WriteLine

WriteLine[stream, "string"] writes "string", followed by a newline, to the specified output stream.

• WriteLine[proc, "string"] writes "string" to an external process proc.

Examples

stream = OpenWrite["test.txt"];
WriteLine[stream, "Hello World"];
Close[stream];

proc = StartProcess[$SystemShell];
WriteLine[proc, "echo hello"];

Please visit the official Wolfram Language Reference for more details.