"The era of magnetic tapes" has not ended. It is just that some people mysteriously believe their data is safer "in the cloud" where they cannot monitor it, than on a tape in a fire safe under their own supervision. I have read back tapes I wrote myself 30 years earlier. Have you tried getting your data back from a deceased "cloud provider"?
That is why we get all these stories of ransomware attacks. Also, for many of us that have spent half a century learning Unix, we do not want our well proven tools snatched from our hands. There is room for more than one knife in a virtual tool box. On Sat, 11 Dec 2021 at 23:58, Stuart Longland <stua...@longlandclan.id.au> wrote: > On Sat, 11 Dec 2021 18:06:43 +0200 > <u...@mailo.com> wrote: > > > The Cult of DD > > Mar 17, 2017 > > You'll often see instructions for creating and using disk images on Unix > > systems making use of the dd command. This is a strange program of > > [obscure provenance](https://en.wikipedia.org/wiki/Dd_(Unix)) that > > somehow, still manages to survive in the 21st century. > > > > Actually, using dd is almost never necessary, and due to its highly > > nonstandard syntax is usually just an easy way to mess things up. For > > instance, you'll see instructions like this asking you to run commands > > like: > > > > […snip…] > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > End of article and my questions: > > > > Is the author right in general? > > Is the author right for Linux environment? > > Is the author right for OpenBSD environment? > > Can `cat`/`tail` et all, create a "sparse" file? > > vk4msl-gap$ dd if=/dev/zero bs=1M count=1 seek=9 of=sparsefile > > 1+0 records in > > 1+0 records out > > 1048576 bytes transferred in 0.009 secs (108639200 bytes/sec) > > vk4msl-gap$ ls -lh sparsefile > > -rw-r--r-- 1 stuartl stuartl 10.0M Dec 12 08:42 sparsefile > > vk4msl-gap$ du -hs sparsefile > > 1.0M sparsefile > > Very useful for "thin provisioning" of raw disk images with virtual > machines. > > Can `cat`/`tail` et all read bytes from the middle of a file? > > vk4msl-gap$ echo -n '000102030405060708090a0b0c0d0e0f' > test > > vk4msl-gap$ dd if=test of=test.part bs=2 skip=4 count=4 > > 4+0 records in > > 4+0 records out > > 8 bytes transferred in 0.000 secs (66541 bytes/sec) > > vk4msl-gap$ cat test.part > > 04050607 > > Can `cat`/`tail` et all overwrite specific bytes in the middle of a file? > > vk4msl-gap$ echo -n 'aaabacad' | dd of=test bs=2 count=4 seek=8 > conv=notrunc > > 4+0 records in > > 4+0 records out > > 8 bytes transferred in 0.000 secs (98985 bytes/sec) > > vk4msl-gap$ cat test > > 0001020304050607aaabacad0c0d0e0f > > I think you'll find `dd` was written in the era of magnetic tapes as a > storage medium, and so the ability to seek to a specific part of a tape > then perform a read or write, was seen as a critical feature of the day. > > That same feature is handy when doing various low-level disk operations > as well (e.g. backing-up/restoring the boot sector/partition table). > -- > Stuart Longland (aka Redhatter, VK4MSL) > > I haven't lost my mind... > ...it's backed up on a tape somewhere. > >
