add page for head in mac and linux

pages/linux/head.md

@@ -0,0 +1,19 @@
+# head
+
+> Output the first part of files
+
+- Output the first few lines of a file
+
+`head -n {{count of lines}} {{filename}}`
+
+- Output the first few bytes of a file
+
+`head -c {{size in kilobytes}} {{filename}}`
+
+- Output everything but the last few lines of a file
+
+`head -n -{{count of lines}} {{filename}}`
+
+- Output everything but the last few bytes of a file
+
+`head -c -{{size in kilobytes}} {{filename}}`