30
votes
Accepted
Only show lines containing phrase/regex
...see all the lines from the current buffer...
With built-in commands and no external packages or dependencies in
a new buffer, use:
M-x occur
the same buffer, use:
M-x keep-lines
- 5,603
30
votes
Accepted
how do I quickly remove lines from emacs buffer
You can go to beginning of buffer with M-<, then M-x flush-lines, type your word and hit RET.
(flush-lines REGEXP &optional RSTART REND INTERACTIVE)
Delete lines containing matches for ...
- 1,350
22
votes
Accepted
Incrementally replace a given string
General technique
Your replacement string can contain arbitrary lisp code. From the documentation for replace-regexp:
In interactive calls, the replacement text may contain ‘\,’ followed by a Lisp ...
- 9,032
18
votes
support for regex look behind and ahead?
No, Emacs regular expressions do not support arbitrary zero-width look-ahead/behind assertions.
n.b. Evil and Spacemacs (like all elisp libraries) are irrelevant when it comes to questions about the ...
- 49.8k
16
votes
Accepted
Search through the values of all variables in Emacs
Does apropos-value do what you're looking for?
(apropos-value PATTERN &optional DO-ALL)
Show all symbols whose value’s printed representation matches PATTERN.
PATTERN can be a word, a list of ...
- 471
16
votes
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
The built-in library subr-x.el has included the inline functions string-trim-left, string-trim-right, and string-trim ...
- 12.2k
13
votes
Accepted
Is there any principal difference between "A-Z" and upper?
The macro rx returns regexp strings that can be passed to other Emacs functions.
ELISP> (rx (one-or-more (any upper lower)))
"[[:lower:][:upper:]]+"
ELISP> (rx (one-or-more (any "A-Z" "a-z")))
"...
- 9,032
11
votes
Is there an equivalent of string-match for regexp?
For the sake of an answer:
string-match is meant for to be used with regexps.
(string-match REGEXP STRING &optional START)
Return index of start of first match for REGEXP in STRING, or ...
- 12.4k
11
votes
Accepted
What does a backslash followed by a single quote mean in a regular expression?
It's a special construct in emacs regexp that matches the end of a string (not just the end of a line). Quoting the the manual
\'
matches the empty string, but only at the end of the string or ...
- 1,510
11
votes
Accepted
How to apply arithmetic operators to query-replace-regex
\2 in your replacement is a string, and it needs to be a number in order to perform the division.
You could convert it to a number using string-to-number, but there's in-built shorthand for treating ...
- 4,850
9
votes
Accepted
Most performant matching of "any char"
In Emacs's regexps, . does not match all characters. It is a synonym of [^\n]. So the reason for using [\0-\377[:nonascii:]] is when you want to match "any char, even a newline".
W.r.t overflowing ...
- 26.3k
9
votes
Accepted
Regexp replace to match a string, but not match a superstring
Try \_<Vector\_>. The \_< construct matches the empty string, but only at the beginning of a symbol. \_> is the same, but at the end of a symbol. What is a "symbol" depends on the buffer's ...
- 28.2k
9
votes
What's the idiomatic (or best) way to trim surrounding whitespace from a string?
There is the string manipulation library s.el where trimming whitespace and newlines at the beginning and the end of a string is implemented as function s-trim. I cite that function here with its ...
- 32.8k
8
votes
Accepted
Escaping brackets in regexp
Try this:
(if (looking-at "\\[") (insert "f"))
Usually you will need to escape your escaping backslash. This tutorial has a short explanation of the "double backslash".
When in doubt, I always use ...
- 4,775
8
votes
Accepted
How to use the regexp for digits with an interactive search?
As far as I can tell, there is no \d in Emacs regular
expressions.
So, @Tobias's comment is (mostly) correct, except that you need to
escape the curly brackets. Either of the following will work:
`C-...
Dan♦
- 32.7k
8
votes
Accepted
Evil mode and regular expressions
evil uses the Emacs regexp facilities under the hood. Unfortunately, Emacs does not appear to have a separate syntax
class for digits, and does not recognize the \d regexp class.
So, to match your ...
Dan♦
- 32.7k
8
votes
Accepted
Multiple URL formats for bug-reference-mode
Update
Starting with Emacs 28, bug-reference is able to automatically detect and configure itself for Git forges including GitHub and GitLab. Quoth (info "(emacs) Bug Reference"):
[...]
...
- 12.2k
8
votes
Accepted
Enable mode if file content contains a matching string
I would like to enable [some mode] whenever a file I open contains a specific string, or a regex
This is exactly what magic-mode-alist is for (there is also magic-fallback-mode-alist if you want the ...
- 9,083
8
votes
Accepted
Find and remove consecutive duplicated words while ignoring case
You can query-replace-regexp as follows:
\(\b\w+\b\)\W+\1\b → \1
This means, match a whole word (\b\w+\b), followed by non word characters (\W+), followed by the first word (\1) and a word ending (\...
- 5,435
8
votes
Whitespace and newlines in regexps?
You could always use one of the character classes. I would say use [:blank:] when the usage context is textual, and use [:space:] when it is programmatic, i.e. plain text vs source code.
When ...
- 1,588
8
votes
Accepted
Regex for the last line of a string
$ matches at the end of a line, not the end of a string. If you want to match at the end of a string you need to use the \' operator:
(string-match "\n.*\\'" "\n \n \n ")
=> 4
...
- 4,850
7
votes
replace-regexp: invalid use of \ in replacement text
To make clear the accepted answer in the comments:
M-x replace-regexp ^([0-9]\{1,2\}) RET \exx\{ RET
^^
should be
M-x replace-regexp ^([0-9]\{1,2\}) RET ...
- 888
7
votes
Accepted
Regexp replace without interaction
Use replace-regexp (note the absence of the query- prefix).
But also, note the ! keybinding when running query-replace-regexp. It will replace all occurences beyond point without further questions.
- 2,421
7
votes
Accepted
Why does adding grouping parentheses cause a regexp to no longer match?
You need to escape the \ on your \(...\) to read \\(...\\):
(string-match "^\\([^XY]+X\\)" "fooXbarXbazXextraYstuff") ; => 0
Dan♦
- 32.7k
7
votes
Accepted
7
votes
Accepted
How do I match a closing bracket in Emacs lisp
Put the ] as the first character after the [ which starts the character class, e.g.
[])}]
This is the manual page
- 1,904
7
votes
Accepted
How can I use more than 9 regex capture groups in Emacs Lisp?
Going by the Emacs source code, it is absolutely possible to use more than 9 regex capture groups:
/* Since we have one byte reserved for the register number argument to
{start,stop}_memory, the ...
- 22k
7
votes
emacs regex with multiple match for text, in multi line buffer
You can use the following regexp
This is test\(.*\n\)+?shoes>\nshoes/\n
.*\n matches a line
+? matches multiple lines in non-greedy way
Using the regexp in C-M-s (isearch-forward-regexp):
Note: ...
- 14.4k
Only top scored, non community-wiki answers of a minimum length are eligible