Here is a simple script called command.sh:
#!/bin/bash echo \"I received: |$1|\"
When I call it with a line feed, it doesn\'t
Call your script as:
./command.sh 'foo > bar'
By placing \ before newline you're merely breaking current command line and not really passing newline character to your script.
\
If you want to do it in single line then use:
./command.sh $'foo\nbar'