First functional version

xbrightness.c

@@ -0,0 +1,57 @@
+#include "xbrightness.h"
+
+void cmd(char *command, char *output) {
+    FILE *fp;
+
+    fp = popen(command, "r");
+    if (fp == NULL) {
+        output[0] = 0;
+    } else {
+        fgets(output, sizeof(output), fp);
+        pclose(fp);
+    }
+}
+
+float current() {
+    char out[1028];
+    cmd("xrandr --verbose | grep Brightness: | cut -f2 -d\" \"", out);
+    return strtof(out, NULL);
+}
+
+void set(float brightness) {
+    char screen[1028];
+    char command[1028] = "xrandr --output ";
+    char command2[] = " --brightness ";
+    char b[3];
+    cmd("xrandr | grep \" connected\" | cut -f1 -d\" \"", screen);
+    screen[strlen(screen)-1] = 0;
+    strcat(command, screen);
+    strcat(command, command2);
+    gcvt(brightness, 3, b);
+    strcat(command, b);
+    cmd(command, NULL);
+}
+
+int main(int argc, char **argv) {
+    if (argc == 1) {
+        printf("Current: %.2f\n", current());
+        return 0;
+    } else if (argc > 2) {
+        printf("Too many arguments !\n");
+        return 1;
+    }
+
+    char *entPrt;
+    float b = strtof(argv[1], &entPrt);
+    if (*entPrt != '\0') {
+        printf("Invalid brightness level !\n");
+        return 1;
+    } else {
+        if (argv[1][0] == '+' ||argv[1][0] == '-') {
+            set(current()+b);
+        } else {
+            set(b);
+        }
+    }
+    return 0;
+}

xbrightness.h

@@ -0,0 +1,8 @@
+#ifndef XBRIGHTNESS_H
+#define XBRIGHTNESS_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#endif