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Thierry Volpiatto edited this page Sep 1, 2024 · 9 revisions

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Helm-grep

Helm grep is a Helm implementation of the grep command, which searches a text file for lines matching a regular expression.

Features include:

  • Incremental
  • Recursive
  • Supports wildcards
  • Allow multi matching
  • Respects grep-find-ignored-files and grep-find-ignored-directories variables
  • Faster than Emacs grep

Usage

From helm-find-files (<helm-prefix> C-x C-f), open the action menu with TAB and choose grep. A prefix argument will launch recursive grep, or .

You can also launch grep directly with (C-u) M-g s without switching to the action menu.

Single file

Just launch grep, it will search in file at point. If the file is a directory, grep will search in all files in the directory like:

grep -nH -e pattern *

Marked files

To grep marked files, just mark some files with C-<space> and launch grep. Marked files can be from different directories.

Recursive

Go to the root of the directory you want to grep in, then hit TAB to open the action menu and choose grep with a prefix argument (C-u).

You will be prompted for types of files to search. Wildcard syntax like \*.el (which searches only files ending in .el) is allowed. With ack-grep you will be prompted instead for ack-grep types, see ack-grep documentation on how define types in your .ackrc file.

By default, the extension of the file at point is used when the cursor is on a file name. If the cursor is at root of a directory, all the file name extensions found in the directory and not matching the variable grep-find-ignored-files are inserted into the prompt.

Persistent action

Persistent action in a Helm grep buffer (C-z) will bring up the buffer corresponding to the file being grepped.

C-u C-z will record the location in the mark ring. If you want to come back later to the grepped location, there is no need to grep again; you can find the locations in the mark ring.

Accessing the mark ring in Emacs is very inconvenient. Fortunately, the helm-all-mark-rings command (in the menu, Tools > Helm > Tools > Browse Mark Ring) brings up a list of all mark rings, both local and global.

Save session

If you want to save the results of your grep session, doing C-x C-s will save your grep results in a helm-grep-mode buffer.

Tip:

  • You can save multiple Helm grep buffers with different names.
  • If you haven’t saved your grep session in a named buffer, you can still retrieve the last session with helm-resume.

Editing the helm-grep-mode buffer is possible with wgrep. Saving this buffer will apply changes to the corresponding files.

Highlight results

By default, Helm applies its own highlights to matched items. However, it may be better to use the backend to highlight result with ANSI sequences.

This can be done by customizing the helm-grep-default-command variable. See the docstring of helm-grep-default-command for more information.

Grep

(setq helm-grep-default-command
      "grep --color=always -d skip %e -n%cH -e %p %f"
      helm-grep-default-recurse-command
      "grep --color=always -d recurse %e -n%cH -e %p %f")

Ack-grep

(setq helm-grep-default-command
      "ack-grep -Hn --color --smart-case --no-group %e %p %f"
      helm-grep-default-recurse-command
      "ack-grep -H --color --smart-case --no-group %e %p %f")

Git-grep

(setq helm-ls-git-grep-command
      "git grep -n%cH --color=always --full-name -e %p %f")

The color of git-grep can be customized from global .gitconfig file.

NOTE: Now --color is enabled everywhere by default. Even if by default grep and ack-grep are using –color You should specify this option to ensure all patterns are highlighted when using multi matches (i.e add a space between each pattern).

Ag (silver-searcher)

(setq helm-grep-ag-command "ag --line-numbers -S --hidden --color --color-match '31;43' --nogroup %s %s %s")
(setq helm-grep-ag-pipe-cmd-switches '("--color-match '31;43'"))

Rg (ripgrep)

(setq helm-grep-ag-command "rg --color=always --colors 'match:fg:black' --colors 'match:bg:yellow' --smart-case --no-heading --line-number %s %s %s")
(setq helm-grep-ag-pipe-cmd-switches '("--colors 'match:fg:black'" "--colors 'match:bg:yellow'"))

Other search tools

Helm grep supports other tools like ag, pt, rg and git-grep.

Both ag, pt and rg can be used with helm-do-grep-ag. The variable helm-grep-ag-command controls the exact command used, see its docstring for more infos.

git-grep can be used with helm-grep-do-git-grep, see git-grep documentation for configuring .gitconfig.

TRAMP

Helm grep works with TRAMP (you can grep a file on a remote host or in su/sudo methods), but TRAMP has poor support for multiple processes launched with short delays (< 5 seconds) between them.

Therefore, you should suspend Helm updates with C-! while you write your regexp. Once done, hit again C-! to restart Helm updates. If you don’t, Helm grep should still work, but it will be slow and may result in occasional failures.

Platforms

OS X

Apple OS X users need a version of grep that accepts --exclude-dir. Install it from Homebrew with:

brew tap homebrew/dupes
brew install homebrew/dupes/grep

You should also set helm-grep-default-command to use ggrep instead of grep.

Windows

Windows users need grep version 2.5.4 of Gnuwin32. This version should accept the --exclude-dir option.

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