path: root/README.md

# feh - Image Viewer and Cataloguer

**feh** is a light-weight, configurable and versatile image viewer.
It is aimed at command line users, but can also be started from graphical file
managers. Apart from viewing images, it can compile text and thumbnail
listings, show (un)loadable files, set X11 backgrounds, and more.

Features include filelists, various image sorting modes, custom action scripts,
and image captions. feh can be controlled by configurable keyboard and mouse
shortcuts, terminal input and signals.  When no file arguments or filelists are
specified, feh displays all files in the current directory.

This README focuses on installation and contribution instructions.  See the
[feh homepage](https://feh.finalrewind.org/) and the
[feh(1) manual](https://man.finalrewind.org/1/feh/) for other details.

## Dependencies

 * Imlib2
 * libcurl (disable with `curl=0`)
 * libpng
 * libX11
 * libXt
 * libXinerama (disable with `xinerama=0`)

Only when building with `exif=1`:

 * libexif-dev
 * libexif12

Only when building with `magic=1`:

 * libmagic

## Build Process

feh has been packaged for a variety of distributions, including
[Arch Linux](https://archlinux.org/packages/extra/x86_64/feh/),
[Debian](https://packages.debian.org/search?keywords=feh&exact=1),
[FreeBSD](https://www.freshports.org/graphics/feh), and
[Ubuntu](https://packages.ubuntu.com/search?keywords=feh&exact=1).
You can configure, compile and install a custom version as follows.

### Configuration

feh's build process uses make flags to enable/disable optional features and
fine-tune the build and installation process. It uses (hopefully) reasonable
defaults, so you can skip this section if you like.

Make flags can be passed as **make** arguments or set as environment variables,
like so:

```bash
$ make flag=bool
$ make install flag=bool
```
or
```bash
$ export flag=bool
$ make && make install
```

The following flags are respected by the makefile. A default value of **1**
indicates that the corresponding feature is enabled by default.

| Flag | Default value | Description |
| :--- | :---: | :--- |
| app  | 0 | install icons to /usr/share, regardless of `DESTDIR` and `PREFIX`, and call gtk-update-icon-cache afterwards |
| curl | 1 | use libcurl to view https:// and similar images |
| debug | 0 | debug build, enables `--debug` |
| exif | 0 | Builtin EXIF tag display support |
| help | 0 | include help text (refers to the manpage otherwise) |
| inotify | 0 | enable inotify, needed for `--auto-reload` |
| stat64 | 0 | Support CIFS shares from 64bit hosts on 32bit machines |
| magic | 0 | Use libmagic to filter unsupported file formats |
| mkstemps | 1 | Whether your libc provides `mkstemps()`. If set to 0, feh will be unable to load gif images via libcurl |
| verscmp | 1 | Whether your libc provides `strvercmp()`. If set to 0, feh will use an internal implementation. |
| xinerama | 1 | Support Xinerama/XRandR multiscreen setups |

For example, `make xinerama=0 debug=1` will disable Xinerama support and
produce a debug build; libcurl and natural sorting support will remain enabled.

Additionally, it supports the standard variables `CFLAGS`, `LDLIBS`, `PREFIX`,
and `DESTDIR`.

**PREFIX _(default: /usr/local)_** controls where the application and its data files
will be installed. It must be set both during `make` and `make install`.

**DESTDIR _(default: empty)_** sets the installation root during "make install". It
is mostly useful for package maintainers.

**Note:** Defaults are specified in `config.mk`. It is designed so that in most
cases, you can set environment variables instead of editing it. E.g.:

```bash
$ CFLAGS='-g -Os' make
```
```bash
$ export DESTDIR=/tmp/feh PREFIX=/usr
$ make && make install
```

Builtin EXIF support is maintained by Dennis Real, [here](https://github.com/reald/feh).

### Installation

Add your own make flags to the following examples as needed.

**For end users:**
```bash
$ make
$ sudo make install app=1
```

**For package maintainers and users who do not want feh to install its
icons into /usr/share:**
```bash
$ make
$ sudo make install
```

**Explanation:** feh ships some icons and an X11 desktop entry, which allow it to
be used from file managers, desktop menus and similar. However, installing
icons to /usr/local/share/... does not seem to work reliably.
Because of this, when using "make install app=1", feh will install its icons
to /usr/share/..., even though they technically belong into /usr/local.

[ZSH completion for
feh](https://git.finalrewind.org/zsh/plain/etc/completions/_feh) is also
available.

## Testing (non-X11)

The non-X11 parts of feh can be automatically tested by running

```bash
$ make test
```
This requires **perl >= 5.10** and the perl module `Test::Command`. Tests are
non-interactive and do not require a running X11, so they can safely be run on
a headless buildserver.

## Contributing

Bugfixes are always welcome, just open a pull request :)

Before proposing a new feature, please consider the scope of feh: It is an
image viewer and cataloguer, not an image editor or similar. Also, its option
list is already pretty long. Please discuss your ideas in a feature request
before opening a pull request in this case. Also, keep in mind that feh is
developed as a hobby project and that there is absolutely no obligation for
anyone to implement requested features or review merge requests.

Please keep in mind that feh's options, key bindings and format specifiers are
documented in two different places: The manual (man/feh.pre) and the help text
(src/help.raw). Although the help is not compiled in by default, it should be
kept up-to-date. On space-constrained embedded systems, it may be more useful
than the (significantly larger) man page.