The "sendOSC" Program

Matt Wright, revised 3/3/3

The program "sendOSC" is a text-based OpenSoundControl client. User can enter messages via command line arguments or standard input; sendOSC formats these messages according to the "OpenSoundControl" protocol, then sends the OpenSoundControl packet to an OpenSoundControl server via UDP or Unix protocol.


The "sendOSC" program is available as source code and as compiled binaries for Mac OS X. It has been tested under Linux, Mac OS X, and SGI IRIX.

Selecting a host machine and port number

usage: sendOSC [-h host] [-r] port_number [message...]

The "-h" flag indicates that the next argument is the name of the target host. The "-r" flag instructs sendOSC to look at the environment variable REMOTE_ADDR to get the name of the target host. The host can be either an Internet host name (e.g., "les") or an Internet address in standard dot notation (e.g., "")

If a target host is given, sendOSC uses the UDP protocol. Otherwise, the program uses the Unix protocol to connect to an OpenSoundControl server on the same machine.

The next command argument must be the port number.

For example, this invocation of sendOSC causes it to try to connect to host "rodet" on port 7009:

sendOSC -h rodet 7009

This invocation asks sendOSC to connect to port 7005 using the UNIX protocol:

sendOSC 7005

This invocation asks sendOSC to connect to port 7022 of host

sendOSC -r 7022

Command-Line Mode

If there are any additional command-line arguments after the port number, they're taken to be messages to be sent. In this mode, sendOSC reads all of the command line arguments, translates them into a OpenSoundControl packet, sends it in a single packet, and exits. sendOSC does not print any error or warning messages in this mode, which makes it a useful helper program for, e.g., CGI scripts.

Each command-line argument after the port number corresponds to an entire OpenSoundControl message, according to this comma-delimited format:


Each argument must be one of the following:

The messages are combined into a single UDP packet and sent atomically.

Example: The following Unix command sends the messages "/voices/0/tp/timbre_index 0", "/voices/0/tm/rate 1.0", and "/voices/0/tm/goto 0.0" to a server on port 7003 of the current machine:

sendOSC 7003 /voices/0/tp/timbre_index,0 /voices/0/tm/rate,1.0 /voices/0/tm/goto,0.0

Example: The following Unix command sends the messages "/voices/1/tp/timbre_index 3" and "load_file /usr/local/near/data/foo.format":

sendOSC 7003 /voices/1/tp/timbre_index,3 load_file,/usr/local/near/data/foo.format

Example: The following Unix command sends the message "/voices/2/tp/tone_bank 200. -19. 300. -32. 400. -40.":

sendOSC 7003 /voices/2/tp/tone_bank,200.,-19.,300.,-32.,400.,-40.

Remember that the Unix shell will interpret any whitespace characters (space, tab, etc.) as delimiting the arguments to sendOSC. So if you want your string arguments to include any space characters, you must quote them to the shell. For example, these equivalent commands send the message "string_message" with the argument string "this string has spaces":

sendOSC 7003 "string_message,this string has spaces"
sendOSC 7003 string_message,this\ string\ has\ spaces

There are other characters which are special to Unix shells: "!", "$", ";", "~", etc. Be careful.

Interactive Mode

If the port number is the last command-line argument, sendOSC enters an interactive mode. In this mode, lines of stdin should look like this:

message_name arg1 arg2 arg3...

Each line of stdin is converted into a one-message OpenSoundControl packet and sent immediately.


sendOSC 7003
message1 2.0 3.14159
message2 100 200 300
message3 string1 string_number_two /the/third/string
message4 1 2.0 three

In this interactive mode, any whitespace character is interpreted as delimiting the arguments to a message. To include whitespace in a string, surround the entire string with double-quote characters. Example:

sendOSC 7003
stringmessage "This string has spaces in it"

To exit interactive mode and return to the shell, type an EOF (control-D) or interrupt (control-C). The sendOSC program will also quit if it is unable to send a packet, i.e., if you don't have a server listening on the machine and port that sendOSC is trying to send to.

Constructing Multiple-Message Bundles

To bundle multiple messages into the same packet while in interactive mode, begin by entering an open bracket character ("[") by itself on a line. Once you've done this, all of the lines you enter will be accumulated into a large OpenSoundControl bundle until you enter a close bracket character ("]") by itself on a line, at which point the entire packet will be sent.


sendOSC 7003
/voices/0/tp/timbre_index 7.0
/voices/0/tm/rate 1.0
/voices/0/tm/goto 0.0

These bracketed bundles can be nested.

Blank Lines

If you enter a blank line in the middle of constructing a message group with [ and ], it is ignored. Otherwise, if you enter a blank line, sendOSC re-sends the previous packet, which may be a single message or a group of messages.

The "play" Hack

To save typing, if you enter "play" by itself on an empty line, it's equivalent to the following:

/voices/0/tp/timbre_index 0
/voices/0/tm/goto 0.0

Sending Time Tags

The OpenSound Control protocol includes space for a 8-byte time tag in each bundle. By default, sendOSC uses the value 1, meaning "do it immediately" as the time tag for every bundle. But you can put a time tag into a bundle by typing some stuff after the open bracket character that opens the bundle. There are two ways to do this.

If you have a hexadecimal number after the open bracket character, it will be used as the time tag. Since OSC time tags are 8 bytes, you can have up to 16 hex digits.

If you have a plus sign and then a (decimal) number after the open bracket character, the number will be interpreted as a number of seconds into the future, which will be added to the computer's notion of the current time to produce the time tag. (This feature is currently available only on the SGI version of sendOSC.)

Exit Status Codes

sendOSC sets the Unix exit status to indicate whether or not it was successful. In interactive mode, sendOSC also prints warning and error messages to the screen, so the exit status is not so crucial. In command line mode, however, the exit status is the only way to know if sendOSC could do its job.

Here are the possible exit status codes:

0: Successful

2: Message(s) were dropped because of buffer overflow.

3: Socket error

4: Usage error: incorrect command-line arguments, or a "-r" without REMOTE_ADDR defined.

5: Internal error: this should never occur.