diff --git a/7/pcs/env.c b/7/pcs/env.c
new file mode 100644
index 0000000..faaf6a7
--- /dev/null
+++ b/7/pcs/env.c
@@ -0,0 +1,12 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+int main(void) {
+  char *pbuf = getenv("HOME");
+  printf("HOME: %s\n", pbuf);
+  
+  pbuf = getenv("LANG");
+  printf("LANG: %s\n", pbuf);
+
+  return 0;
+}
diff --git a/7/pcs/exit.c b/7/pcs/exit.c
new file mode 100644
index 0000000..ac05bf9
--- /dev/null
+++ b/7/pcs/exit.c
@@ -0,0 +1,17 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <limits.h>
+#include <unistd.h>
+
+void func(void) {
+  printf("calling func\n");
+}
+
+int main(void) {
+  printf("ATEXIT_MAX: %ld\n", sysconf(_SC_ATEXIT_MAX));
+  if(atexit(func)) {
+    printf("atexit error\n");
+    exit(-1);
+  }
+  exit(0);
+}
diff --git a/7/pcs/rlimit.c b/7/pcs/rlimit.c
new file mode 100644
index 0000000..710a91e
--- /dev/null
+++ b/7/pcs/rlimit.c
@@ -0,0 +1,47 @@
+#include <sys/resource.h>
+#include <stdio.h>
+
+int printRLimit(int resource) {
+  struct rlimit rlim;
+  if (getrlimit(resource, &rlim) < 0) {
+    printf("getrlimit error\n");
+    return -1;
+  }
+
+  if(rlim.rlim_cur != RLIM_INFINITY)
+    printf("CUR: %lu ", rlim.rlim_cur);
+  else
+    printf("CUR: (infinity) ");
+
+  if(rlim.rlim_max != RLIM_INFINITY)
+    printf("MAX: %lu ", rlim.rlim_max);
+  else
+    printf("MAX: (infinity) ");
+
+  printf("\n");
+
+  return 0;
+}
+
+int main(void) {
+
+  printRLimit(RLIMIT_AS);
+  printRLimit(RLIMIT_CPU);
+  printRLimit(RLIMIT_DATA);
+  printRLimit(RLIMIT_FSIZE);
+  printRLimit(RLIMIT_STACK);
+  printRLimit(RLIMIT_NPROC);
+  printRLimit(RLIMIT_NICE);
+
+  struct rlimit rlim;
+  rlim.rlim_cur = 1024;
+  rlim.rlim_max = 1024;
+
+  if(setrlimit(RLIMIT_STACK, &rlim) < 0) {
+    printf("setrlimit error\n");
+  }
+
+  printRLimit(RLIMIT_STACK);
+  
+  return 0;
+}