Shell

Start at 01. The first lesson names the types. The next one builds an object. Each sample is on the page.

1. Skill

   Basics

   The types, explained, then an object you can name and call.

   1. 01 Shell from zero: a variable holds text Start here

      A shell variable holds text. item=latte stores latte, and echo prints it. There are no spaces around the equals sign.

      Adds The types this course uses

      2 min read

   2. 02 Shell from zero: quote the expansion

      A value with a space splits into two words if you leave the quotes off. "$name" keeps it one value. The program prints oat latte.

      Adds An object you can name and call

      Builds on 12 min read

2. Practice

   Tips

   A rule that prevents a bug, then a program that uses the object.

   1. 03 Shell from zero: a number is still text until you ask

      A variable that looks like a number is text. $((cents * 2)) evaluates it as arithmetic. The program stores 450 and prints 900.

      Adds A tip that prevents a bug

      Builds on 1 through 22 min read

   2. 04 Shell from zero: a function is the reusable piece

      A function packages a command you want to repeat. label prints a drink and its price. The program prints latte $4.50.

      Adds A program that uses the object

      Builds on 1 through 32 min read

3. Further

   A whole program

   One more idea, then a program that puts the pieces together.

   1. 05 Shell from zero: local keeps the name inside

      local makes a variable private to the function. The function prints muffin. The script then prints latte. The caller's drink is unchanged.

      Adds A program that puts the pieces together

      Builds on 1 through 42 min read

   2. 06 Shell from zero: read the exit code

      A command returns a number when it finishes. 0 means it worked. An empty drink name fails test -n. The program prints 1. Check the code before you trust the result.

      Adds A program that puts the pieces together

      Builds on 1 through 52 min read