Linux Keyboard Tips

Miscellaneous hacks to use the keyboard under Linux.

Special Characters on X11

The compose key, when pressed in sequence with other keys, produces a Unicode character. E.g., in most configurations pressing Compose e ``` produces é. Compose keys appeared on some computer keyboards decades ago, especially those produced by Sun Microsystems. However, it can be enabled on any keyboard with setxkbmap. For example, compose can be set to right alt by running:

setxkbmap -option compose:ralt

Compose Sequences

    |   no-break space                      ¦  broken bar              ||
    ­  soft hyphen             --           µ  micro sign              /U
    ¡  inverted !              !!           ¿  inverted ?              ??
    ¢  cent sign            C/ or C|        £  pound sign           L- or L=
    ¤  currency sign        XO or X0        ¥  yen sign             Y- or Y=
    §  section sign         SO or S! or S0  ¶  pilcrow sign            P!
    ¨  diaeresis            "" or  "        ¯  macron               _^ or -^
    ´  acute accent            ''           ¸  cedilla                 ,,
    ©  copyright sign       CO or C0        ®  registered sign         RO
    ª  feminine ordinal        A_           º  masculine ordinal       O_
    «  opening angle brackets  <<           »  closing angle brakets   >>
    °  degree sign             0^           ¹  superscript 1           1^
    ²  superscript 2           2^           ³  superscript 3           3^
    ±  plus or minus sign      +-           ¼  fraction one-quarter    14
    ½  fraction one-half       12           ¾  fraction three-quarter  34
    ·  middle dot           .^ or ..        ¬  not sign                -,
    ×  multiplication sign     xx           ÷  division sign           :-

    À  A grave                 A`           à  a grave                 a`
    Á  A acute                 A'           á  a acute                 a'
       A circumflex            A^           â  a circumflex            a^
    Ã  A tilde                 A~           ã  a tilde                 a~
    Ä  A diaeresis             A"           ä  a diaeresis             a"
    Å  A ring                  A*           å  a ring                  a*
    Æ  AE ligature             AE           æ  ae ligature             ae

    Ç  C cedilla               C,           ç  c cedilla               c,

    È  E grave                 E`           è  e grave                 e`
    É  E acute                 E'           é  e acute                 e'
    Ê  E circumflex            E^           ê  e circumflex            e^
    Ë  E diaeresis             E"           ë  e diaeresis             e"

    Ì  I grave                 I`           ì  i grave                 i`
    Í  I acute                 I'           í  i acute                 i'
    Î  I circumflex            I^           î  i circumflex            i^
    Ï  I diaeresis             I"           ï  i diaeresis             i"

    Ð  capital eth             D-           ð  small eth               d-

    Ñ  N tilde                 N~           ñ  n tilde                 n~

    Ò  O grave                 O`           ò  o grave                 o`
    Ó  O acute                 O'           ó  o acute                 o'
    Ô  O circumflex            O^           ô  o circumflex            o^
    Õ  O tilde                 O~           õ  o tilde                 o~
    Ö  O diaeresis             O"           ö  o diaeresis             o"
    Ø  O slash                 O/           ø  o slash                 o/

    Ù  U grave                 U`           ù  u grave                 u`
    Ú  U acute                 U'           ú  u acute                 u'
    Û  U circumflex            U^           û  u circumflex            u^
    Ü  U diaeresis             U"           ü  u diaeresis             u"

    Ý  Y acute                 Y'           ý  y acute                 y'

    Þ  capital thorn           TH           þ  small thorn             th

    ß  German small sharp s    ss           ÿ  y diaeresis             y"

      Euro                    e=

Environment variables

Some unfriendly applications (including many GTK apps) will override the compose key and default to their own built-in combinations. You can typically fix this by setting environment variables; for instance, you can fix the behavior for GTK with:

export GTK_IM_MODULE=xim