Moor is a pager. It reads and displays UTF-8 encoded text from files or pipelines.

moor is designed to just do the right thing without any configuration:

The intention is that Moor should be trivial to get into if you have previously been using Less. If you come from Less and find Moor confusing or hard to migrate to, please report it!

Doing the right thing includes:

• Syntax highlight source code by default using Chroma
• Search is incremental / find-as-you-type just like in Chrome or Emacs
• Filtering is incremental: Press & to filter the input interactively
• Search becomes case sensitive if you add any UPPER CASE characters to your search terms, just like in Emacs
• Regexp search if your search string is a valid regexp
• Snappy UI even on slow / large input by reading input in the background and using multi-threaded search
• Supports displaying ANSI color coded texts (like the output from git diff | riff for example)
• Supports UTF-8 input and output
• Transparent decompression when viewing compressed text files (.gz, .bz2, .xz, .zst, .zstd) or streams
• The position in the file is always shown
• Supports word wrapping (on actual word boundaries) if requested using --wrap or by pressing w
• Follows output as long as you are on the last line, just like tail -f
• Renders terminal hyperlinks properly
• Mouse Scrolling works out of the box (but look here for tradeoffs)

For compatibility reasons, moor uses the formats declared in these environment variables if present:

• LESS_TERMCAP_md: Man page bold
• LESS_TERMCAP_us: Man page underline
• LESS_TERMCAP_so: Status bar and search hits

For configurability reasons, moor reads extra command line options from the MOOR environment variable.

Moor is used as the default pager by:

• px / ptop, ps and top for human beings
• riff, a diff filter highlighting which line parts have changed

Installing

Using Homebrew

⚠️ Installs legacy moar binary.

Both macOS and Linux users can use Homebrew to install. See below for distro specific instructions.

brew install moar

Then whenever you want to upgrade to the latest release:

brew upgrade

Using MacPorts

⚠️ Installs legacy moar binary.

sudo port install moar

More info here.

Using Gentoo

⚠️ Installs legacy moar binary.

emerge --ask --verbose sys-apps/moar

More info here.

Using Arch Linux

⚠️ Installs legacy moar binary.

yay -S moar

More info here.

Debian / Ubuntu

Nobody has stepped up to maintain moor for Debian.

If you want to maintain the moor packaging for Debian, that would be very welcome!

Otherwise use Homebrew (see above) or read on for manual install instructions.

Manual Install

Using go

This will install moor into $GOPATH/bin :

go install github.com/walles/moor@latest

NOTE: If you got here because there is no binary for your platform, please consider packaging moor.

Downloading binaries

1. Download moor for your platform from https://github.com/walles/moor/releases/latest
2. chmod a+x moor-*-*-*
3. sudo mv moor-*-*-* /usr/local/bin/moor

And now you can just invoke moor from the prompt!

Try moor --help to see options.

Configuring

Do moor --help for an up to date list of options.

Environment variable MOOR can be used to set default options.

For example:

export MOOR='--statusbar=bold --no-linenumbers'

Setting moor as your default pager

Set it as your default pager by adding...

export PAGER=/usr/local/bin/moor

... to your .bashrc.

Issues

Issues are tracked here, or you can send questions to johan.walles@gmail.com.

Packaging

If you package moor, do include the man page in your package.

Embedding

Here's one way to embed moor in your app:

package main

import (
	"github.com/walles/moor/pkg/moor"
)

func main() {
	err := moor.PageFromString("Hello, world!", moor.Options{})
	if err != nil {
		// Handle paging problems
		panic(err)
	}
}

You can also PageFromStream() or PageFromFile().

Developing

You need the go tools.

Run tests:

./test.sh

Launch the manual test suite:

./manual-test.sh

To run tests in 32 bit mode, either do GOARCH=386 ./test.sh if you're on Linux, or docker build . -f Dockerfile-test-386 (tested on macOS).

Run microbenchmarks:

go test -benchmem -run='^$' -bench=. ./...

Profiling BenchmarkPlainTextSearch(). Try replacing -alloc_objects with -alloc_space or change the -focus function:

go test -memprofilerate 1 -memprofile profile.out -benchmem -run='^$' -bench '^BenchmarkPlainTextSearch$' github.com/walles/moor/internal && go tool pprof -alloc_objects -focus findFirstHit -relative_percentages -web profile.out

Build + run:

./moor.sh ...

Install (into /usr/local/bin) from source:

./install.sh

Making a new Release

Make sure that screenshot.png matches moor's current UI. If it doesn't, scale a window to 81x16 characters and make a new one.

Execute release.sh and follow instructions.

TODO

• Enable exiting using ^c (without restoring the screen).

• Start at a certain line if run as moor file.txt:42

• Handle search hits to the right of the right screen edge. Searching forwards should move first right, then to the left edge and down. Searching backwards should move first left, then up and to the right edge (if needed for showing search hits).

• Support viewing multiple files by pushing them in reverse order on the view stack.

• Retain the search string when pressing / to search a second time.

Done

• Add > markers at the end of lines being cut because they are too long

• Doing moor on an arbitrary binary (like /bin/ls) should put all line-continuation markers at the rightmost column. This really means our truncation code must work even with things like tabs and various control characters.

• Make sure search hits are highlighted even when we have to scroll right to see them

• Change out-of-file visualization to writing --- after the end of the file and leaving the rest of the screen blank.

• Exit search on pressing up / down / pageup / pagedown keys and scroll. I attempted to do that spontaneously, so it's probably a good idea.

• Remedy all FIXMEs in this README file

• Release the go version as the new moor, replacing the previous Ruby implementation

• Add licensing information (same as for the Ruby branch)

• Make sure git grep output gets highlighted properly.

• Handle all kinds of line endings.

• Make sure version information is printed if there are warnings.

• Add spinners while file is still loading

• Make tail -f /dev/null exit properly, fix #7.

• Showing unicode search hits should highlight the correct chars

• Word wrap text rather than character wrap it.

• Arrow keys up / down while in line wrapping mode should scroll by screen line, not by input file line.

• Define 'g' to prompt for a line number to go to.