Why Do I See an 'M' at the End of Lines in My Unix SQL Script?

'M' Character at End of Lines in SQL Script

When executing SQL scripts in Unix environments, users may encounter an unexpected 'M' character at the end of each line. This issue arises due to differences in line-ending characters between operating systems.

Unix-based systems use a single newline character (LF or n) to separate lines, while DOS/Windows systems employ a carriage return (CR or r) followed by a newline (LF or n). This results in the 'M' character (CR) being appended to the end of lines when scripts created on DOS/Windows are executed in Unix environments.

Solution: Convert Line Endings

To resolve this issue, convert the line endings of the SQL script to match the Unix format. This can be achieved using the dos2unix command:

dos2unix <script.sql>

This command replaces the CR LF line endings with LF line endings, ensuring compatibility with Unix environments.

Understanding Line-ending Conventions

It is important to be aware of different line-ending conventions when working with text files. The following table summarizes the common options:

Operating System	Line-ending Character
Unix, Linux	LF (n)
DOS, Windows	CR LF (rn)
MacOS (prior to Catalina)	CR (r)

By understanding these conventions and utilizing tools like dos2unix, you can effectively resolve issues related to line-ending differences.

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