fd - A simple file dumping tool

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TL;DR

fd reads files (or STDIN) as a sequence of (UTF-8) characters and dumps the content to STDOUT, thus the name fd. It does so in two columns, the left one will display the hex values of the bytes in the file, the right one will display the characters.

History

I created this tool back in 2004. It was programmed in a different world: On another operating system, using another file system (which most notably didn't have the concept of case-sensitive file names). This version originally used ISO-8859-1 as the default (and only) encoding, while it now assumes UTF-8.

The early versions had it easy: Each character was assumed to use one byte in the file. This made displaying it in rows with a constant number of characters easy. Nowadays, however, a singe character may be composed of a (varying) number of bytes, making it impossible to always display the same number of characters in each row. This is just a small aspect of how character encoding is more complicated (and more complex).

Installation

If you're using a Gemfile, add this line to make the tool available in your project:

gem 'fd'

Then execute:

    bundle install

Or install it yourself as:

gem install fd

Also see the fd page on rubygems.org

Usage

You can pass file names on the command line:

fd [-w number] [file_names]

For example (without colour highlighting of invisible characters):

> echo "Bacon ipsum dolor amet short ribs flank irure filet mignon brisket buffalo est porchetta." > some_file
>  ~/dev/fd ᚠ main > fd -w 7 some_file
some_file
42 61 63 6f 6e 20 69 | B a c o n ␠ i
70 73 75 6d 20 64 6f | p s u m ␠ d o
6c 6f 72 20 61 6d 65 | l o r ␠ a m e
74 20 73 68 6f 72 74 | t ␠ s h o r t
20 72 69 62 73 20 66 | ␠ r i b s ␠ f
6c 61 6e 6b 20 69 72 | l a n k ␠ i r
75 72 65 20 66 69 6c | u r e ␠ f i l
65 74 20 6d 69 67 6e | e t ␠ m i g n
6f 6e 20 62 72 69 73 | o n ␠ b r i s
6b 65 74 20 62 75 66 | k e t ␠ b u f
66 61 6c 6f 20 65 73 | f a l o ␠ e s
74 20 70 6f 72 63 68 | t ␠ p o r c h
   65 74 74 61 2e 0a |   e t t a . ␊

Here's a screenshot of a zsh session that shows the highlighting:

You can also pipe input from STDIN:

> echo "Put something into STDIN" | fd -w 5
STDIN
50 75 74 20 73 | P u t ␠ s
6f 6d 65 74 68 | o m e t h
69 6e 67 20 69 | i n g ␠ i
6e 74 6f 20 53 | n t o ␠ S
54 44 49 4e 0a | T D I N ␊

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/s2k/fd.

License

The gem is available under the terms of the MIT License.