The first and simplest utility of the VILLASnode toolbox is a signal generator. Rarely used in a real simulation, this tool can be handy for testing and understanding other commands of VILLASnode.

The following command emits a stream of samples to the standard output of your terminal:

$ villas signal -l 10 -r 10 -F 3 -v 1 sine

The samples have the following characteristics:

Option	Description
`-l 10`	Limits the output to 10 samples
`-r 10`	Samples the signal with a rate of 10 Hz
`-F 3`	Sets the frequency of the generated signal to 3 Hz
`-v 1`	Sets the number of values which are generated

Every sample is printed in a single line consisting of several columns:

# sec.nsec(seq)          data[]
1493840575.228483413(0)  0.000000
1493834176.992267295(1)  0.945584
1493834177.092542246(2) -0.605785
1493834177.192117703(3) -0.576049
1493834177.292412070(4)  0.957041
1493834177.391855814(5) -0.009495
1493834177.492009272(6) -0.947156
1493834177.592494371(7)  0.605067
1493834177.692448200(8)  0.570946
1493834177.791826929(9) -0.953784

The first column is a combination of timestamp and sequence number in the form of seconds.nanoseconds+offset(sequenceno). The timestamp is derived from Unix time (seconds after 01/01/1970 UTC). The remaining columns contain the values of the sample.

If you add the -n (non real-time mode) switch the data will be printed immeadiately to the screen:

$ villas signal -l 10 -r 10 -F 3 -v 1 -n sine

You can use shell redirection to write those samples to a file:

$ villas signal -l 10 -r 10 -F 3 -v 1 -n sine > file.dat

$ cat file.dat

Go to [lab 2] =>(node-lab-2)