Working notes on Sh: Call a script, case, case example, Command-line arguments, Function, and If else, and related topics.
Topics
Call a script
Run a shell script with sh and optional positional arguments.
case
Shell case syntax matching values and running the matching statement.
case example
A case branch on TEST, including a default * pattern.
Command-line arguments
Positional parameters in a shell script, indexed from 1.
Function
Define a shell function, refer to $1 arguments, and call it. POSIX function keyword on dash.
If else
Shell if, elif, and else syntax, with numerical and string comparison operators.
Include
Source another shell file with . (alias for source).
Inline
Inline a command's output in a string with $(...).
Output to file and screen
Send stdout and stderr to both the screen and a file with tee -a.
Shebang
Portable bash shebang using env, and why sh is not bash.
String
Single quotes block variable expansion unless they sit inside double quotes.
