regex

gistfile1.txt

    .           Any char except newline,
    ?           zero or one,
    *           zero or more,
    +           one or more, \+ in vim.
    \           quote, match next char literally,
    \Number     of match of left open paren,
    [a-z]       in char-class,
    [^a-z]      not in char class,

        ---------------------------------------------------------
        Emacs           Perl            Vim
        ---------------------------------------------------------
        \|              |               |       Alternative.
        \< \>           \b              \< \>   Word begin/end.
        ^  $            ^  $            ^ $     Line begin/end.
        \` \'           \A \Z                   Buffer begin/end.
        \sw \Sw         \w \W           \w \W   Word char, not a word char.
        [0-9]           \d \D           \d \D   Digit, not a digit.
        \s- \S-         \s \S           \s \S   Space, not a space.
                        [a-zA-Z]        \a \A   Alphabetic
                        [a-z]           \l \L   Lower, not.
                        [A-Z]           \u \U   Upper, not.
        +               +               \+      One or more.
                                        \{n,m}  m..n (greedy).
        \( \)           ( )             \( \)   Grouping.
        \1              $1              \1      Group 1 that matched.
        \&              $&              &       Whole match for re.
                                        ~       Last subst.
                                        :set magic
                                        :help regexp for non-eager.
        ---------------------------------------------------------

    Vim6 Regexp
        ---------------------------------------------------------
        \?                     0 or 1 (greedy).
        \=                     0 or 1 (greedy).
        \{n,m} \{-n,m}         m..n   (greedy,non-greedy).
        \{n}   \{-n}           n      (greedy,non-greedy).
        \{,m}  \{-,m}          0..m   (greedy,non-greedy).
        *      \{-}            0..more (greedy,non-greedy).
        \_.                    [.\n]
        \%^ \^# \%$            bof, cursor/point, eof.
        \%23l \%23c \23v       line 23, column 23, vcolumn 23.
        \L \l \U \u \D \d      alphabets (not)lower,(not)upper,(not)digit.
        \p                     printable.
    Directives
        \c \C \M \m \V \v      (no)case,(no)magic,(no)very-magic-perl.
        ---------------------------------------------------------


    ksh patterns
    ---------------------------------------------------------
    ?                Matches one file char except / and a . at the beginning of a file name.
    *                Matches >= 0, same restrictions as ?.
    ?(pattern-list)  Matches 0,1 of pattern-list.
    *(pattern-list)  Matches zero or more of pattern-list.
    +(pattern-list)  Matches >= 1, of pattern-list.
    @(pattern-list)  Matches == 1, of pattern-list.
    !(pattern-list)  Matches any string that does not match pattern-list.
    ---------------------------------------------------------