add dd.md for osx and linux

pages/linux/dd.md

@@ -0,0 +1,19 @@
+# dd
+
+> convert and copy a file
+
+- Make a bootable usb drive from an isohybrid file (such like archlinux-xxx.iso)
+
+`dd if={{file.iso}} of=/dev/{{usb_drive}}`
+
+- Clone a drive to another drive with 4MB block and ignore error
+
+`dd if=/dev/{{source_drive}} of=/dev/{{dest_drive}} bs=4M conv=noerror`
+
+- Generating a file of 100 random bytes by using kernel random driver
+
+`dd if=/dev/urandom of={{random_file}} bs=100 count=1`
+
+- Benchmark the write performance of a disk
+
+`dd if=/dev/zero of={{file_1GB}} bs=1024 count=1000000`

pages/osx/dd.md

@@ -0,0 +1,19 @@
+# dd
+
+> convert and copy a file
+
+- Make a bootable usb drive from an isohybrid file (such like archlinux-xxx.iso)
+
+`dd if={{file.iso}} of=/dev/{{usb_drive}}`
+
+- Clone a drive to another drive with 4MB block and ignore error
+
+`dd if=/dev/{{source_drive}} of=/dev/{{dest_drive}} bs=4m conv=noerror`
+
+- Generating a file of 100 random bytes by using kernel random driver
+
+`dd if=/dev/urandom of={{random_file}} bs=100 count=1`
+
+- Benchmark the write performance of a disk
+
+`dd if=/dev/zero of={{file_1GB}} bs=1024 count=1000000`