Dynamically detect terminal size #634
Description
The simplest solution is to rely on the LINES and COLUMNS environment variables. (Update: these are bash variables and may not be available as env variables unless explicitly exported...)
- In bash, these are set if
shopt -s checkwinsizeis set. Apparently this is enabled by default. - In zsh, apparently these are set automatically
Alternatively (more advanced), the Lantern project (#633) shows how this can be done with ANSI escape sequences.
Example implementation to get the terminal size:
import java.io.IOException;
public class WinSize {
/*
/bin/stty -echo; /bin/stty -icanon; /bin/stty min 1; java WinSize; /bin/stty echo; /bin/stty icanon;
*/
public static void main(String... args) throws IOException {
String[] signals = new String[] {
"\u001b[s", // save cursor position
"\u001b[5000;5000H", // move to col 5000 row 5000
"\u001b[6n", // request cursor position
"\u001b[u", // restore cursor position
};
for (String s : signals) {
System.out.print(s);
}
int read = -1;
StringBuilder sb = new StringBuilder();
byte[] buff = new byte[1];
while ((read = System.in.read(buff, 0, 1)) != -1) {
sb.append((char) buff[0]);
//System.err.printf("Read %s chars, buf size=%s%n", read, sb.length());
if ('R' == buff[0]) {
break;
}
}
String size = sb.toString();
int rows = Integer.parseInt(size.substring(size.indexOf("\u001b[") + 2, size.indexOf(';')));
int cols = Integer.parseInt(size.substring(size.indexOf(';') + 1, size.indexOf('R')));
System.err.printf("rows = %s, cols = %s%n", rows, cols);
}
}