Emacs: Search Text in Current File

isearch, Interactive Search

The most useful one is “isearch”.

isearch-forward 【Ctrl+s】

Interactive search text in current buffer.

While in isearch prompt:

• Ctrl+s → Jump to next occurrence
• Ctrl+r → Jump to previous occurrence.
• Ctrl+g → Exit and place cursor at original position.
• Enter → Exit and place cursor at current position.

Case Sensitivity in Isearch

By default, search is Case-Insensitive unless your search string contains Capital Letter.

While in isearch, press Alt+s c to toggle search case-sensitivity.

Or, Alt+x toggle-case-fold-search before isearch. Remember to toggle it back.

Search Word Under Cursor

While in isearch, press Ctrl+w to select more words to the right of cursor.

The following commands do isearch but use the word under cursor.

isearch-forward-symbol-at-point 【Alt+s .】

Search the “symbol” under cursor, with boundary check.

Boundary check means, if current word or symbol is “xy”, it will not find “xy2”.

isearch-forward-word 【Alt+s w】

Search the word under cursor, with boundary check.

• Emacs WORD usually means alphanumeric and hyphen.
• SYMBOL means programing language's identifier.
• Whether LOW LINE _ or HYPHEN-MINUS - is part of symbol or word depends on current Syntax Table, which is set by Major Mode

isearch-forward-symbol 【Alt+s _】

similar to isearch but with boundary check.

isearch Keys

isearch has many complex features. You can read about them by:

• Alt+x isearch-describe-mode
• Alt+x isearch-describe-bindings

I don't recommend using them because they are very complex. If you need regex search, use Alt+x list-matching-lines 〔see Emacs: List Matching Lines〕