeType.textconv`.
+
+- the value of the variable, as a string. If value is equal to NULL, it will
+ remove the matching key from the config file.
+
+- the value regex, as a string. It will disregard key/value pairs where value
+ does not match.
+
+- a multi_replace value, as an int. If value is equal to zero, nothing or only
+ one matching key/value is replaced, else all matching key/values (regardless
+ how many) are removed, before the new pair is written.
+
+It returns 0 on success.
+
+Also, there are functions `git_config_rename_section` and
+`git_config_rename_section_in_file` with parameters `old_name` and `new_name`
+for renaming or removing sections in the config files. If NULL is passed
+through `new_name` parameter, the section will be removed from the config file.