Bash script to download file

Actions like reading data from files, working with loops, and swapping the values of two variables are good examples. The programmer will know at least one way to achieve their ends in a generic or vanilla fashion.

Perhaps that will suffice for the requirement at hand. But having the building-block idiom at their fingertips is a great starting point. Knowing and understanding idioms in one language makes it easier to pick up a new programming language, too.

In Bash, you can use a while loop on the command line to read each line of text from a file and do something with it. The while loop reads a line from the file, and the execution flow of the little program passes to the body of the loop. The echo command writes the line of text in the terminal window. The read attempt fails when there are no more lines to be read, and the loop is done. One neat trick is the ability to redirect a file into a loop. With Bash, you can simply use file redirection and let the shell handle all of that low-level stuff for you.

Linux already provides the cat command, which does exactly that for us. But it does visibly demonstrate the principles of reading from a file. That works well enough, up to a point. Suppose we have another text file that contains the names of the months. In this file, the escape sequence for a newline character has been appended to each line. Bash is interpreting the backslash as the start of an escape sequence.

It can be more convenient to read a line in its entirety—backslash escape sequences and all—and choose what to parse out or replace yourself, within your own code. We set a variable called Counter to zero, then we define our while loop. IFS stands for internal field separator.

For one, you only need to specify your parameters once and can reuse the script to set them on any host where you want them. Also, using a script makes sure the same parameters with the same values are set in the same way on every host where the script runs. There isn't just one way of doing it. I chose the following method because I believe it follows the "keep it simple" principle and has a pretty robust solution.

So here is the script, followed by an explanation:. The script starts with the shebang and some lines of comments. I like to use comments at the top to briefly describe what the script is supposed to do. Then I put in a debug switch with set -x. Try it out if you're not familiar with debugging. It comes in pretty handy when tracing errors in your script. I like to have all the variables I need to define in one place.

They are found in the next few lines following the comments and before I define some functions. You don't need to use functions, but I like them because they help give the script some structure.

And the functions help you when it comes to troubleshooting. For information, please read How to help GNU. If you'd like to get involved, it's a good idea to join the discussion mailing list see above.

We defend the rights of all software users. There are also other ways to contact the FSF. To demonstrate we have created a sample file named 'mycontent. Let's create a script named 'example1. We are thankful for your never ending support. Have a question or suggestion? Please leave a comment to start the discussion.

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