Working with files

Opening files

Howl provides a text-oriented interface, and so you want see any traditional graphical open file dialogs. Instead you’ll open files from the command line, using commands. First off, the open command lets you navigate the file system and select a file to open. It’s bound to ctrl_o in the default keymap, and is also aliased as e for those more comfortable with VI. Triggering that command opens up the command line prompt and displays the contents of the current directory, as determined by the current buffer:

Once you’re in the prompt, you can then select the file of your choice. You can choose the file from the list by manually navigating using the arrow keys, ctrl_p, ctrl_n, etc., if you want. However, it’s usually much faster to narrow down the list by typing something that matches the file you want. Just as with completions (as described in the previous section), your input string will be matched against the available files using boundary matching or exact matching. Once the selected file ends up at top, simply press enter to open it.

If the file you selected is a directory, the list and prompt will update itself for the selected directory, letting you pick a file there. On the other hand, if you want to go up a directory level, press backspace. For convenience, if you type ~/ or / at the start of a prompt, you will be directly transferred to your home directory and the root directory respectively.

Opening a file within a project

Navigating the file system and selecting a file for opening is all fine and good for the odd file you want to open. Most of the time however, you’re likely working within the context of a project of some sort. In that case it can quickly get tedious to navigate directories up and down, and especially for larger projects, since you might not even be entirely sure where a desired file is placed. Fortunately, Howl offers the project-open command to help with this.

Howl provides simple and light-weight support for projects. In Howl, a project is currently defined as root directory containing the project files below, with an optional version control system attached to it. The project-open command (bound to ctrl_p by default) provides a way of selecting a file to open from all the files contained in your project. Thanks to the matching capabilities, this often provides a much faster way of opening files than navigating the project directory structure do. Below you’ll see an example for the Howl project itself:

Recursive file listings

When viewing the file listing for a directory within the open command, you can press ctrl_s to instantly switch to a recursive view. This shows all files within the directory tree rooted at the current directory allowing you to quickly find a file within that directory, or in any sub directory. This is somewhat similar to project-open, however it can be activated in any directory. To switch back to the regular, single level view, press ctrl_s again.

Saving buffers

Invoke the save command to save the current buffer to a file. If the buffer has an associated file, it will get saved to that file, and otherwise you’ll be prompted for the file name to save the buffer to. The save command is bound to ctrl_s in the default keymap, and is also aliased as w.

To save a buffer with an associated file to another file, invoke the save-as command (bound to ctrl_shift_s in the default keymap). There’s also a related command, save-and-quit, that allows you to save any modified buffers and exit Howl in one go.

Switching between open buffers

While Howl provides the ability to view more than one buffer at a time by supporting multiple open views, you’ll likely have more buffers open than you can fit on your screen. In order to switch to another buffer, you can use the switch-buffer command (bound to ctrl_b by default):

This let’s you select an open buffer to display in the current view. The list as presented is ordered by access time, thus you’ll see your most recent buffers at the top with less recently used buffers below. As always, you can type to narrow down the list.

Another command that might prove useful to you is switch-to-last-hidden-buffer. This will switch to the most recently accessed buffer that is not currently showing in any view, and is thus useful for quickly switching between to related files in the same view.

Creating new buffers / files

So what do you do if you just want to create a new buffer, that will eventually get saved to a new file? Well, there is a new-buffer command available for this, which will create a new buffer without an associated file, that you can later save to a named file. This is not bound to any key by default however, and the reason for that is that it’s not considered that useful. Most of the time when you want to create a new file, you already know what the file should be named. And as is the case with some other editors, such as Emacs or Vim, it is not a requirement for a file to actually exists in order to successfully open it. Thus, if you want to create a new file whose name you already know, just open the file using the open command and enter the new name of the file.

If this sounds strange to you, consider that a buffer and a file are two different entities, and that a buffer only has an association with a file. So when you open a non-existing file, you create a new buffer with an association to the specified file, which does not have to exist. As you save the buffer, the file will be created as necessary.

Closing buffers

Closing buffers is normally done with the buffer-close command. However, it’s quite easy to end up with a large number of open buffers unless you pay attention to closing old buffers as you’re done with them. Since many users might find other tasks more agreeable than pruning the list of buffers, Howl will attempt to automatically close old buffers for you. This is done by closing those buffers you haven’t bothered to look at for a while (assuming they’re not modified).

This behaviour is controlled by two configuration variables that you might want to tweak to better suit your editing preferences:

• cleanup_min_buffers_open

This specifies the minimum number of buffers that you want open at all times. Howl will never attempt to close buffers if you have less than this number of buffers open. The default is to keep at least 40 buffers open at any given time.

• cleanup_close_buffers_after

This specifies the amount of time, in hours, that should have passed since you last viewed a buffer before it should be considered eligible for closing. The default is 24 hours.

Next: Editing