SHELL

return boolean bash

#!/bin/bash
isdirectory() {
  if [ -d "$1" ]
  then
    true
  else
    false
  fi
}

if isdirectory $1; then echo "is directory"; else echo "nopes"; fi

boolean in shell script

my_bool=true

if [ "$my_bool" = true ]; then
if [ "$my_bool" = "true" ]; then

if [[ "$my_bool" = true ]]; then
if [[ "$my_bool" = "true" ]]; then
if [[ "$my_bool" == true ]]; then
if [[ "$my_bool" == "true" ]]; then

if test "$my_bool" = true; then
if test "$my_bool" = "true"; then