#### Indexing method

Projectile has two modes of operation - one is portable and is implemented in Emacs Lisp(therefore it's native to Emacs and is known as the `native indexing method`) and the other relies on external commands like `find`, `git`, etc to obtain the list of files in a project.

Since the native indexing mode is much slower, by default the second method is used on all operating systems except Windows. To force the use of native indexing in operating systems other than Windows:

    (setq projectile-indexing-method 'native)

To force the use of external indexing in Windows:

    (setq projectile-indexing-method 'alien)

This can speed up Projectile in Windows significantly. The disadvantage of this method is that it's not well supported on Windows systems. If there's problem, you can always use native indexing mode.

#### Caching

##### Project files

Since indexing a big project is not exactly quick (especially in Emacs Lisp), Projectile supports caching of the project's files. The caching is enabled by default whenever native indexing is enabled.

To enable caching unconditionally use this snippet of code:

    (setq projectile-enable-caching t)

At this point you can try out a Projectile command such as `C-c p f` (`M-x projectile-find-file RET`).

Running `C-u C-c p f` will invalidate the cache prior to prompting you for a file to jump to.

Pressing `C-c p z` will add the currently visited file to the cache for current project. Generally files created outside Emacs will be added to the cache automatically the first time you open them.

The project cache is persistent and will be preserved during Emacs restarts.

You can purge an individual file from the cache with `M-x projectile-purge-file-from-cache` or an entire directory with `M-x projectile-purge-dir-from-cache`.

##### File exists cache

Projectile does many file existence checks since that is how it identifies a project root. Normally this is fine, however in some situations the file system speed is much slower than usual and can make emacs "freeze" for extended periods of time when opening files and browsing directories.

The most common example would be interfacing with remote systems using TRAMP/ssh. By default all remote file existence checks are cached

To disable remote file exists cache that use this snippet of code:

    (setq projectile-file-exists-remote-cache-expire nil)

To change the remote file exists cache expire to 10 minutes use this snippet of code:

    (setq projectile-file-exists-remote-cache-expire (* 10 60))

You can also enable the cache for local file systems, that is normally not needed but possible:

    (setq projectile-file-exists-local-cache-expire (* 5 60))

#### Using Projectile everywhere

If you want Projectile to be usable in every directory (even without the presence of project file):

    (setq projectile-require-project-root nil)

This might not be a great idea if you start Projectile in your home folder for instance. :-)

#### Switching projects

When running `projectile-switch-project` (`C-c p p`) Projectile invokes the command specified in `projectile-switch-project-action` (by default it is `projectile-find-file`).

Depending on your personal workflow and habits, you may prefer to alter the value of `projectile-switch-project-action`:

###### `projectile-find-file`

This is the default. With this setting, once you have selected your project via Projectile's completion system (see below), you will remain in the completion system to select a file to visit. `projectile-find-file` is capable of retrieving files in all sub-projects under the project root, such as Git submodules. Currently, only Git is supported. Support for other VCS will be added in the future.

###### `projectile-find-file-in-known-projects`

Similar to `projectile-find-file` but lists all files in all known projects. Since the total number of files could be huge, it is beneficial to enable caching for subsequent usages.

###### `projectile-find-file-dwim`

If point is on a filepath, Projectile first tries to search for that file in project:

- If it finds just a file, it switches to that file instantly. This works even if the filename is incomplete, but there's only a single file in the current project that matches the filename at point. For example, if there's only a single file named "projectile/projectile.el" but the current filename is "projectile/proj" (incomplete), projectile-find-file still switches to "projectile/projectile.el" immediately because this is the only filename that matches.

- If it finds a list of files, the list is displayed for selecting. A list of files is displayed when a filename appears more than one in the project or the filename at point is a prefix of more than two files in a project. For example, if `projectile-find-file' is executed on a filepath like "projectile/", it lists the content of that directory. If it is executed on a partial filename like "projectile/a", a list of files with character 'a' in that directory is presented.

- If it finds nothing, display a list of all files in project for selecting.

###### `projectile-dired`

    (setq projectile-switch-project-action 'projectile-dired)

With this setting, once you have selected your project, the top-level directory of the project is immediately opened for you in a dired buffer.

###### `projectile-find-dir`

    (setq projectile-switch-project-action 'projectile-find-dir)

With this setting, once you have selected your project, you will remain in Projectile's completion system to select a sub-directory of your project, and then that sub-directory is opened for you in a dired buffer. If you use this setting, then you will probably also want to set

    (setq projectile-find-dir-includes-top-level t)

in order to allow for the occasions where you want to select the top-level directory.

#### Completion Options

##### Ido

By default Projectile uses `ido` as its completion system. `ido` is extremely popular and it is built into Emacs.

As already noted above if you're going to use the `ido` completion it's extremely highly recommended that you install the optional flx-ido package, which provides a much more powerful alternative to `ido`'s built-in `flex` matching.

##### Grizzl

Another completion option is grizzl:

    (setq projectile-completion-system 'grizzl)

`grizzl`'s advantage is that it provides good fuzzy completion (compared to `ido`'s less than stellar built-in flex matching, but inferior to `ido-flx`).

##### Basic (Emacs's default)

If you don't like `ido` and `grizzl` you can use regular completion:

    (setq projectile-completion-system 'default)

You might want to combine default completion with `icomplete-mode` for optimum results.

##### Custom Completion Function

You can also set `projectile-completion-system` to a function:

    (setq projectile-completion-system 'my-custom-completion-fn)
    (setq projectile-completion-system
          (lambda (prompt choices)
            ;; ...
            ))

An example of a custom completion function is this one, which only show the file name (not including path) and if the file selected is not unique, another completion with names relative to project root appears.

##### Regenerate tags

To be able to regenerate a project's tags via `projectile-tags-command`, you should install Exuberant Ctags (`apt-get install exuberant-ctags`) instead of a plain ctags, which ships with Emacs distribution.

### Customizing project root files

You can set the values of `projectile-project-root-files`, `projectile-project-root-files-top-down-recurring`, `projectile-project-root-files-bottom-up` and `projectile-project-root-files-functions` to customize how project roots are identified.

To customize project root files settings:

    M-x customize-group RET projectile RET

#### File-local project root definitions

If you want to override the projectile project root for a specific file, you can set the file-local variable `projectile-project-root`. This can be useful if you have files within one project that are related to a different project (for instance, Org files in one git repo that correspond to other projects).

### Storing project settings

From project to project some things may differ even in same language - different coding styles, separate auto-completion sources, etc. If you need to set some variables according to selected project, you can use standard Emacs feature called Per-Directory Local Variables. To use it you must create file named `.dir-locals.el` inside project directory. This file must contain something like this:

    ((nil . ((secret-ftp-password . "secret")
             (compile-command . "make target-x")
             (eval . (progn
                       (defun my-project-specific-function ()
                         ;; ...
                         ))))
     (c-mode . (c-file-style . "BSD")))

The top-level alist member referenced with the key `nil` applies to the entire project. A key with the name `eval` will evaluate its arguments. In the example above, this is used to create a function. It could also be used to e.g. add such a function to a key map.

You can also quickly visit the the `.dir-locals.el` file with `C-c p E` (`M-x projectile-edit-dir-locals RET`).

Here are a few examples of how to use this feature with Projectile.

#### Configuring Projectile's Behavior

Projectile offers many customizable variables (via `defcustom`) that allows us to customize its behavior. Because of how `dir-locals.el` works, it can be used to set these customizations on a per-project basis.

You could enable caching for a project in this way:

    ((nil . ((projectile-enable-caching . t))))

If one of your projects had a file that you wanted Projectile to ignore, you would customize Projectile by:

    ((nil . ((projectile-globally-ignored-files . '("MyBinaryFile")))))

If you wanted to wrap the git command that Projectile uses to find list the files in you repository, you could do:

    ((nil . ((projectile-git-command . "/path/to/other/git ls-files -zco --exclude-standard"))))

If you want to use a different project name than how Projectile named your project, you could customize it with the following:

    ((nil . ((projectile-project-name . "your-project-name-here"))))

#### Configure a Project's Compilation, Test and Run commands

There are a few variables that are intended to be customized via `.dir-locals.el`.

- for compilation - `projectile-project-compilation-cmd`
- for testing - `projectile-project-test-cmd`
- for running - `projectile-project-run-cmd`

They're all set to `nil` by default, but by setting them you'll override the default commands per each supported project type. These variables can be strings to run external commands or Emacs Lisp functions:

    (setq projectile-test-cmd #'custom-test-function)

### Idle Timer

Projectile can be configured to run the hook `projectile-idle-timer-hook` every time Emacs is in a project and has been idle for `projectile-idle-timer-seconds` seconds (default is 30 seconds). To enable this feature, run:

    M-x customize-group RET projectile RET

and set `projectile-enable-idle-timer` to non-nil. By default, `projectile-idle-timer-hook` runs `projectile-regenerate-tags`. Add additional functions to the hook using `add-hook`:

    (add-hook 'projectile-idle-timer-hook 'my-projectile-idle-timer-function)

### Mode line indicator

By default the minor mode indicator of Projectile appears in the form " Projectile[ProjectName]". This is configurable via the custom variable `projectile-mode-line`, which expects a sexp like `'(:eval (format " Proj[%s]" (projectile-project-name)))`.

The project name will not appear by default when editing remote files (via TRAMP), as recalculating the project name (this is done on every keystroke) is a fairly slow operation there.