You can type a long command in multiple lines in Linux/Unix shell by using backslash (). Suppose you have a long command to type in a small screen area then you can split that long command over multiple lines in Linux or Unix shell.
The following is the example to split long command in multiple lines in bash shell:
> target /
> catalog rman/admin@mydb1
> msglog=/home/oracle1/rmanlog/rmanlog01.log append
As you can see in above command that backslash is used to split the line followed by Enter key or Return key and when you press the enter key the line will be preceded by the > character, this shows that the command extended to the next line.