lib: de-conflict log-filter CLI command

`log-filter WORD` was giving me a serious headache since it also matches
`log WORD` due to the way the CLI token handling works.  This meant that
a mistyped `log something` command would silently be interpreted as a
filter string, causing me serious headscratching and WTFs until I
figured what was going on.

Remove this UX pitfall so noone else falls into it.  (Since the command
was never saved to config, renaming it shouldn't cause trouble.)

[Also I apparently forgot to update the docs when I transferred this
over to the new zlog bits...]

TODO for a rainy day:  since we collect all the CLI commands anyway, we
should warn somewhere for "2nd level ambiguous" commands like this.

Signed-off-by: David Lamparter <equinox@diac24.net>

doc/user/basic.rst

@@ -174,11 +174,17 @@ Basic Config Commands
    is used to start the daemon then this command is turned on by default
    and cannot be turned off and the [no] form of the command is dissallowed.
 
-.. clicmd:: log-filter WORD [DAEMON]
+.. clicmd:: log filtered-file [FILENAME [LEVEL]]
+
+   Configure a destination file for filtered logs with the
+   :clicmd:`log filter-text WORD` command.
+
+.. clicmd:: log filter-text WORD
 
    This command forces logs to be filtered on a specific string. A log message
    will only be printed if it matches on one of the filters in the log-filter
-   table. Can be daemon independent.
+   table.  The filter only applies to file logging targets configured with
+   :clicmd:`log filtered-file [FILENAME [LEVEL]]`.
 
    .. note::
 
@@ -187,10 +193,15 @@ Basic Config Commands
       Log filters prevent this but you should still expect a small performance
       hit due to filtering each of all those logs.
 
-.. clicmd:: log-filter clear [DAEMON]
+   .. note::
+
+      This setting is not saved to ``frr.conf`` and not shown in
+      :clicmd:`show running-config`.  It is intended for ephemeral debugging
+      purposes only.
+
+.. clicmd:: clear log filter-text
 
-   This command clears all current filters in the log-filter table. Can be
-   daemon independent.
+   This command clears all current filters in the log-filter table.
 
 
 .. clicmd:: log immediate-mode

lib/log_vty.c

@@ -588,8 +588,9 @@ DEFUN (no_config_log_filterfile,
 
 DEFPY (log_filter,
        log_filter_cmd,
-       "[no] log-filter WORD$filter",
+       "[no] log filter-text WORD$filter",
        NO_STR
+       "Logging control\n"
        FILTER_LOG_STR
        "String to filter by\n")
 {
@@ -616,8 +617,9 @@ DEFPY (log_filter,
 /* Clear all log filters */
 DEFPY (log_filter_clear,
        log_filter_clear_cmd,
-       "clear log-filter",
+       "clear log filter-text",
        CLEAR_STR
+       "Logging control\n"
        FILTER_LOG_STR)
 {
 	zlog_filter_clear();
@@ -627,8 +629,9 @@ DEFPY (log_filter_clear,
 /* Show log filter */
 DEFPY (show_log_filter,
        show_log_filter_cmd,
-       "show log-filter",
+       "show logging filter-text",
        SHOW_STR
+       "Show current logging configuration\n"
        FILTER_LOG_STR)
 {
 	char log_filters[ZLOG_FILTERS_MAX * (ZLOG_FILTER_LENGTH_MAX + 3)] = "";