set options -xeuo

Commonly used options:

• -x: turns on debug output, logging each command as it is executed
• -e: causes the script to exit on most command failures (non-zero exit codes)
• -u: treats unset variables and parameters other than the special parameters @ or * as an error when performing parameter expansion
• -o pipefail: causes the script to exit if a command in a pipeline fails
• use a + to unset them if necessary

Many more options available: https://www.gnu.org/software/bash/manual/html_node/The-Set-Builtin.html

• $@ - All of the arguments as individual strings
• “$*” - All of the arguments as a single string
• $# - The number of arguments
• $1..n - Where n is an integer, the nth argument in the list
• $0 - The command name
• $? - The last exit code
• $IFS - Internal/input field separator (defaults to combo of space, newline and tab)

Declaring a function (needs to happen before use):

function <function_name> { … do things … }

- or -

<function_name>() { … do things … }

• Nothing ever goes inside parentheses.
• Passed parameters can be accessed with $1..$n.

• Use getopts to parse commandline options.