Handling FIX Separators with an Alias

FIX Messages contain ASCII 1’s that tend to made casual analysis of them confusing. This post describes a simple way to create a command line alias to simplify reading FIX.

Argument for Translation

Without any update, FIX Message separators either don’t print (and fields all run together) or are shown with “^A”.

Here’s an example raw FIX Message:


If we translate the separator to a space, here’s the updated FIX Message:

8=FIX.4.2 9=121 35=D 49=buySide 56=broker 34=129 52=20100622-11:31:40 54=1 55=IBM 38=1000 44=20 40=2 11=Order1 21=2 60=20100622-03:10:39 10=064

Creating an Alias

The following commands expect use of the “bash” shell command line, natively available on Linux and Mac OS. However, Windows requires add-on packages to use “bash,” such as babun or cygwin.

Aliases are a command line shorthand to substitute a long command with a shorthand abbreviation. We can use this to translate the unprintable separators with white space or printable that improves readability.

alias fix="sed s/^A/\ /g"

NOTE: DO NOT cut & paste the above command! Cut and paste will not properly enter the ctrl-A (^A) character. It must by typed (ctrl-V, ctrl-A) as described in the previous section.

Type the command by hand and to enter the “^A” part of the above command, you need to enter ctrl-V followed by ctrl-A.

Making Aliases Permanent

You can make aliases available the next time you open a bash command line by adding the alias to shell startup file ~/.bashrc or ~/.bash_profile.

Put the above alias command at the end of the startup file. Next time you open a shell, that alias command will be read and set.

You can check this by opening a new shell and issuing this comment

alias fix

Which should give the following output (where the “^A” will NOT show up):

alias fix='sed s//\ /g'


You can now use this new alias to translate FIX Messages. For example:

fix abc.log | head -100

Would show you the first 100 lines from a file abc.log

Or you could copy the whole log with the separators translated:

fix abc.log > new_abc.log

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