Add an option to specify a file to config builtin

There are (really!) systems where using environment variables is very
cumbersome (yes, Windows, it has problems unsetting them). Besides this
form is shorter.

Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-config.txt

@@ -9,17 +9,17 @@ git-config - Get and set repository or global options
 SYNOPSIS
 --------
 [verse]
-'git-config' [--system | --global] [type] [-z|--null] name [value [value_regex]]
-'git-config' [--system | --global] [type] --add name value
-'git-config' [--system | --global] [type] --replace-all name [value [value_regex]]
-'git-config' [--system | --global] [type] [-z|--null] --get name [value_regex]
-'git-config' [--system | --global] [type] [-z|--null] --get-all name [value_regex]
-'git-config' [--system | --global] [type] [-z|--null] --get-regexp name_regex [value_regex]
-'git-config' [--system | --global] --unset name [value_regex]
-'git-config' [--system | --global] --unset-all name [value_regex]
-'git-config' [--system | --global] --rename-section old_name new_name
-'git-config' [--system | --global] --remove-section name
-'git-config' [--system | --global] [-z|--null] -l | --list
+'git-config' [--system | --global | [-f|--file] config-file] [type] [-z|--null] name [value [value_regex]]
+'git-config' [--system | --global | [-f|--file] config-file] [type] --add name value
+'git-config' [--system | --global | [-f|--file] config-file] [type] --replace-all name [value [value_regex]]
+'git-config' [--system | --global | [-f|--file] config-file] [type] [-z|--null] --get name [value_regex]
+'git-config' [--system | --global | [-f|--file] config-file] [type] [-z|--null] --get-all name [value_regex]
+'git-config' [--system | --global | [-f|--file] config-file] [type] [-z|--null] --get-regexp name_regex [value_regex]
+'git-config' [--system | --global | [-f|--file] config-file] --unset name [value_regex]
+'git-config' [--system | --global | [-f|--file] config-file] --unset-all name [value_regex]
+'git-config' [--system | --global | [-f|--file] config-file] --rename-section old_name new_name
+'git-config' [--system | --global | [-f|--file] config-file] --remove-section name
+'git-config' [--system | --global | [-f|--file] config-file] [-z|--null] -l | --list
 
 DESCRIPTION
 -----------
@@ -42,8 +42,8 @@ no checks or transformations are performed on the value.
 
 This command will fail if:
 
-. The .git/config file is invalid,
-. Can not write to .git/config,
+. The config file is invalid,
+. Can not write to the config file,
 . no section was provided,
 . the section or key is invalid,
 . you try to unset an option which does not exist,
@@ -93,6 +93,9 @@ rather than from all available files.
 +
 See also <<FILES>>.
 
+-f config-file, --file config-file::
+	Use the given config file instead of the one specified by GIT_CONFIG.
+
 --remove-section::
 	Remove the given section from the configuration file.
 

builtin-config.c

@@ -2,7 +2,7 @@
 #include "cache.h"
 
 static const char git_config_set_usage[] =
-"git-config [ --global | --system ] [ --bool | --int ] [ -z | --null ] [--get | --get-all | --get-regexp | --replace-all | --add | --unset | --unset-all] name [value [value_regex]] | --rename-section old_name new_name | --remove-section name | --list";
+"git-config [ --global | --system | [ -f | --file ] config-file ] [ --bool | --int ] [ -z | --null ] [--get | --get-all | --get-regexp | --replace-all | --add | --unset | --unset-all] name [value [value_regex]] | --rename-section old_name new_name | --remove-section name | --list";
 
 static char *key;
 static regex_t *key_regexp;
@@ -186,6 +186,13 @@ int cmd_config(int argc, const char **argv, const char *prefix)
 		}
 		else if (!strcmp(argv[1], "--system"))
 			setenv(CONFIG_ENVIRONMENT, ETC_GITCONFIG, 1);
+		else if (!strcmp(argv[1], "--file") || !strcmp(argv[1], "-f")) {
+			if (argc < 3)
+				usage(git_config_set_usage);
+			setenv(CONFIG_ENVIRONMENT, argv[2], 1);
+			argc--;
+			argv++;
+		}
 		else if (!strcmp(argv[1], "--null") || !strcmp(argv[1], "-z")) {
 			term = '\0';
 			delim = '\n';