Use xxd to convert to hex

If you want to see the hex values of a file, the easiest way to do this is to use xxd.

Given foo.txt that contains “This is some text!”:

$ xxd foo.txt
00000000: 5468 6973 2069 7320 736f 6d65 2074 6578  This is some tex
00000010: 7421 0a                                  t!.

There are three columns in the output:

1. number of first character in hex
2. Hex representation of up to 16 bytes, separated every 2 bytes
3. ASCII representation, with a . for escape characters, like the 0A on the second line

There are some options that I find useful.

Firstly, we can use -u to get uppercase hex letters which I find more “normal”.

$ xxd -u foo.txt 
00000000: 5468 6973 2069 7320 736F 6D65 2074 6578  This is some tex
00000010: 7421 0A                                  t!.

More interestingly, -R always will colourise the output:

I particularly like how the colourised output has a different colour for the new line character so you can see that it isn’t a full stop (period for my US friends).

Lastly, -p will provide the plain dump style of just the hex characters:

$ xxd -u -p foo.txt 
5468697320697320736F6D652074657874210A

This is quite handy when you don’t need all the clutter.

All in all, xxd is a lovely tool when you need to find out exactly which characters are in a string.

The best bit though is this warning in the man page:

WARNINGS

The tool's weirdness matches its creator's brain. Use entirely at your own risk. Copy files. Trace it. Become a wizard.

What more is there to say?