diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index bb2348d12..542b77543 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -20,6 +20,7 @@ https://weechat.org/files/releasenotes/ReleaseNotes-devel.html[release notes]
 
 New features::
 
+  * core: display similar command names when a command is unknown (issue #1877)
   * core: force ctrl keys to lower case when they are added (issue #1875)
   * core, plugins: make many identifiers case sensitive (issue #1872, issue #398, bug #32213)
   * alias: use lower case for default aliases (issue #1872)
diff --git a/po/cs.po b/po/cs.po
index eb70e0341..d7b5fb5c5 100644
--- a/po/cs.po
+++ b/po/cs.po
@@ -21,7 +21,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Ondřej Súkup <mimi.vx@gmail.com>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -147,6 +147,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sChyba: příkaz \"%s\" již existuje pro plugin \"%s\""
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sChyba: neznámý příkaz \"%s\" (napište /help pro nápovědu)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr ""
@@ -4472,10 +4478,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sChyba: neznámý příkaz \"%s\" (napište /help pro nápovědu)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/de.po b/po/de.po
index d6d21f9ff..196c18459 100644
--- a/po/de.po
+++ b/po/de.po
@@ -26,7 +26,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2023-01-29 13:05+0100\n"
 "Last-Translator: Nils Görs <weechatter@arcor.de>\n"
 "Language-Team: German - Germany <weechatter@arcor.de>\n"
@@ -147,6 +147,13 @@ msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr ""
 "%sEin anderer Befehl \"%s\" existiert bereits für die Erweiterung \"%s\""
 
+#, fuzzy, c-format
+#| msgid "%sUnknown command \"%s\" (type /help for help)"
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sDer Befehl \"%s\" ist nicht bekannt (für eine Hilfe nutze /help)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sBad file descriptor (%d) wurde in Funktion \"hook_fd\" genutzt"
@@ -5620,10 +5627,6 @@ msgstr ""
 "Warnung: momentan ist der Befehl \"%s\" nicht ausführbar (Befehl: \"%s\", "
 "Buffer: \"%s\")"
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sDer Befehl \"%s\" ist nicht bekannt (für eine Hilfe nutze /help)"
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/es.po b/po/es.po
index caca04124..d27dda2d6 100644
--- a/po/es.po
+++ b/po/es.po
@@ -22,7 +22,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Santiago Forero <santiago@forero.xyz>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -145,6 +145,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sError: el comando \"%s\" ya existe en el plugin \"%s\""
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sError: comando \"%s\" desconocido (use /help para ver la ayuda)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sError: mal descriptor de archivo (%d) usado en hook_fd"
@@ -5030,10 +5036,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sError: comando \"%s\" desconocido (use /help para ver la ayuda)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/fr.po b/po/fr.po
index 348cbc477..50480ce25 100644
--- a/po/fr.po
+++ b/po/fr.po
@@ -21,8 +21,8 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
-"PO-Revision-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
+"PO-Revision-Date: 2023-01-30 21:32+0100\n"
 "Last-Translator: Sébastien Helleu <flashcode@flashtux.org>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
 "Language: fr\n"
@@ -139,6 +139,14 @@ msgstr "Fichier"
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sUne autre commande \"%s\" existe déjà pour l'extension \"%s\""
 
+#, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr ""
+"%sCommande \"%s\" inconnue (tapez /help pour l'aide), commandes avec un nom "
+"similaire : %s"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sMauvais descripteur de fichier (%d) utilisé dans hook_fd"
@@ -5486,10 +5494,6 @@ msgstr ""
 "attention : la commande \"%s\" n'est pas autorisée actuellement (commande : "
 "\"%s\", tampon : \"%s\")"
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sCommande \"%s\" inconnue (tapez /help pour l'aide)"
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/hu.po b/po/hu.po
index 9d86d8902..a7cb0f87e 100644
--- a/po/hu.po
+++ b/po/hu.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Andras Voroskoi <voroskoi@frugalware.org>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -147,6 +147,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%s az ignore már létezik\n"
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%s a \"%s\" aliasz vagy parancs nem található\n"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr ""
@@ -4052,10 +4058,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%s a \"%s\" aliasz vagy parancs nem található\n"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/it.po b/po/it.po
index 0e66e2e66..3d9979ded 100644
--- a/po/it.po
+++ b/po/it.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Esteban I. Ruiz Moreno <exio4.com@gmail.com>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -144,6 +144,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sErrore: un altro comando \"%s\" esiste già per il plugin \"%s\""
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sErrore: comando \"%s\" sconosciuto (digita /help per l'aiuto)"
+
 #, fuzzy, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sErrore: descrittore file errato (%d) usato in hook_fd"
@@ -4729,10 +4735,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sErrore: comando \"%s\" sconosciuto (digita /help per l'aiuto)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/ja.po b/po/ja.po
index d0263810a..f5eed819a 100644
--- a/po/ja.po
+++ b/po/ja.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: AYANOKOUZI, Ryuunosuke <i38w7i3@yahoo.co.jp>\n"
 "Language-Team: Japanese <https://github.com/l/weechat/tree/master/"
@@ -145,6 +145,12 @@ msgstr ""
 "%1$sエラー: プラグイン \"%3$s\" で他のコマンド \"%2$s\" は既に定義されていま"
 "す"
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sエラー: 未定義のコマンド \"%s\" (ヘルプを見るには /help を入力)"
+
 #, fuzzy, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sエラー: hook_fd で不正なファイルディスクリプタ (%d) が使われました"
@@ -5259,10 +5265,6 @@ msgstr ""
 "警告: コマンド \"%s\" は許可されていません (コマンド: \"%s\"、バッファ: "
 "\"%s\")"
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sエラー: 未定義のコマンド \"%s\" (ヘルプを見るには /help を入力)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/pl.po b/po/pl.po
index 4e78cff40..2ea6787c0 100644
--- a/po/pl.po
+++ b/po/pl.po
@@ -22,7 +22,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-12-30 14:10+0100\n"
 "Last-Translator: Krzysztof Korościk <soltys@soltys.info>\n"
 "Language-Team: Polish <kde-i18n-doc@kde.org>\n"
@@ -141,6 +141,13 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sIstnieje już inna komenda \"%s\" dla wtyczki \"%s\""
 
+#, fuzzy, c-format
+#| msgid "%sUnknown command \"%s\" (type /help for help)"
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sNieznana komenda \"%s\" (wpisz /help , aby uzyskać pomoc)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sZły deskryptor pliku (%d) użyty w hook_fd"
@@ -5423,10 +5430,6 @@ msgstr ""
 "uwaga: komenda \"%s\" nie jest obecnie dozwolona (komenda: \"%s\", bufor: "
 "\"%s\")"
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sNieznana komenda \"%s\" (wpisz /help , aby uzyskać pomoc)"
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/pt.po b/po/pt.po
index 4e380c45d..cd3c556bc 100644
--- a/po/pt.po
+++ b/po/pt.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Vasco Almeida <vascomalmeida@sapo.pt>\n"
 "Language-Team: Portuguese <>\n"
@@ -146,6 +146,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sErro: outro comando \"%s\" já existe para o plugin \"%s\""
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sErro: comando desconhecido: \"%s\" (escreva /help para obter ajuda)"
+
 #, fuzzy, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sErro: descritor de ficheiro incorreto (%d) usado em hook_fd"
@@ -5289,10 +5295,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sErro: comando desconhecido: \"%s\" (escreva /help para obter ajuda)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/pt_BR.po b/po/pt_BR.po
index 2d4fcf42e..4f3f8da3e 100644
--- a/po/pt_BR.po
+++ b/po/pt_BR.po
@@ -21,7 +21,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Érico Nogueira <ericonr@disroot.org>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -143,6 +143,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sOutro comando \"%s\" já existe para o plugin \"%s\""
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sErro com o comando \"%s\" (ajuda no comando: /help %s)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sDescritor de arquivo ruim (%d) usado em hook_fd"
@@ -4721,10 +4727,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sErro com o comando \"%s\" (ajuda no comando: /help %s)"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/ru.po b/po/ru.po
index e65ab0060..bad808969 100644
--- a/po/ru.po
+++ b/po/ru.po
@@ -21,7 +21,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Aleksey V Zapparov AKA ixti <ixti@member.fsf.org>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -155,6 +155,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%s игнорирование уже существует\n"
 
+#, fuzzy, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%s сокращение или команда \"%s\" не найдены\n"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr ""
@@ -4080,10 +4086,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, fuzzy, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%s сокращение или команда \"%s\" не найдены\n"
-
 #, fuzzy, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/sr.po b/po/sr.po
index dc0518311..e7373fdab 100644
--- a/po/sr.po
+++ b/po/sr.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-12-05 09:44+0400\n"
 "Last-Translator: Ivan Pešić <ivan.pesic@gmail.com>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -144,6 +144,13 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sВећ постоји друга команда \"%s\" за додатак \"%s\""
 
+#, fuzzy, c-format
+#| msgid "%sUnknown command \"%s\" (type /help for help)"
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%sНепозната команда „%s” (за помоћ откуцајте /help)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sУ hook_fd је употребљен лош дескриптор фајла (%d)"
@@ -5603,10 +5610,6 @@ msgid ""
 msgstr ""
 "упозорење: тренутно се не дозвољава команда „%s” (команда: „%s”, бафер: „%s”)"
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%sНепозната команда „%s” (за помоћ откуцајте /help)"
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/tr.po b/po/tr.po
index 2b495e1fd..97456fe95 100644
--- a/po/tr.po
+++ b/po/tr.po
@@ -20,7 +20,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2022-10-15 22:51+0200\n"
 "Last-Translator: Emir SARI <emir_sari@icloud.com>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -143,6 +143,13 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr "%sŞu eklenti için başka bir komut (\"%s\") halihazırda var: \"%s\""
 
+#, fuzzy, c-format
+#| msgid "%sUnknown command \"%s\" (type /help for help)"
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr "%s Bilinmeyen komut \"%s\" (yardım için /help yazın)"
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr "%sHatalı dosya açıklayıcısı (%d) hook_fd içinde kullanılmış"
@@ -5674,10 +5681,6 @@ msgstr ""
 "uyarı: şu anda \"%s\" komutuna izin verilmiyor (komut: \"%s\", arabellek: "
 "\"%s\")"
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr "%s Bilinmeyen komut \"%s\" (yardım için /help yazın)"
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/po/weechat.pot b/po/weechat.pot
index 4bbb97bfd..a90ee12a8 100644
--- a/po/weechat.pot
+++ b/po/weechat.pot
@@ -21,7 +21,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: WeeChat\n"
 "Report-Msgid-Bugs-To: flashcode@flashtux.org\n"
-"POT-Creation-Date: 2023-01-29 16:50+0100\n"
+"POT-Creation-Date: 2023-01-30 21:30+0100\n"
 "PO-Revision-Date: 2014-08-16 10:27+0200\n"
 "Last-Translator: Sébastien Helleu <flashcode@flashtux.org>\n"
 "Language-Team: weechat-dev <weechat-dev@nongnu.org>\n"
@@ -131,6 +131,12 @@ msgstr ""
 msgid "%sAnother command \"%s\" already exists for plugin \"%s\""
 msgstr ""
 
+#, c-format
+msgid ""
+"%sUnknown command \"%s\" (type /help for help), commands with similar name: "
+"%s"
+msgstr ""
+
 #, c-format
 msgid "%sBad file descriptor (%d) used in hook_fd"
 msgstr ""
@@ -3696,10 +3702,6 @@ msgid ""
 "buffer: \"%s\")"
 msgstr ""
 
-#, c-format
-msgid "%sUnknown command \"%s\" (type /help for help)"
-msgstr ""
-
 #, c-format
 msgid ""
 "%sAmbiguous command \"%s\": it exists in many plugins and not in \"%s\" "
diff --git a/src/core/hook/wee-hook-command.c b/src/core/hook/wee-hook-command.c
index 435b0d702..641b345a1 100644
--- a/src/core/hook/wee-hook-command.c
+++ b/src/core/hook/wee-hook-command.c
@@ -27,6 +27,7 @@
 #include <string.h>
 
 #include "../weechat.h"
+#include "../wee-arraylist.h"
 #include "../wee-config.h"
 #include "../wee-hook.h"
 #include "../wee-infolist.h"
@@ -35,6 +36,7 @@
 #include "../wee-string.h"
 #include "../wee-utf8.h"
 #include "../../gui/gui-chat.h"
+#include "../../gui/gui-filter.h"
 #include "../../plugins/plugin.h"
 
 
@@ -522,6 +524,203 @@ hook_command_exec (struct t_gui_buffer *buffer, int any_plugin,
     return rc;
 }
 
+/*
+ * Gets relevance for cmd2 (existing command) compared to cmd1 (non-existing
+ * command).
+ *
+ * Both commands are in lower case.
+ *
+ * Returns a number based on the Levenshtein distance between two commands,
+ * lower is better.
+ */
+
+int
+hook_command_similar_get_relevance (const char *cmd1, int length_cmd1,
+                                    const char *cmd2, int length_cmd2)
+{
+    const char *pos;
+    int relevance, factor;
+
+    /* perfect match if commands are the same (different case) */
+    if (strcmp (cmd1, cmd2) == 0)
+        return -1;
+
+    /* init relevance with Levenshtein distance (lower is better) */
+    relevance = string_levenshtein (cmd1, cmd2, 1);
+
+    /* bonus if one command includes the other */
+    pos = (length_cmd1 < length_cmd2) ?
+        strstr (cmd2, cmd1) : strstr (cmd1, cmd2);
+    if (pos)
+    {
+        factor = 4;
+        /* extra bonus if match is at beginning */
+        if ((pos == cmd1) || (pos == cmd2))
+            factor = 5;
+        relevance /= factor;
+    }
+    else
+    {
+        /* malus if no chars in common between two words */
+        if (string_get_common_bytes_count (cmd1, cmd2) == 0)
+            relevance *= 2;
+    }
+
+    return relevance;
+}
+
+/*
+ * Compares similar commands to sort them by relevance (lower number first:
+ * best relevance).
+ */
+
+int
+hook_command_similar_cmp_cb (void *data, struct t_arraylist *arraylist,
+                             void *pointer1, void *pointer2)
+{
+    struct t_hook_command_similar *ptr_cmd1, *ptr_cmd2;
+
+    /* make C compiler happy */
+    (void) data;
+    (void) arraylist;
+
+    ptr_cmd1 = (struct t_hook_command_similar *)pointer1;
+    ptr_cmd2 = (struct t_hook_command_similar *)pointer2;
+
+    if (ptr_cmd1->relevance < ptr_cmd2->relevance)
+        return -1;
+
+    if (ptr_cmd1->relevance > ptr_cmd2->relevance)
+        return 1;
+
+    return string_strcasecmp (ptr_cmd1->command, ptr_cmd2->command);
+}
+
+/*
+ * Frees a similar command.
+ */
+
+void
+hook_command_similar_free_cb (void *data, struct t_arraylist *arraylist,
+                              void *pointer)
+{
+    /* make C compiler happy */
+    (void) data;
+    (void) arraylist;
+
+    free (pointer);
+}
+
+/*
+ * Builds an arraylist with similar commands.
+ *
+ * Note: result must be freed after use.
+ */
+
+struct t_arraylist *
+hook_command_build_list_similar_commands (const char *command)
+{
+    struct t_arraylist *list_commands;
+    struct t_hook *ptr_hook;
+    struct t_hook_command_similar *cmd_similar;
+    char *cmd1, *cmd2;
+    int length_cmd1, length_cmd2, relevance;
+
+    cmd1 = string_tolower (command);
+    if (!cmd1)
+        return NULL;
+
+    length_cmd1 = strlen (cmd1);
+
+    list_commands = arraylist_new (64, 1, 0,
+                                   &hook_command_similar_cmp_cb, NULL,
+                                   &hook_command_similar_free_cb, NULL);
+
+    for (ptr_hook = weechat_hooks[HOOK_TYPE_COMMAND]; ptr_hook;
+         ptr_hook = ptr_hook->next_hook)
+    {
+        if (ptr_hook->deleted)
+            continue;
+        cmd2 = string_tolower (HOOK_COMMAND(ptr_hook, command));
+        if (!cmd2)
+            continue;
+        length_cmd2 = strlen (cmd2);
+        relevance = hook_command_similar_get_relevance (cmd1, length_cmd1,
+                                                        cmd2, length_cmd2);
+        cmd_similar = (struct t_hook_command_similar *)malloc (
+            sizeof (*cmd_similar));
+        if (cmd_similar)
+        {
+            cmd_similar->command = HOOK_COMMAND(ptr_hook, command);
+            cmd_similar->relevance = relevance;
+        }
+        arraylist_add (list_commands, cmd_similar);
+        free (cmd2);
+    }
+
+    free (cmd1);
+
+    return list_commands;
+}
+
+/*
+ * Displays similar command when an unknown command has been used, to help
+ * the user.
+ */
+
+void
+hook_command_display_error_unknown (const char *command)
+{
+    struct t_arraylist *list_commands;
+    struct t_hook_command_similar *cmd_similar;
+    char **str_commands;
+    int i, list_size, found;
+
+    if (!command || !command[0])
+        return;
+
+    list_commands = hook_command_build_list_similar_commands (command);
+    if (!list_commands)
+        return;
+
+    str_commands = string_dyn_alloc (256);
+    if (!str_commands)
+    {
+        arraylist_free (list_commands);
+        return;
+    }
+
+    found = 0;
+    list_size = arraylist_size (list_commands);
+    for (i = 0; i < list_size; i++)
+    {
+        cmd_similar = (struct t_hook_command_similar *)arraylist_get (
+            list_commands, i);
+        if (cmd_similar->relevance >= 3)
+            break;
+        if (found > 0)
+            string_dyn_concat (str_commands, ", ", -1);
+        string_dyn_concat (str_commands, cmd_similar->command, -1);
+        found++;
+        if (found >= 5)
+            break;
+    }
+    if (found == 0)
+        string_dyn_concat (str_commands, "-", -1);
+
+    gui_chat_printf_date_tags (
+        NULL,
+        0, GUI_FILTER_TAG_NO_FILTER,
+        _("%sUnknown command \"%s\" (type /help for help), "
+          "commands with similar name: %s"),
+        gui_chat_prefix[GUI_CHAT_PREFIX_ERROR],
+        command,
+        *str_commands);
+
+    string_dyn_free (str_commands, 1);
+    arraylist_free (list_commands);
+}
+
 /*
  * Frees data in a command hook.
  */
diff --git a/src/core/hook/wee-hook-command.h b/src/core/hook/wee-hook-command.h
index 41e28363e..cec93e575 100644
--- a/src/core/hook/wee-hook-command.h
+++ b/src/core/hook/wee-hook-command.h
@@ -65,6 +65,13 @@ struct t_hook_command
     char **cplt_template_args_concat;  /* concatenated arguments            */
 };
 
+struct t_hook_command_similar
+{
+    const char *command;               /* pointer to command name           */
+    int relevance;                     /* lower is better: mostly based on  */
+                                       /* Levenshtein distance between cmds */
+};
+
 extern char *hook_command_get_description (struct t_hook *hook);
 extern struct t_hook *hook_command (struct t_weechat_plugin *plugin,
                                     const char *command,
@@ -78,6 +85,7 @@ extern struct t_hook *hook_command (struct t_weechat_plugin *plugin,
 extern int hook_command_exec (struct t_gui_buffer *buffer, int any_plugin,
                               struct t_weechat_plugin *plugin,
                               const char *string);
+extern void hook_command_display_error_unknown (const char *command);
 extern void hook_command_free_data (struct t_hook *hook);
 extern int hook_command_add_to_infolist (struct t_infolist_item *item,
                                          struct t_hook *hook);
diff --git a/src/core/wee-input.c b/src/core/wee-input.c
index d10cdd038..a287d7152 100644
--- a/src/core/wee-input.c
+++ b/src/core/wee-input.c
@@ -82,6 +82,7 @@ input_exec_command (struct t_gui_buffer *buffer,
 {
     char *command, *command_name, *pos;
     char **old_commands_allowed, **new_commands_allowed;
+    const char *ptr_command_name;
     int rc;
 
     if ((!string) || (!string[0]))
@@ -135,9 +136,11 @@ input_exec_command (struct t_gui_buffer *buffer,
         goto end;
     }
 
+    ptr_command_name = utf8_next_char (command_name);
+
     /* check if command is allowed */
     if (input_commands_allowed
-        && !string_match_list (command_name + 1,
+        && !string_match_list (ptr_command_name,
                                (const char **)input_commands_allowed, 1))
     {
         if (weechat_debug_core >= 1)
@@ -176,11 +179,7 @@ input_exec_command (struct t_gui_buffer *buffer,
             }
             else
             {
-                gui_chat_printf_date_tags (NULL, 0, GUI_FILTER_TAG_NO_FILTER,
-                                           _("%sUnknown command \"%s\" "
-                                             "(type /help for help)"),
-                                           gui_chat_prefix[GUI_CHAT_PREFIX_ERROR],
-                                           command_name);
+                hook_command_display_error_unknown (ptr_command_name);
                 rc = WEECHAT_RC_ERROR;
             }
             break;