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/osx/dd.md

@@ -1,20 +1,32 @@
 # dd
 
 > Convert and copy a file.
-> More information: <https://ss64.com/osx/dd.html>.
+> More information: <https://keith.github.io/xcode-man-pages/dd.1.html>.
 
-- Make a bootable USB drive from an isohybrid file (such like `archlinux-xxx.iso`):
+- Make a bootable USB drive from an isohybrid file (such like `archlinux-xxx.iso`) and show the progress:
 
-`dd if={{file.iso}} of=/dev/{{usb_drive}}`
+`dd if={{path/to/file.iso}} of={{/dev/usb_drive}} status=progress`
 
-- Clone a drive to another drive with 4 MB block and ignore error:
+- Clone a drive to another drive with 4 MB block, ignore error and show the progress:
 
-`dd if=/dev/{{source_drive}} of=/dev/{{dest_drive}} bs=4m conv=noerror`
+`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={{random_file}} bs=100 count=1`
+`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={{file_1GB}} bs=1024 count=1000000`
+`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)`