Once you have verified that the port connection works, you can write a simple C program for your Linux workstation to read from the Arduino:
/*
Simple read-only program for ttyUSB0 at 9600 bits/sec
Non-printing characters are shown in <hex>.
---davekw7x---
*/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
int main()
{
char *inname = "/dev/ttyUSB0";
int baud = 9600;
FILE *infile = fopen(inname, "r");
char inbuf[80];
/*
Instead of all of the "usual" stuff to set up
the input port, I'll just cheat with stty
*/
sprintf(inbuf, "stty -F %s %d raw", inname, baud);
system(inbuf);
if (!infile) {
fprintf(stderr, "Can't open %s for reading.\n", inname);
exit(EXIT_FAILURE);
}
printf("Opened %s for reading\n.", inname);
while (1) {
int inchar;
inchar = (unsigned int) getc(infile);
if (isprint(inchar)) {
printf("%c", inchar);
}
else {
printf("<%02x>", inchar);
if (inchar == '\n') {
printf("\n");
}
}
}
/* It's an infinite loop: Use ctrl-c to quit the program */
}
With this I get
.Hello from Arduino at 20<0d><0a>
Hello from Arduino at 1045<0d><0a>
Hello from Arduino at 2072<0d><0a>
Hello from Arduino at 3099<0d><0a>
Hello from Arduino at 4126<0d><0a>
Hello from Arduino at 5153<0d><0a>
Hello from Arduino at 6180<0d><0a>
.
. (Similar stuff until I hit Ctrl-C on the workstation)
.
I'm thinking that information for additional steps (for the workstation) beyond this would be for some place other than the "Arduino Syntax and Programs" board.
Bottom line: Once you have determined that the port can be configured to listen to the Arduino, the rest is "just software." (Famous last words.)
You can write a simple sketch to make the Arduino listen to the port and echo what it sees. Then you can write a simple C program to send something and see if it gets it back. Etc.
Then you may be ready to use OPC (you know, Other People's Code---that you copy from the Web) to do something more interesting. (Or, even more interesting: write your own code to do something even more interesting.)
Anyhow, here's a possible starting point.
Regards,
Dave
Footnote:
After you have been mucking around with the port, sometimes it is left in some state that the command-line stuff (like tail) doesn't give the same results unless you reset everything about the port. The "right" thing to do is not to use stty (in a program or from a command line), but stty may be the easiest way to get started. (By the "right" way, I mean to use low level open() instead of fopen() then use tcsetattr() and/or tcsetraw() to define specific port attributes and use read() to get the bytes. Stuff like that.)