eg:cat test.sh #!/bin/bash[ -e /etc/hosts ] && echo "ok" || echo "fail"bash test.sh okeg:cat test.sh #!/bin/bash[ -e /etc/hostssssss ] && echo "ok" || echo "fail"bash test.sh fail注意這里 && 必須在 || 之前

[ -f /home/tecmint/Downloads/xyz1.txt ] || {touch /home/tecmint/Downloads/xyz.txt; echo "The file does not exist"}“The file does not exist”