Error Handling

Error Action

1. errexit: terminates on any non-zero exit code $?

set -e # enable errexit

false # termination #

echo foo # unreachable

2. ${var:?ERROR}: throw ERROR when var is unset, terminates current execution.

set --
local foo="${1:?argument required}"

Value Fallback

If a variable is unset, there exist a way to fallback to another value inline.

set --
local foo="${1:-default value}"
# like foo ??= 'default value' in other lang
echo "$foo" # default value