Changes: Fix meta-keys that break out of Insert mode

Revision as of 23:42, 2 August 2015

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created 2004 · complexity basic · author Yakov Lerner · version 6.0

On Unix-based systems, the Meta (Alt) key may not work in Vim. For example, in insert mode, pressing Meta-A (Alt-A) may exit to normal mode, then execute normal-mode commands. This can occur with non-GUI Vim under some terminal emulators – those which generate escape sequences for Meta-characters. The actually generated escape-sequences are <Esc>a .. <Esc>z.

Solution

You must manually configure Vim to recognize these escape-sequences as Meta-characters, see below. Terminal emulators which are known to generate these sequences for Meta-keys are: rxvt (unix), putty (PC), teraterm (PC). Vim expects characters 225-250 for Meta-keys.

Here's how to fix Meta-keys on the Vim side:

Check what your Meta-keys generate:

i<press Ctrl-V><press Meta-A>

If you see ^[a (that is, escape character followed by something), then add this snippet to your vimrc:

" fix meta-keys which generate <Esc>a .. <Esc>z
let c='a'
while c <= 'z'
  exec "set <M-".toupper(c).">=\e".c
  exec "imap \e".c." <M-".toupper(c).">"
  let c = nr2char(1+char2nr(c))
endw

To fix Meta-keys definitions manually key-by-key:

:set <M-A>=<press Ctrl-V><press Meta-A>
:imap <press ctrl-v><press Esc>a <M-A>
; repeat each Meta-key.

Don't attempt to map <M-[> or <M-Leader> in this situation. The former will break mouse support (and possibly other things), and the latter doesn't play nicely when exiting insert mode and attempting to perform a leader-bound command.

Comments

Suggested fix does not work in PuTTY on Windows XP, using Vim 6.1.5.

The Vim help files suggest, for example:

:set <M-b>=^[b

This works, but remember to set ttimeoutlen to something small!

Also note, Meta-key mappings are case-sensitive (e.g. <m-b> and <m-B> are different).

--Fritzophrenic 18:02, 30 June 2008 (UTC)

In rxvt I found that the :set <M-a>=^]a commands don't work, instead only the map commands are needed. So I used:

for i in range(65,90) + range(97,122)
  let c = nr2char(i)
  exec "map \e".c." <M-".c.">"
  exec "map! \e".c." <M-".c.">"
endfor

instead of the snippet given above, and everything works fine now.

Jzxu 12:20, 13 March 2009 (UTC)

^] is not ^[, chłopcze

@@ Line 3: / Line 3: @@
 |previous=737
 |next=739
-|created=June 2, 2004
+|created=2004
 |complexity=basic
 |author=Yakov Lerner
@@ Line 11: / Line 11: @@
 |category2=Terminals
 }}
+On Unix-based systems, the Meta (Alt) key may not work in Vim. For example, in insert mode, pressing Meta-A (Alt-A) may exit to normal mode, then execute normal-mode commands. This can occur with non-GUI Vim under some terminal emulators – those which generate escape sequences for Meta-characters. The actually generated escape-sequences are <Esc>a .. <Esc>z.
-Q: My META-keys don't work. When I press META-key in insert mode, they break me out out of insert mode and execute some normal-mode commands.
+==Solution==
-A: This happens with non-GUI Vim under some terminal emulators -- those which generate escape-sequences for META-characters.
+You must manually configure Vim to recognize these escape-sequences as Meta-characters, see below. Terminal emulators which are known to generate these sequences for Meta-keys are: rxvt (unix), putty (PC), teraterm (PC). Vim expects characters 225-250 for Meta-keys.
+Here's how to fix Meta-keys on the Vim side:
-The actually generated escape-sequences are &lt;ESC&gt;a .. &lt;ESC&gt;z.
-You must manually configure Vim to recognize these escape-sequences as META-characters, see below. Terminal emulators which are known to generate these sequences for META-keys are: rxvt (unix), putty (PC), teraterm (PC). Vim expects characters 225-250 for META-keys.
-Here's how to fix META-keys on the Vim side:
-Check what your META-keys generate:
+Check what your Meta-keys generate:
 <pre>
-i&lt;press Ctrl-V&gt;&lt;press Meta-A&gt;
+i<press Ctrl-V><press Meta-A>
 </pre>
-If you see <tt>^[a</tt> (that is, escape character followed by something), then add this snippet to your vimrc:
+If you see <code>^[a</code> (that is, escape character followed by something), then add this snippet to your vimrc:
 <pre>
-" fix meta-keys which generate &lt;esc&gt;a .. &lt;esc&gt;z
+" fix meta-keys which generate <Esc>a .. <Esc>z
 let c='a'
 while c <= 'z'
-  exec "set &lt;M-".toupper(c)."&gt;=\e".c
+  exec "set <M-".toupper(c).">=\e".c
-  exec "imap \e".c." &lt;M-".toupper(c)."&gt;"
+  exec "imap \e".c." <M-".toupper(c).">"
   let c = nr2char(1+char2nr(c))
 endw
 </pre>
-To fix META-keys definitions manually key-by-key:
+To fix Meta-keys definitions manually key-by-key:
 <pre>
-:set &lt;M-A&gt;=&lt;press Ctrl-V&gt;&lt;press Meta-A&gt;
+:set <M-A>=<press Ctrl-V><press Meta-A>
-:imap &lt;press ctrl-v&gt;&lt;press Esc&gt;a &lt;M-A&gt;
+:imap <press ctrl-v><press Esc>a <M-A>
-; repeat each META-key.
+; repeat each Meta-key.
 </pre>
+Don't attempt to map <code>&lt;M-[&gt;</code> or <code>&lt;M-Leader&gt;</code> in this situation. The former will break mouse support (and possibly other things), and the latter doesn't play nicely when exiting insert mode and attempting to perform a leader-bound command.
+==See also==
+*[[VimTip1129|Get Alt key to work in terminal]]
 ==Comments==
 Suggested fix does not work in PuTTY on Windows XP, using Vim 6.1.5.
-The Vim help files suggest:
+The Vim help files suggest, for example:
 <pre>
-:set <M-b>=^]b
+:set <M-b>=^[b
 </pre>
+This works, but remember to set ttimeoutlen to something small!
-This works, but will cause the ESC key followed by an ascii key to basically invoke a mapping. E.g. pressing <ESC> then b (to leave insert mode, then go back a word) will instead insert whatever the ascii code for ALT+b is.
+Also note, Meta-key mappings are case-sensitive (e.g. <m-b> and <m-B> are different).
+--[[User:Fritzophrenic|Fritzophrenic]] 18:02, 30 June 2008 (UTC)
---[[User:Fritzophrenic|Fritzophrenic]] 19:18, 16 June 2008 (UTC)
 ----
+In rxvt I found that the <code>:set <M-a>=^]a</code> commands don't work, instead only the map commands are needed. So I used:
+<pre>
+for i in range(65,90) + range(97,122)
+  let c = nr2char(i)
+  exec "map \e".c." <M-".c.">"
+  exec "map! \e".c." <M-".c.">"
+endfor
+</pre>
+instead of the snippet given above, and everything works fine now.
+[[User:Jzxu|Jzxu]] 12:20, 13 March 2009 (UTC)
+:^] is not ^[, chłopcze