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I know that it was possible to create blinking text, but did the operating system itself (I mean, in output from functions of COMMAND.COM and similar executables) ever make use of blink formatting?
You'd think it would be useful for confirmations of really dangerous things like format C: and such, but perhaps also seen as "over the top" and/or just not necessary.
Since the asker mentioned ‘similar executables’, I think it is fair to point to three applications, all bundled with MS-DOS 6.22:
FDISK:
Microsoft Diagnostics:
VSafe, an anti-virus TSR licensed by Microsoft from Central Point Software:
Those are the only examples that I know of. Blinking text was not frequently used perhaps less because it was considered ‘over the top’, but rather because most DOS applications (at least the bundled ones) were written against the terminal-style interrupt 0x21 I/O services, which did not expose capabilities like blinking text that are specific to PC video hardware. As we remember, the early versions of DOS did not only target PC-compatible hardware; relying on such features would harm DOS’s portability. As a bonus, those programs were able to be used with any terminal device that had DOS drivers; one could for example invoke the CTTY AUX command and later be able to interact with programs like FORMAT via a serial connection. TUI-style programs that accessed video hardware directly or via interrupt 0x10 calls (necessary to output blinking text) did not have this capability. But even the relatively few programs in the latter group usually had no reasonable use for blinking text.
One may argue that, for example, MSD shouldn’t count as ‘MS-DOS itself’, because it isn’t part of the ‘core’ MS-DOS; that, however, may be countered by saying that what deserves to be called a ‘core’ program is very much subjective anyway. The asker apparently considers FORMAT.COM a core utility, but it is very much possible to use DOS without formatting any disks; it isn’t strictly necessary. Not even COMMAND.COM is technically necessary to use DOS; a SHELL= setting in CONFIG.SYS can change the first loaded program to any other executable (say, DOS Shell), not even necessarily an actual shell. MSD is located on the second of the three MS-DOS 6.22 installation floppies, and the setup program will install it by default, so it can be considered just as much a part of the operating system as HIMEM.SYS.
FDISK.
Aug 24, 2020 at 8:54
[...] did the operating system itself [...] ever make use of blink formatting?
MS-DOS was, at the core, machine agnostic. It only used the most basic features provided by the BIOS. While INT 10h function 09h would have provided the ability to set attributes (via BL), its meaning already varies across video cards offered by IBM and even more so with third party cards or non IBM machines. Not to mention that MS-DOS was intended to work with terminals as well, where attributes are even more diverse.
MS-DOS only used the most basic characters for output control:
COMMAND.COM does check for ANSI.SYS and will use it if it’s available, e.g. for CLS.
Apr 18, 2019 at 11:35
IOCTL information for device 1, stdout, and then retrieves the interrupt vectors for 0x29 and 0x20, to determine whether CON is handled by the default device; if it’s not, it assumes there’s an ANSI driver.
Jan 17, 2021 at 15:11
Did MS DOS itself ever use blinking text?
What exactly does "itself" mean?
The OS kernel (io.sys or msdos.sys) would of course not do anything which is not requested by the currently running program (e.g. command.com); the kernel cannot know if some text message has the meaning: "Highly critical" or "Operation successful" so the request to change the text attributes must come from the program.
In MS-DOS consists of multiple programs. Most of them just wrote out text to the console while the text cursor was only moved implicitly because of printing the text.
However, there were also some "GUI-like" programs (fdisk, edit, GW or Q Basic, scandisk, the DOS-Shell and some backup program) being part of MS-DOS, which modified the content of the the entire text screen and explicitly moved the text cursor to certain positions.
As far as I know, the first type of programs (only printing text) never changed the text attributes. Neither color, nor blinking, nor bold. If the user selected blinking green text on blue background using ansi.sys (see supercat's comment), all of these programs would output all text green and blinking on blue background. If the user did not use ansi.sys, all text was gray, not blinking on black background.
The "GUI-like" programs used different screen attributes (such as different colors, bold or blinking). fdisk for example used bold text; edit used different colors. I'm not sure if one of these programs used blinking text.
fdisk) that did use blinking text as a warning to the user before erasing all data on-disk.
fxpark or fxprep.