suppose i have the following in a text file (or dired buffer) open in emacs:
file_01.txt
file_02.txt
...
file_99.txt
I want to query-replace or replace the files to
01_file.txt, etc.
I want to use query-replace-regexp or replace-regexp, but don't know what to put in. The search part i put in "file_..", but the ".." are read as periods in the replacement string. I'm beginning to learn regexp and don't know how to do this. Please help, thanks.
M-x replace-regexp invokes the function to replace with regular expressions.
For Replace regexp enter: \(file\)_\([0-9]+\)
This will create two groups, one that matches the 'file' part, and one that matches the number. The braces \( ... \) are necessary to make the match available later in the replacement string.
For Replace with enter: \2_\1
This inserts the second match from the search string (the numeric part), adds the _ (underscore) and then adds the first match from the search string (the 'file').
For more information on Emacs' regular expressions, see Regexp Syntax and Regexp Replace.
Once you have mastered the regexp basics you might want to check out the Emacs ReBuilder tool with M-x re-builder, which lets you build regexes interactively.
Related
I have a bunch of artists that are named in this fashion:
Killers, The
Treatment, The
Virginmarys, The
I need them to look like
The Killers
The Treatment
The Virginmarys
I'm able to match the lines with , The ((^|\n)(.*, The) is what I've used) but the more advanced syntax is eluding me. I can use regex on the replacement syntax as well (it's for a TextPipe filter so it might as well be for Notepad++ or any other Regex text editor).
You should be able to use the following:
Find: (\S+),\s\S*
Replace: The $1
Or include the The..
Find: (\S+),\s+(\S+)
Replace: $2 $1
Depending on your editor, you may be better off using \1, \2, and so on for capture groups.
Since you need to specifically capture the title before the comma, do so:
(^|\n)(.*), The
And replace it putting the "the" in the right place:
\1The \2
Regular expressions define matches but not substitutions.
How and in which way you can perform substitutions is highly dependant on the application.
Most editors that provide regular expression support work on a line per line basis.
Some of them will allow substitutions such as
s/^(.*Banana)/INSERTED LINE\n\1/
which would then insert the specific pattern before each match. Note that others may not allow newlines in the substitution pattern at all. In VIM, you can input newlines into the command prompt using Ctrl+K Return Return. YMMV.
In Java, you would just first print the insertion text, then print the matching line.
I am facing a problem whereby I am given a string that contains a path to a file and the file's name and I only want to extract the path (without the file's name)
For example, I will receive something like
C:\Users\OopsD\Projects\test.acdbd
and from that string I want to extract only
C:\Users\OopsD\Projects
I was trying to create a RegEx to match a backslash followed by a word, followed by a dot followed by another word - this is to match the
\test.acdbd
part and replace it with empty string so that the final result is
C:\Users\OopsD\Projects
Can anyone, familiar with RegEx, help me on this one? Also, I will be using regular expressions quite a lot in the future. Is there a (free) program I can download to create regular expressions?
Are you really sure you need to be using Regex for such as simple task? How about this:
Dim file As New IO.FileInfo(" C:\Users\OopsD\Projects\test.acdbd")
MsgBox(file.Directory.FullName)
Regarding the free program on Regex, I would definitely recommend http://www.gskinner.com/RegExr/ - using it all the time. But you always have to consider alternatives, before going the Regex way.
The regex that you are looking for is as below:
[^/]+$
where,
^ (caret):Matches at the start of the string the regex pattern is applied to. Matches a position rather than a character. Most regex flavors have an option to make the caret match after line breaks (i.e. at the start of a line in a file) as well.
$ (dollar):Matches at the end of the string the regex pattern is applied to. Matches a position rather than a character. Most regex flavors have an option to make the dollar match before line breaks (i.e. at the end of a line in a file) as well. Also matches before the very last line break if the string ends with a line break.
+ (plus):Repeats the previous item once or more. Greedy, so as many items as possible will be matched before trying permutations with less matches of the preceding item, up to the point where the preceding item is matched only once.
More reference can be found out at this link.
Many Regex softwares and tools are out there. Some of them are:
www.gskinner.com/RegExr/
www.txt2re.com
Rubular- It is not just for Ruby.
How can I delete some text that match with a regex in emacs?
I suppose that using:
'(query-replace-regexp PATTERN EMPTY)
and:
'(replace-regexp PATTERN EMPTY)
but they throw:
perform-replace: Invalid regexp: "Premature end of regular expression".
In general, you can delete text that matches a given regexp by using the empty string "" as the replacement in the two functions you mention. However, as others mentioned in the comments above, your regular expression is faulty.
For instance, if your buffer contains the following text:
1. My todo list
1.1. Brush teeth
1.2. Floss
2. My favorite movies
2.1. Star Wars episodes 4-6
and you would like to get rid of the numbers at the beginning of each line, you could place the cursor at the beginning of the buffer and then type M-C-% (that is, you press at a time: ALT, CTRL, Shift, 5) to invoke the command query-replace-regexp. You'll get asked two parameters in the minibuffer, first the regexp to match than the replacement string.
So, in our example, you could use the following regexp:
\([0-9]\.\)+\s-
as the first parameter, and simply hit ENTER for the second parameter, i.e., don't specify anything as the replacement. That way, the replacement is the empty string: you replace what ever matches the regexp with nothing.
query-replace-regexp will ask you interactively for every match if you want to replace it or if you want to skip it. This is the "query"-part in query-replace-regexp and it is helpful to see if the regexp you came up with actually matches what you thought it does. If you're sure it does, you can type ! to make Emacs replace the remaining matches without asking every time.
If you use M-x replace-regexp instead of M-C-% Emacs will replace every match without asking for input at every match.
For the special case that you'd like to delete whole lines when a certain part of the line matches a regexp, there's also delete-matching-lines and its evil, goatee-wearing twin brother from a parallel universe delete-non-matching-lines.
I've got a string:
doCall(valA, val.valB);
Using a regex in GVIM I would like to change this to:
valA = doCall(valA, val.valB);
How would I go about doing this? I use %s for basic regex search and replace in GVIM, but this a bit different from my normal usages.
Thanks
You can use this:
%s/\vdoCall\(<(\w*)>,/\1 = doCall(\1,/
\v enables “more magic” in regular expressions – not strictly necessary here but I usually use it to make the expressions simpler. <…> matches word boundaries and the in-between part matches the first parameter and puts it in the first capture group. The replacement uses \1 to access that capture group and insert into the right two places.
I'm a regexp newbie and I would like to know how to do a search and replace for the following case:
A file contains many occurrences of the following:
L1234_XL3.ext
and also many occurrences of:
L1234_XL3
I only want to find and replace L1234_XL3 occurrences with XL3 without affecting instances that have an extension.
I am using notepad++ to do the regular expression.
If Notepad++ supports lookaheads, you can simply use L1234_XL3(?!\.ext) for the search and "XL3" for the replacement.
EDIT: Looks like it doesn't support lookaheads after all. A pity; you'll have to do it the hard way without regexes (regexen?):
Replace L1234_XL3.ext with QQQ (or any other string that doesn't appear in the file)
Replace L1234_XL3 with XL3.
Replace QQQ with L1234_XL3.ext.
Step 1.
Change all occurences of L1234_XL3.ext to L-1-2-3-4_XL3.ext (for example)
Step 2.
Change all occurences of L1234_XL3 to XL3
Step 3.
Change all occurences of L-1-2-3-4_XL3.ext back to L1234_XL3.ext
As far as I understand Notepad++ 5.4.5 doesn't support positive lookahead