dd: split POSIX/BSD/GNU, sync pages, fix syntax (#9624)

* dd: split POSIX/BSD/GNU, sync pages, fix syntax

* Apply suggestions from code review

* Update dd.md

* Update dd.md

* Update dd.md

pages/linux/dd.md

@@ -0,0 +1,32 @@
+# dd
+
+> Convert and copy a file.
+> More information: <https://www.gnu.org/software/coreutils/dd>.
+
+- Make a bootable USB drive from an isohybrid file (such like `archlinux-xxx.iso`) and show the progress:
+
+`dd if={{path/to/file.iso}} of={{/dev/usb_drive}} status=progress`
+
+- Clone a drive to another drive with 4 MiB block, ignore error and show the progress:
+
+`dd if={{/dev/source_drive}} of={{/dev/dest_drive}} bs={{4M}} conv={{noerror}} status=progress`
+
+- Generate a file of 100 random bytes by using kernel random driver:
+
+`dd if=/dev/urandom of={{path/to/random_file}} bs={{100}} count={{1}}`
+
+- Benchmark the write performance of a disk:
+
+`dd if=/dev/zero of={{path/to/file_1GB}} bs={{1024}} count={{1000000}}`
+
+- Generate a system backup into an IMG file and show the progress:
+
+`dd if={{/dev/drive_device}} of={{path/to/file.img}} status=progress`
+
+- Restore a drive from an IMG file and show the progress:
+
+`dd if={{path/to/file.img}} of={{/dev/drive_device}} status=progress`
+
+- Check the progress of an ongoing dd operation (run this command from another shell):
+
+`kill -USR1 $(pgrep ^dd)`