curl does not interpret escape screens, so you need to insert the actual newline in the argument that curl sees. In other words, you must get a shell ( bash in this case) to interpret \n , or you need to insert a real new line.
The standard Posix shell does not interpret C escapes as \n , although the standard printf utility command does. However, bash provides a way to do this: in the form of a quote $'...' Resetting the backslash of C will be the interpreter. Otherwise, $'...' acts in the same way as '...' ; therefore, parameter and command replacements are not performed.
However, any shell, including bash , allows you to print newline characters inside quotation marks, and the newline is simply passed through as-is. Therefore, you can write:
curl -s \ -F "token=$TOKEN" \ -F "user=$USER" \ -F "message=Root Shell Access on $HOST $(date) $(who) " \ https://api.pushover.net/1/messages.json > /dev/null
(Note: I inserted parameter extensions when they seemed to be missing from the original curl command and changed the deprecated wildcards to the recommended form $(...) .)
The only problem with including newline literal lines, as mentioned above, is that it fills indentation if you care about appearance. Therefore, you can choose the form bash $'...' :
curl -s \ -F "token=$TOKEN" \ -F "user=$USER" \ -F "message=Root Shell Access on $HOST"$'\n'"$(date)"$'\n'"$(who)" \ https://api.pushover.net/1/messages.json > /dev/null
This is also a little difficult to read, but it is completely legal. The shell assumes that one argument (“word”) consists of any number of quoted or unquoted segments, if there are no spaces between the segments. But you can avoid the multiple-quote syntax by defining a variable that some people consider more readable:
NL=$'\n' curl -s \ -F "token=$TOKEN" \ -F "user=$USER" \ -F "message=Root Shell Access on $HOST$NL$(date)$NL$(who)" \ https://api.pushover.net/1/messages.json > /dev/null
Finally, you can use the standard printf utility if you are more used to this style:
curl -s \ -F "token=$TOKEN" \ -F "user=$USER" \ -F "$(printf "message=Root Shell Access on %s\n%s\n%s\n" \ "$HOST" "$(date)" "$(who)")" \ https://api.pushover.net/1/messages.json > /dev/null