Writing a bash script to run a java program with command line arguments?

Question

I have written a java program that maintains a database for bank accounts (This is a course assignment) and I want to create a bash script to run. Upon running the program, you have to input "i", "h", "t" or "?" to get it to perform a task. I would like to take those command line arguments and use them for when running this program in bash. For example, if the script were named accounts, I want to be able to type accounts -i and the script would launch the program with the i command already input and perform the task for that argument? How would I go about doing that?

Answer 1

The best would properly be for your Java program to take arguments.

But I assume all of this is for educational purpose only, and that said Java program reads from standard input.

Usually configuration for a program should go as arguments:

$ ./my_program --configA --configB --optC=valD

But In your case it seems like you have an interactive program that prompts the user for questions:

$ ./my_program
Question 1?
> Answer1
Question 2?
> Answer2

$ is command prompt, and > is user input.

Anyway one can feed standard input from a pipe, file, etc etc:

my_program1 | my_program2

Output from my_program1 goes as input to my_program2.

my_program < my_file

Input to my_program is coming from a file my_file.

You can also feed input from a here documents, the syntax is <<MARKER and ends with MARKER:

my_program << NAME_DOESNT_MATTER
line1
line2
line3
NAME_DOESNT_MATTER

This will put three lines into my_program.

In bash it's simply to refer to positional parameters as they are called $1, $2, .. $n:

$ cat my_shell_program
#!/bin/bash
echo "$2" "$1"
$ ./my_shell_program "hello world" "John Doe"
John Doe hello world

Now you should be able to figure out the rest.