Use the Linux OD command

The OD (octal dump) and XD (hexdump) commands can display files or streams in decimal, octal, hexadecimal, and ASCII code, they are useful for accessing or visually checking characters in files that cannot be directly displayed on the terminal.
Syntax: OD [Option] file...
Meaning of each option in the command:
-A specifies the address base, including:
D decimal
O octal (default)
X hexadecimal
N do not print the displacement value
-T specifies the data display format. The main parameters include:
C ASCII character or backslash Sequence
D. Signed decimal number
F floating point number
O octal (the default value is 02)
U unsigned decimal number
X hexadecimal number
Other options except option C can be followed by a decimal number N, specifying the number of bytes contained in each display value.

Note: The default display mode of the OD command system is octal, which is also the origin of the command name (octal dump ). However, this is not the most useful display method. The combination of ASCII code and hexadecimal code can provide more valuable information output. Od-H file name