Search commands move though the buffer, in either the forward or the reverse direction, looking for text that matches a search pattern. Search commands prompt for the search pattern in the echo line. The search pattern used by the last search command is remembered, and displayed in the prompt. If you want to use this pattern again, just hit carriage return at the prompt.

In search strings, all characters stand for themselves, and all searches are normally case insensitive. The case insensitivity may be defeated with the "fold-case" command, described below. The newline characters at the ends of the lines are considered to have hexadecimal value 0A, and can be matched by a linefeed (Ctrl-J) in the search string.

ce supports Crystal regular expressions. Here is a very small subset of what regular expressions allow:

• . (dot) matches any character

• character classes (square brackets with optional ^ negation operator)

• groups (parentheses)

• alternatives (|)

• ^ (start of line) and $ (end of line)

• ? (zero or one occurrence)

• * (zero or more occurrences)

• + (one or more occurrences)

C-S (forw-search)

Search forward, from the current location, toward the end of the buffer. If found, dot is positioned after the matched text. If the text is not found, dot does not move.

C-R (back-search)

Search reverse, from the current location, toward the front of the buffer. If found, dot is positioned at the first character of the matched text. If the text is not found, dot does not move.

M-C-S (forw-regexp-search)

Similar to forw-search, except that the search string is a regular expression, and searches cannot cross line boundaries.

M-C-R (back-regexp-search)

Similar to back-search, except that the search string is a regular expression, and searches cannot cross line boundaries.

M-C-F (fold-case)

Enable or disable case folding in searches, depending on the argument to the command. If the argument is zero, case folding is disabled, and searches will be sensitive to case. If the argument is non-zero, case folding is enabled, and searches will NOT be sensitive to case.

M-P (search-paren)

Search for a match of the character at the dot. If the character is a parenthesis or bracketing character, move the dot to the matching parenthesis or bracket, taking into account nesting and C-style comments. A parenthesis or bracketing character is one of the following: (){}[]<>

F9 (search-again)

Repeat the last search command (of any type) without prompting for a string.

M-Q (query-replace)

Search and replace with query. This command prompts for a search string and a replace string, then searches forward for the search string. After each occurrence of the search string is found, the dot is placed after the string, and the user is prompted for action. Enter one of the following characters:

• space or , (comma) causes the string to be replaced, and the next occurrence is searched.

• . (period) causes the string to replaced, and quits the search.

• n causes the string to be skipped without being replaced, and the next occurrence is searched.

• ! causes all subsequent occurrences of the string to be replaced without prompting.

• Control-G aborts the search without any further replacements.

M-R (replace-string)

Prompt for a search string and a replacement string, then search forward for all occurrences of the search string, replacing each one with the replacement string. Do not prompt the user for confirmation at each replacement, as in the query-replace command.

M-? (reg-query-replace)

Similar to query-replace, except that the search string is a regular expression. The replacement string can contain the following special sequences:

• \0 stands for the entire matched string.

• \n, where n is a digit in the range 1-9, stands for the nth matched group (where groups are delineated by parentheses in the regular expression pattern).

• \ followed another \ stands for a single \.

M-/ (reg-replace)

Similar to reg-query-replace, except that the user is not prompted to confirm each replacement, as in replace-string.

C-X I (spell-region)

This command uses aspell to spell-check the current region (the text between the mark and the dot). At each misspelled word, ce pops up a window showing the suggested replacements, and prompts for an replacement:

• Entering a blank string ignores the misspelled word and adds it to aspell's list of words to ignore in the future.

• Entering a number replaces the misspelled word with the matching suggested replacement in the popup window.

• Entering any other string replaces the misspelled word with that string.

• Entering Ctrl-G aborts the command.

If you want aspell to use a language other than the default, install the desired aspell-LANG package, and then add a spelling_language key/value pair to the appropriate section of an EditorConfig file.

M-$ (spell-word)

Similar to spell-region, except that it checks only the word under the cursor.