added chgrp

src/chgrp.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <grp.h>
+#include <errno.h>
+#include <string.h>
+
+int
+main(int argc, char *argv[])
+{
+  if(argc == 1 || argc == 2)
+    {
+      fprintf(stderr,"usage: chgrp group file...\n");
+      return 1;
+    }
+  struct group *group_data = getgrnam(argv[1]);
+  gid_t gid = group_data->gr_gid;
+  for(int i = 2; i<argc; i++)
+    {
+      if(chown(argv[i],gid,getuid()) == -1)
+	fprintf(stderr,"error %i = %s\n",errno,strerror(errno));
+	
+    }
+
+}