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May 27, 2017 18:59
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| #!/usr/bin/env bash | |
| #shellcheck disable=SC2034 | |
| # Comments prefixed by BASHDOC: are hints to specific GNU Bash Manual's section: | |
| # https://www.gnu.org/software/bash/manual/ | |
| ## Makes debuggers' life easier - Unofficial Bash Strict Mode | |
| ## http://redsymbol.net/articles/unofficial-bash-strict-mode/ | |
| ## BASHDOC: Shell Builtin Commands - Modifying Shell Behavior - The Set Builtin | |
| ### Exit prematurely if a command's return value is not 0(with some exceptions), triggers ERR trap if available. | |
| set -o errexit | |
| ### Trap on `ERR' is inherited by shell functions, command substitutions, and subshell environment as well | |
| set -o errtrace | |
| ### Exit prematurely if an unset variable is expanded, causing parameter expansion failure. | |
| set -o nounset | |
| ### Let the return value of a pipeline be the value of the last (rightmost) command to exit with a non-zero status | |
| set -o pipefail | |
| ## Non-overridable Primitive Variables | |
| ## | |
| ## BashFAQ/How do I determine the location of my script? I want to read some config files from the same place. - Greg's Wiki | |
| ## http://mywiki.wooledge.org/BashFAQ/028 | |
| RUNTIME_EXECUTABLE_FILENAME="$(basename "${BASH_SOURCE[0]}")" | |
| declare -r RUNTIME_EXECUTABLE_FILENAME | |
| declare -r RUNTIME_EXECUTABLE_NAME="${RUNTIME_EXECUTABLE_FILENAME%.*}" | |
| RUNTIME_EXECUTABLE_DIRECTORY="$(dirname "$(realpath --strip "${0}")")" | |
| declare -r RUNTIME_EXECUTABLE_DIRECTORY | |
| declare -r RUNTIME_EXECUTABLE_PATH_ABSOLUTE="${RUNTIME_EXECUTABLE_DIRECTORY}/${RUNTIME_EXECUTABLE_FILENAME}" | |
| declare -r RUNTIME_EXECUTABLE_PATH_RELATIVE="${0}" | |
| declare -r RUNTIME_COMMAND_BASE="${RUNTIME_COMMAND_BASE:-${0}}" | |
| ### These are the dependencies that are used later and also checked later | |
| declare -ar global_indexed_array=(1 2 3) | |
| declare -Ar global_associative_array=(\ | |
| ["apple"]="1" \ | |
| ["banana"]="2" \ | |
| ) | |
| trap_errexit(){ | |
| printf "An error occurred and the script is prematurely aborted\n" 1>&2 | |
| return 0 | |
| }; declare -fr trap_errexit; trap trap_errexit ERR | |
| trap_exit(){ | |
| return 0 | |
| }; declare -fr trap_exit; trap trap_exit EXIT | |
| is_set(){ | |
| declare -n array_nameref="${1}" | |
| if [ ! -v array_nameref ]; then | |
| return 1 | |
| else | |
| return 0 | |
| fi | |
| } | |
| ## init function: program entrypoint | |
| init(){ | |
| for parameter in global_associative_array global_indexed_array; do | |
| # Case: check in function | |
| if is_set "${parameter}"; then | |
| printf "%s is set\n" "${parameter}" | |
| else | |
| printf "%s is NOT set\n" "${parameter}" | |
| fi | |
| # Case: check inline | |
| declare -n array_nameref="${parameter}" | |
| if [ ! -v array_nameref ]; then | |
| printf "%s is NOT set\n" "${parameter}" | |
| else | |
| printf "%s is set\n" "${parameter}" | |
| fi | |
| unset -n array_nameref | |
| done | |
| # exit 0 | |
| }; declare -fr init | |
| init "${@}" |
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