스크립트 포멧 오류가 날 때 확인

The ^M is a carriage return character. Linux uses the line feed character to mark the end of a line, whereas Windows uses the two-character sequence CR LF. Your file has Windows line endings, which is confusing Linux.

Remove the spurious CR characters. You can do it with the following command:

sed -i -e 's/\r$//' custom_script.sh