How can I dump a file of float values to the command-line?

Question

I have a file containing a raw sequence of 4-byte floating-point values - no headers, no formats, nothing else. I want to print some the float values in human-readable format, say from the n_1'th float to the n_2'th float, inclusive.

What's a simple way of doing this in a Unix-like command-line environment?

Answer 1

Use the octal dump utility, named od on Unix systems; it supports parsing floating-point binary representations as well.

Specifically, and letting N1 = n_1 * 4, N2 = n_2 * 4 and N3 = N2 - N1, invoke:

od -An -w4 -tf4 -j N1 -N N3 file_with_floats.bin

to get something like:

        -123.456
             inf
         111.222

for a file with three 4-byte float values.

Explanation:

• -w4 : Print the dumped values of 4 bytes per line (i.e. one float value)
• -An : No prefixing each line with the starting offset into the file
• -tf4 : Floating-point format, 4 bytes per value
• -j N1 : Skip N1 bytes
• -N N3 : Dump N3 bytes

If you want to print your file in C columns use 4*C as the argument to -w, e.g. -w20 will give you 5 columns per line.