Update README: Advanced topics

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Junegunn Choi 2017-07-29 17:08:51 +09:00
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@ -46,6 +46,9 @@ Table of Contents
* [Settings](#settings) * [Settings](#settings)
* [Supported commands](#supported-commands) * [Supported commands](#supported-commands)
* [Vim plugin](#vim-plugin) * [Vim plugin](#vim-plugin)
* [Advanced topics](#advanced-topics)
* [Performance](#performance)
* [Preview window](#preview-window)
* [Tips](#tips) * [Tips](#tips)
* [Respecting .gitignore, <code>.hgignore</code>, and <code>svn:ignore</code>](#respecting-gitignore-hgignore-and-svnignore) * [Respecting .gitignore, <code>.hgignore</code>, and <code>svn:ignore</code>](#respecting-gitignore-hgignore-and-svnignore)
* [git ls-tree for fast traversal](#git-ls-tree-for-fast-traversal) * [git ls-tree for fast traversal](#git-ls-tree-for-fast-traversal)
@ -387,6 +390,87 @@ Vim plugin
See [README-VIM.md](README-VIM.md). See [README-VIM.md](README-VIM.md).
Advanced topics
---------------
### Performance
fzf is fast, and is [getting even faster][perf]. Performance should not be
a problem in most use cases. However, you might want to be aware of the
options that affect the performance.
- `--ansi` tells fzf to extract and parse ANSI color codes in the input and it
makes the initial scanning slower. So it's not recommended that you add it
to your `$FZF_DEFAULT_OPTS`.
- `--nth` makes fzf slower as fzf has to tokenize each line.
- `--with-nth` makes fzf slower as fzf has to tokenize and reassemble each
line.
- If you absolutely need better performance, you can consider using
`--algo=v1` (the default being `v2`) to make fzf use faster greedy
algorithm. However, this algorithm is not guaranteed to find the optimal
ordering of the matches and is not recommended.
[perf]: https://junegunn.kr/images/fzf-0.16.10.png
### Executing external programs
You can set up key bindings for starting external process in the foreground
(`execute`) or in the background (`execute-silent`).
```sh
# Press F1 to open the file with less without exiting fzf
# Press CTRL-Y to copy the line to clipboard and aborts fzf (requires pbcopy)
fzf --bind 'f1:execute(less -f {}),ctrl-y:execute-silent(echo {} | pbcopy)+abort'
```
See *KEY BINDINGS* section of the man page for details.
### Preview window
When `--preview` option is set, fzf automatically starts external process with
the current line as the argument and shows the result in the split window.
```sh
# {} is replaced to the single-quoted string of the focused line
fzf --preview 'cat {}'
```
Since preview window is updated only after the process is complete, it's
important that the command finishes quickly.
```sh
# Use head instead of cat so that the command doesn't take too long to finish
fzf --preview 'head -100 {}'
```
Preview window supports ANSI colors, so you can use programs that
syntax-highlights the content of a file.
- Highlight: http://www.andre-simon.de/doku/highlight/en/highlight.php
- CodeRay: http://coderay.rubychan.de/
- Rouge: https://github.com/jneen/rouge
```sh
# Try highlight, coderay, rougify in turn, then fall back to cat
fzf --preview '[[ $(file --mime {}) =~ binary ]] &&
echo {} is a binary file ||
(highlight -O ansi -l {} ||
coderay {} ||
rougify {} ||
cat {}) 2> /dev/null | head -500'
```
You can customize the size and position of the preview window using
`--preview-window` option. For example,
```sh
fzf --height 40% --reverse --preview 'file {}' --preview-window down:1
```
For more advanced examples, see [Key bindings for git with fzf][fzf-git].
[fzf-git]: https://junegunn.kr/2016/07/fzf-git/
Tips Tips
---- ----