How do I use awk pattern scanning and processing language under bash scripts? Can you provide a few examples?
Awk is an excellent tool for building UNIX/Linux shell scripts. AWK is a programming language that is designed for processing text-based data, either in files or data streams, or using shell pipes. In other words you can [...]

need to count one character at a time from input.txt. How do I read one character at a time under Linux / UNIX bash shell script?
The read builtin can read one character at a time and syntax is as follows:
 
read -n 1 c
echo $c
 
You can setup the while loop as follows:
#!/bin/bash
# data file
INPUT=/path/to/input.txt
 
# while loop
while IFS= [...]