Added redis-cli interactive help support

updated via commands.json in redis-doc repo. Currently
use `make src/help.h` to re-generate. The following
are valid from the REPL:

  help
  help [command]
  help [group]
  help groups

ex:

  help sort
  help hash

Makefile

@@ -11,4 +11,7 @@ install: dummy
 $(TARGETS) clean:
 	cd src && $(MAKE) $@
 
+src/help.h:
+	@./utils/generate-command-help.rb > $@
+
 dummy:

src/help.h

@@ -0,0 +1,815 @@
+
+// Auto-generated, do not edit.
+
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * List command groups.
+ */
+
+#define GROUPS \
+  G(UNKNOWN, "unknown") \
+  G(SET, "set") \
+  G(LIST, "list") \
+  G(HASH, "hash") \
+  G(GENERIC, "generic") \
+  G(PUBSUB, "pubsub") \
+  G(STRING, "string") \
+  G(SERVER, "server") \
+  G(CONNECTION, "connection") \
+  G(TRANSACTIONS, "transactions") \
+  G(SORTED_SET, "sorted_set")
+
+/*
+ * Command group types.
+ */
+
+typedef enum {
+  #define G(GROUP, _) COMMAND_GROUP_##GROUP,
+  GROUPS
+  #undef G
+  COMMAND_GROUP_LENGTH
+} command_group_type_t;
+
+/*
+ * Command group type names.
+ */
+
+static char *command_group_type_names[] = {
+  #define G(_, STR) STR,
+  GROUPS
+  #undef G
+};
+
+/*
+ * Command help struct.
+ */
+
+struct command_help {
+  char *name;
+  char *params;
+  char *summary;
+  command_group_type_t group;
+  char *since;
+} command_help[] = {
+    { "APPEND"
+  , "key value"
+  , "Append a value to a key"
+  , COMMAND_GROUP_STRING
+  , "1.3.3" }
+
+  , { "AUTH"
+  , "password"
+  , "Authenticate to the server"
+  , COMMAND_GROUP_CONNECTION
+  , "0.08" }
+
+  , { "BGREWRITEAOF"
+  , "-"
+  , "Asynchronously rewrite the append-only file"
+  , COMMAND_GROUP_SERVER
+  , "1.07" }
+
+  , { "BGSAVE"
+  , "-"
+  , "Asynchronously save the dataset to disk"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "BLPOP"
+  , "(key)+ timeout"
+  , "Remove and get the first element in a list, or block until one is available"
+  , COMMAND_GROUP_LIST
+  , "1.3.1" }
+
+  , { "BRPOP"
+  , "(key)+ timeout"
+  , "Remove and get the last element in a list, or block until one is available"
+  , COMMAND_GROUP_LIST
+  , "1.3.1" }
+
+  , { "CONFIG GET"
+  , "parameter"
+  , "Get the value of a configuration parameter"
+  , COMMAND_GROUP_SERVER
+  , "2.0" }
+
+  , { "CONFIG SET"
+  , "parameter value"
+  , "Set a configuration parameter to the given value"
+  , COMMAND_GROUP_SERVER
+  , "2.0" }
+
+  , { "DBSIZE"
+  , "-"
+  , "Return the number of keys in the selected database"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "DEBUG OBJECT"
+  , "key"
+  , "Get debugging information about a key"
+  , COMMAND_GROUP_SERVER
+  , "0.101" }
+
+  , { "DEBUG SEGFAULT"
+  , "-"
+  , "Make the server crash"
+  , COMMAND_GROUP_SERVER
+  , "0.101" }
+
+  , { "DECR"
+  , "key decrement"
+  , "Decrement the integer value of a key by one"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "DECRBY"
+  , "key decrement"
+  , "Decrement the integer value of a key by the given number"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "DEL"
+  , "(key)+"
+  , "Delete a key"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "DISCARD"
+  , "-"
+  , "Discard all commands issued after MULTI"
+  , COMMAND_GROUP_TRANSACTIONS
+  , "1.3.3" }
+
+  , { "ECHO"
+  , "message"
+  , "Echo the given string"
+  , COMMAND_GROUP_CONNECTION
+  , "0.07" }
+
+  , { "EXEC"
+  , "-"
+  , "Execute all commands issued after MULTI"
+  , COMMAND_GROUP_TRANSACTIONS
+  , "1.1.95" }
+
+  , { "EXISTS"
+  , "key"
+  , "Determine if a key exists"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "EXPIRE"
+  , "key seconds"
+  , "Set a key's time to live in seconds"
+  , COMMAND_GROUP_GENERIC
+  , "0.09" }
+
+  , { "EXPIREAT"
+  , "key timestamp"
+  , "Set the expiration for a key as a UNIX timestamp"
+  , COMMAND_GROUP_GENERIC
+  , "1.1" }
+
+  , { "FLUSHALL"
+  , "-"
+  , "Remove all keys from all databases"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "FLUSHDB"
+  , "-"
+  , "Remove all keys from the current database"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "GET"
+  , "key"
+  , "Get the value of a key"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "GETSET"
+  , "key value"
+  , "Set the string value of a key and return its old value"
+  , COMMAND_GROUP_STRING
+  , "0.091" }
+
+  , { "HDEL"
+  , "key field"
+  , "Delete a hash field"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HEXISTS"
+  , "key field"
+  , "Determine if a hash field exists"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HGET"
+  , "key field"
+  , "Get the value of a hash field"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HGETALL"
+  , "key"
+  , "Get all the fields and values in a hash"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HINCRBY"
+  , "key field increment"
+  , "Increment the integer value of a hash field by the given number"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HKEYS"
+  , "key"
+  , "Get all the fields in a hash"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HLEN"
+  , "key"
+  , "Get the number of fields in a hash"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HMGET"
+  , "key (field)+"
+  , "Get the values of all the given hash fields"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HMSET"
+  , "key (field value)+"
+  , "Set multiple hash fields to multiple values"
+  , COMMAND_GROUP_HASH
+  , "1.3.8" }
+
+  , { "HSET"
+  , "key field value"
+  , "Set the string value of a hash field"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "HSETNX"
+  , "key field value"
+  , "Set the value of a hash field, only if the field does not exist"
+  , COMMAND_GROUP_HASH
+  , "1.3.8" }
+
+  , { "HVALS"
+  , "key"
+  , "Get all the values in a hash"
+  , COMMAND_GROUP_HASH
+  , "1.3.10" }
+
+  , { "INCR"
+  , "key"
+  , "Increment the integer value of a key by one"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "INCRBY"
+  , "key increment"
+  , "Increment the integer value of a key by the given number"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "INFO"
+  , "-"
+  , "Get information and statistics about the server"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "KEYS"
+  , "pattern"
+  , "Find all keys matching the given pattern"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "LASTSAVE"
+  , "-"
+  , "Get the UNIX time stamp of the last successful save to disk"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "LINDEX"
+  , "key index"
+  , "Get an element from a list by its index"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LINSERT"
+  , "key BEFORE|AFTER pivot value"
+  , "Insert an element before or after another element in a list"
+  , COMMAND_GROUP_LIST
+  , "2.1.1" }
+
+  , { "LLEN"
+  , "key"
+  , "Get the length of a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LPOP"
+  , "key"
+  , "Remove and get the first element in a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LPUSH"
+  , "key value"
+  , "Prepend a value to a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LPUSHX"
+  , "key value"
+  , "Prepend a value to a list, only if the list exists"
+  , COMMAND_GROUP_LIST
+  , "2.1.1" }
+
+  , { "LRANGE"
+  , "key start stop"
+  , "Get a range of elements from a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LREM"
+  , "key count value"
+  , "Remove elements from a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LSET"
+  , "key index value"
+  , "Set the value of an element in a list by its index"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "LTRIM"
+  , "key start stop"
+  , "Trim a list to the specified range"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "MGET"
+  , "(key)+"
+  , "Get the values of all the given keys"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "MONITOR"
+  , "-"
+  , "Listen for all requests received by the server in real time"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "MOVE"
+  , "key db"
+  , "Move a key to another database"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "MSET"
+  , "(key value)+"
+  , "Set multiple keys to multiple values"
+  , COMMAND_GROUP_STRING
+  , "1.001" }
+
+  , { "MSETNX"
+  , "(key value)+"
+  , "Set multiple keys to multiple values, only if none of the keys exist"
+  , COMMAND_GROUP_STRING
+  , "1.001" }
+
+  , { "MULTI"
+  , "-"
+  , "Mark the start of a transaction block"
+  , COMMAND_GROUP_TRANSACTIONS
+  , "1.1.95" }
+
+  , { "PERSIST"
+  , "key"
+  , "Remove the expiration from a key"
+  , COMMAND_GROUP_GENERIC
+  , "2.1.2" }
+
+  , { "PING"
+  , "-"
+  , "Ping the server"
+  , COMMAND_GROUP_CONNECTION
+  , "0.07" }
+
+  , { "PSUBSCRIBE"
+  , "pattern"
+  , "Listen for messages published to channels matching the given patterns"
+  , COMMAND_GROUP_PUBSUB
+  , "1.3.8" }
+
+  , { "PUBLISH"
+  , "channel message"
+  , "Post a message to a channel"
+  , COMMAND_GROUP_PUBSUB
+  , "1.3.8" }
+
+  , { "PUNSUBSCRIBE"
+  , "(pattern)*"
+  , "Stop listening for messages posted to channels matching the given patterns"
+  , COMMAND_GROUP_PUBSUB
+  , "1.3.8" }
+
+  , { "QUIT"
+  , "-"
+  , "Close the connection"
+  , COMMAND_GROUP_CONNECTION
+  , "0.07" }
+
+  , { "RANDOMKEY"
+  , "-"
+  , "Return a random key from the keyspace"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "RENAME"
+  , "old new"
+  , "Rename a key"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "RENAMENX"
+  , "old new"
+  , "Rename a key, only if the new key does not exist"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "RPOP"
+  , "key"
+  , "Remove and get the last element in a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "RPOPLPUSH"
+  , "source destination"
+  , "Remove the last element in a list, append it to another list and return it"
+  , COMMAND_GROUP_LIST
+  , "1.1" }
+
+  , { "RPUSH"
+  , "key value"
+  , "Append a value to a list"
+  , COMMAND_GROUP_LIST
+  , "0.07" }
+
+  , { "RPUSHX"
+  , "key value"
+  , "Append a value to a list, only if the list exists"
+  , COMMAND_GROUP_LIST
+  , "2.1.1" }
+
+  , { "SADD"
+  , "key member"
+  , "Add a member to a set"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SAVE"
+  , "-"
+  , "Synchronously save the dataset to disk"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "SCARD"
+  , "key"
+  , "Get the number of members in a set"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SDIFF"
+  , "(key)+"
+  , "Subtract multiple sets"
+  , COMMAND_GROUP_SET
+  , "0.100" }
+
+  , { "SDIFFSTORE"
+  , "destination (key)+"
+  , "Subtract multiple sets and store the resulting set in a key"
+  , COMMAND_GROUP_SET
+  , "0.100" }
+
+  , { "SELECT"
+  , "index"
+  , "Change the selected database for the current connection"
+  , COMMAND_GROUP_CONNECTION
+  , "0.07" }
+
+  , { "SET"
+  , "key value"
+  , "Set the string value of a key"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "SETEX"
+  , "key timestamp value"
+  , "Set the value and expiration of a key"
+  , COMMAND_GROUP_STRING
+  , "1.3.10" }
+
+  , { "SETNX"
+  , "key value"
+  , "Set the value of a key, only if the key does not exist"
+  , COMMAND_GROUP_STRING
+  , "0.07" }
+
+  , { "SHUTDOWN"
+  , "-"
+  , "Synchronously save the dataset to disk and then shut down the server"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "SINTER"
+  , "(key)+"
+  , "Intersect multiple sets"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SINTERSTORE"
+  , "destination (key)+"
+  , "Intersect multiple sets and store the resulting set in a key"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SISMEMBER"
+  , "key member"
+  , "Determine if a given value is a member of a set"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SLAVEOF"
+  , "host port"
+  , "Make the server a slave of another instance, or promote it as master"
+  , COMMAND_GROUP_SERVER
+  , "0.100" }
+
+  , { "SMEMBERS"
+  , "key"
+  , "Get all the members in a set"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "SMOVE"
+  , "source destination member"
+  , "Move a member from one set to another"
+  , COMMAND_GROUP_SET
+  , "0.091" }
+
+  , { "SORT"
+  , "key (BY pattern)? (LIMIT start count)? (GET pattern)* (ASC|DESC)? (ALPHA)? (STORE destination)?"
+  , "Sort the elements in a list, set or sorted set"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "SPOP"
+  , "key"
+  , "Remove and return a random member from a set"
+  , COMMAND_GROUP_SET
+  , "0.101" }
+
+  , { "SRANDMEMBER"
+  , "key"
+  , "Get a random member from a set"
+  , COMMAND_GROUP_SET
+  , "1.001" }
+
+  , { "SREM"
+  , "key member"
+  , "Remove a member from a set"
+  , COMMAND_GROUP_SET
+  , "0.07" }
+
+  , { "STRLEN"
+  , "key"
+  , "Get the length of the value stored in a key"
+  , COMMAND_GROUP_STRING
+  , "2.1.2" }
+
+  , { "SUBSCRIBE"
+  , "channel"
+  , "Listen for messages published to the given channels"
+  , COMMAND_GROUP_PUBSUB
+  , "1.3.8" }
+
+  , { "SUBSTR"
+  , "key start stop"
+  , "Get a substring of the string stored at a key"
+  , COMMAND_GROUP_STRING
+  , "1.3.4" }
+
+  , { "SUNION"
+  , "(key)+"
+  , "Add multiple sets"
+  , COMMAND_GROUP_SET
+  , "0.091" }
+
+  , { "SUNIONSTORE"
+  , "destination (key)+"
+  , "Add multiple sets and store the resulting set in a key"
+  , COMMAND_GROUP_SET
+  , "0.091" }
+
+  , { "SYNC"
+  , "-"
+  , "Internal command used for replication"
+  , COMMAND_GROUP_SERVER
+  , "0.07" }
+
+  , { "TTL"
+  , "key"
+  , "Get the time to live for a key"
+  , COMMAND_GROUP_GENERIC
+  , "0.100" }
+
+  , { "TYPE"
+  , "key"
+  , "Determine the type stored at key"
+  , COMMAND_GROUP_GENERIC
+  , "0.07" }
+
+  , { "UNSUBSCRIBE"
+  , "(channel)*"
+  , "Stop listening for messages posted to the given channels"
+  , COMMAND_GROUP_PUBSUB
+  , "1.3.8" }
+
+  , { "UNWATCH"
+  , "-"
+  , "Forget about all watched keys"
+  , COMMAND_GROUP_TRANSACTIONS
+  , "2.1.0" }
+
+  , { "WATCH"
+  , "(key)+"
+  , "Watch the given keys to determine execution of the MULTI/EXEC block"
+  , COMMAND_GROUP_TRANSACTIONS
+  , "2.1.0" }
+
+  , { "ZADD"
+  , "key score member"
+  , "Add a member to a sorted set, or update its score if it already exists"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZCARD"
+  , "key"
+  , "Get the number of members in a sorted set"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZCOUNT"
+  , "key min max"
+  , "Count the members in a sorted set with scores within the given values"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.3" }
+
+  , { "ZINCRBY"
+  , "key increment member"
+  , "Increment the score of a member in a sorted set"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZINTERSTORE"
+  , "destination (key)+ (WEIGHTS weight)? (AGGREGATE SUM|MIN|MAX)?"
+  , "Intersect multiple sorted sets and store the resulting sorted set in a new key"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.10" }
+
+  , { "ZRANGE"
+  , "key start stop"
+  , "Return a range of members in a sorted set, by index"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZRANGEBYSCORE"
+  , "key min max"
+  , "Return a range of members in a sorted set, by score"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.050" }
+
+  , { "ZRANK"
+  , "key member"
+  , "Determine the index of a member in a sorted set"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.4" }
+
+  , { "ZREM"
+  , "key member"
+  , "Remove a member from a sorted set"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZREMRANGEBYRANK"
+  , "key start stop"
+  , "Remove all members in a sorted set within the given indexes"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.4" }
+
+  , { "ZREMRANGEBYSCORE"
+  , "key min max"
+  , "Remove all members in a sorted set within the given scores"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZREVRANGE"
+  , "key start stop"
+  , "Return a range of members in a sorted set, by index, with scores ordered from high to low"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZREVRANK"
+  , "key member"
+  , "Determine the index of a member in a sorted set, with scores ordered from high to low"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.4" }
+
+  , { "ZSCORE"
+  , "key member"
+  , "Get the score associated with the given member in a sorted set"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.1" }
+
+  , { "ZUNIONSTORE"
+  , "destination (key)+ (WEIGHTS weight)? (AGGREGATE SUM|MIN|MAX)?"
+  , "Add multiple sorted sets and store the resulting sorted set in a new key"
+  , COMMAND_GROUP_SORTED_SET
+  , "1.3.10" }
+};
+
+/*
+ * Output command help to stdout.
+ */
+
+static void
+output_command_help(struct command_help *help) {
+  printf("\n  \x1b[1m%s\x1b[0m \x1b[90m%s\x1b[0m\n", help->name, help->params);
+  printf("  \x1b[33msummary:\x1b[0m %s\n", help->summary);
+  printf("  \x1b[33msince:\x1b[0m %s\n", help->since);
+  printf("  \x1b[33mgroup:\x1b[0m %s\n", command_group_type_names[help->group]);
+}
+
+/*
+ * Return command group type by name string.
+ */
+
+static command_group_type_t
+command_group_type_by_name(const char *name) {
+  for (int i = 0; i < COMMAND_GROUP_LENGTH; ++i) {
+    const char *group = command_group_type_names[i];
+    if (0 == strcasecmp(name, group)) return i;
+  }
+  return 0;
+}
+
+/*
+ * Output group names.
+ */
+
+static void
+output_group_help() {
+	for (int i = 0; i < COMMAND_GROUP_LENGTH; ++i) {
+		if (COMMAND_GROUP_UNKNOWN == i) continue;
+		const char *group = command_group_type_names[i];
+		printf("  \x1b[90m-\x1b[0m %s\n", group);
+	}
+}
+
+/*
+ * Output all command help, filtering by group or command name.
+ */
+
+static void
+output_help(int argc, const char **argv) {
+  int len = sizeof(command_help) / sizeof(struct command_help);
+
+	if (argc && 0 == strcasecmp("groups", argv[0])) {
+		output_group_help();
+		return;
+	}
+
+	command_group_type_t group = argc
+    ? command_group_type_by_name(argv[0])
+    : COMMAND_GROUP_UNKNOWN;
+
+  for (int i = 0; i < len; ++i) {
+    struct command_help help = command_help[i];
+    if (argc && !group && 0 != strcasecmp(help.name, argv[0])) continue;
+    if (group && group != help.group) continue;
+    output_command_help(&help);
+  }
+  puts("");
+}

src/redis-cli.c

@@ -44,6 +44,7 @@
 #include "adlist.h"
 #include "zmalloc.h"
 #include "linenoise.h"
+#include "help.h"
 
 #define REDIS_NOTUSED(V) ((void) V)
 
@@ -248,22 +249,6 @@ static int selectDb(int fd) {
     return 0;
 }
 
-static void showInteractiveHelp(void) {
-    printf(
-    "\n"
-    "Welcome to redis-cli " REDIS_VERSION "!\n"
-    "Just type any valid Redis command to see a pretty printed output.\n"
-    "\n"
-    "It is possible to quote strings, like in:\n"
-    "  set \"my key\" \"some string \\xff\\n\"\n"
-    "\n"
-    "You can find a list of valid Redis commands at\n"
-    "  http://code.google.com/p/redis/wiki/CommandReference\n"
-    "\n"
-    "Note: redis-cli supports line editing, use up/down arrows for history."
-    "\n\n");
-}
-
 static int cliSendCommand(int argc, char **argv, int repeat) {
     char *command = argv[0];
     int fd, j, retval = 0;
@@ -271,7 +256,7 @@ static int cliSendCommand(int argc, char **argv, int repeat) {
 
     config.raw_output = !strcasecmp(command,"info");
     if (!strcasecmp(command,"help")) {
-        showInteractiveHelp();
+        output_help(--argc, ++argv);
         return 0;
     }
     if (!strcasecmp(command,"shutdown")) config.shutdown = 1;

utils/generate-command-help.rb

@@ -0,0 +1,56 @@
+#!/usr/bin/env ruby
+
+require 'net/http'
+require 'net/https'
+require 'json'
+require 'uri'
+
+dest = ARGV[0]
+tmpl = File.read './utils/help.h'
+
+url = URI.parse 'https://github.com/antirez/redis-doc/raw/master/commands.json'
+client = Net::HTTP.new url.host, url.port
+client.use_ssl = true
+res = client.get url.path
+
+def argument arg
+  name = arg['name'].is_a?(Array) ? arg['name'].join(' ') : arg['name']
+  name = arg['enum'].join '|' if 'enum' == arg['type']
+  name = arg['command'] + ' ' + name if arg['command']
+  if arg['multiple']
+    name = "(#{name})"
+    name += arg['optional'] ? '*' : '+'
+  elsif arg['optional']
+    name = "(#{name})?"
+  end
+  name
+end
+
+def arguments command
+  return '-' unless command['arguments']
+  command['arguments'].map do |arg|
+    argument arg
+  end.join ' '
+end
+
+case res
+when Net::HTTPSuccess
+  first = true
+  commands = JSON.parse(res.body)
+  c = commands.map do |key, command|
+    buf = if first
+      first = false
+      ' '
+    else
+      "\n  ,"
+    end
+    buf += " { \"#{key}\"\n" +
+    "  , \"#{arguments(command)}\"\n" +
+    "  , \"#{command['summary']}\"\n" +
+    "  , COMMAND_GROUP_#{command['group'].upcase}\n" +
+    "  , \"#{command['since']}\" }"
+  end.join("\n")
+  puts "\n// Auto-generated, do not edit.\n" + tmpl.sub('__COMMANDS__', c)
+else
+  res.error!
+end

utils/help.h

@@ -0,0 +1,119 @@
+
+#include <stdio.h>
+#include <string.h>
+
+/*
+ * List command groups.
+ */
+
+#define GROUPS \
+  G(UNKNOWN, "unknown") \
+  G(SET, "set") \
+  G(LIST, "list") \
+  G(HASH, "hash") \
+  G(GENERIC, "generic") \
+  G(PUBSUB, "pubsub") \
+  G(STRING, "string") \
+  G(SERVER, "server") \
+  G(CONNECTION, "connection") \
+  G(TRANSACTIONS, "transactions") \
+  G(SORTED_SET, "sorted_set")
+
+/*
+ * Command group types.
+ */
+
+typedef enum {
+  #define G(GROUP, _) COMMAND_GROUP_##GROUP,
+  GROUPS
+  #undef G
+  COMMAND_GROUP_LENGTH
+} command_group_type_t;
+
+/*
+ * Command group type names.
+ */
+
+static char *command_group_type_names[] = {
+  #define G(_, STR) STR,
+  GROUPS
+  #undef G
+};
+
+/*
+ * Command help struct.
+ */
+
+struct command_help {
+  char *name;
+  char *params;
+  char *summary;
+  command_group_type_t group;
+  char *since;
+} command_help[] = {
+  __COMMANDS__
+};
+
+/*
+ * Output command help to stdout.
+ */
+
+static void
+output_command_help(struct command_help *help) {
+  printf("\n  \x1b[1m%s\x1b[0m \x1b[90m%s\x1b[0m\n", help->name, help->params);
+  printf("  \x1b[33msummary:\x1b[0m %s\n", help->summary);
+  printf("  \x1b[33msince:\x1b[0m %s\n", help->since);
+  printf("  \x1b[33mgroup:\x1b[0m %s\n", command_group_type_names[help->group]);
+}
+
+/*
+ * Return command group type by name string.
+ */
+
+static command_group_type_t
+command_group_type_by_name(const char *name) {
+  for (int i = 0; i < COMMAND_GROUP_LENGTH; ++i) {
+    const char *group = command_group_type_names[i];
+    if (0 == strcasecmp(name, group)) return i;
+  }
+  return 0;
+}
+
+/*
+ * Output group names.
+ */
+
+static void
+output_group_help() {
+	for (int i = 0; i < COMMAND_GROUP_LENGTH; ++i) {
+		if (COMMAND_GROUP_UNKNOWN == i) continue;
+		const char *group = command_group_type_names[i];
+		printf("  \x1b[90m-\x1b[0m %s\n", group);
+	}
+}
+
+/*
+ * Output all command help, filtering by group or command name.
+ */
+
+static void
+output_help(int argc, const char **argv) {
+  int len = sizeof(command_help) / sizeof(struct command_help);
+
+	if (argc && 0 == strcasecmp("groups", argv[0])) {
+		output_group_help();
+		return;
+	}
+
+	command_group_type_t group = argc
+    ? command_group_type_by_name(argv[0])
+    : COMMAND_GROUP_UNKNOWN;
+
+  for (int i = 0; i < len; ++i) {
+    struct command_help help = command_help[i];
+    if (argc && !group && 0 != strcasecmp(help.name, argv[0])) continue;
+    if (group && group != help.group) continue;
+    output_command_help(&help);
+  }
+  puts("");
+}