Add line break to 'git commit -m' from the command line
Certainly, how it's done depends on your shell. In Bash, you can use single quotes around the message and can just leave the quote open, which will make Bash prompt for another line, until you close the quote. Like this:
git commit -m 'Messagegoeshere'
Alternatively, you can use a "here document" (also known as heredoc):
git commit -F- <<EOFMessagegoeshereEOF