Formatting your data/output using echo and printf

Sometimes, finding the string or the exact data you are looking for is the easy part of your task, but formatting the output data is tricky. For example, here are some situations that have subtle elements that need to be altered:

• Echoing output without the newline terminator (\n)
• Echoing raw hexadecimal (hex) data
• Printing raw hexadecimal values and printable ASCII characters
• Concatenating strings
• Escaping specific characters
• Aligning text
• Printing horizontal rules

In addition to tricks, we can also print values to the screen that are also floats as well (in addition to the recipe for math). Wait, what is a hexadecimal number? Yes, another type of data or at least a representation exists. To understand what hexadecimals are, we first need to remember that computers use binary, which consists of 1s and 0s (ones and zeros). However, binary is not very friendly to us humans (we use the decimal format when looking at numbers typically), so other representations are sometimes needed, one of which is called hexadecimal. As you have probably guessed, it is base 16 so it looks like 0x0 to 0xF (0x0,0x1, ... ,0x9,0xA,0xB, ..., 0XF). Here is an example:

$ echo -en '\xF0\x9F\x92\x80\n'

$ printf '\xF0\x9F\x92\x80\n'

In the preceding example, both printf and echo can be used to print raw hex and Unicode characters. Using a Unicode reference, I found the UTF-8 encoding for the skull character (F0 9F 92 80) and then formatted it using \xFF. Notice where FF is; it is in each byte.

Wait, another term called a byte? Yes, and here is another one called a bit. A bit is the form because it refers to either a 0 or 1, but a byte is 8 bits (one byte is made up of eight bits! Get it?).

However, we are getting a bit ahead of ourselves—what is echo and printf? Both are commands which you may have seen earlier in this cookbook that allow you to output the contents of variables and more to the console or even to a file. Echo is far more "straightforward", but printf can provide the same and more functionality using C style parameters. In fact, one of the main features of printf over echo is that printf can format characters, pad them, and even align them.

Alright; let's get to work.