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/dev/tcp

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  /dev/tcp Eli the Bearded <*@eli.users.panix.com> - 2026-08-19 21:20 +0000
    Re: /dev/tcp Richard Kettlewell <invalid@invalid.invalid> - 2026-08-19 23:53 +0100
    Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-19 23:42 +0000
      Re: /dev/tcp Eli the Bearded <*@eli.users.panix.com> - 2026-08-20 00:59 +0000
        Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-20 03:59 +0000
          Re: /dev/tcp Nuno Silva <nunojsilva@invalid.invalid> - 2026-08-20 10:10 +0100
          Re: /dev/tcp Eli the Bearded <*@eli.users.panix.com> - 2026-08-20 18:15 +0000
            Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-20 23:30 +0000
              Re: /dev/tcp Nuno Silva <nunojsilva@invalid.invalid> - 2026-08-21 01:18 +0100
              Re: /dev/tcp Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-08-21 09:52 +0200
                Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-21 08:12 +0000
                  Re: /dev/tcp Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-08-21 11:16 +0200
                    Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-21 22:57 +0000
                      Re: /dev/tcp Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-08-22 06:17 +0200
                Re: /dev/tcp c186282 <c186282@nnada.net> - 2026-08-21 21:50 -0400
              Re: /dev/tcp vallor <vallor@vallor.earth> - 2026-08-23 00:56 +0000
                Re: /dev/tcp Rich <rich@example.invalid> - 2026-08-23 04:01 +0000
                  Re: /dev/tcp c186282 <c186282@nnada.net> - 2026-08-23 03:37 -0400
    Re: /dev/tcp Rich <rich@example.invalid> - 2026-08-20 13:50 +0000
      Re: /dev/tcp c186282 <c186282@nnada.net> - 2026-08-20 13:02 -0400
        Re: /dev/tcp Rich <rich@example.invalid> - 2026-08-20 18:26 +0000
        Re: /dev/tcp The Natural Philosopher <tnp@invalid.invalid> - 2026-08-21 13:54 +0100
          Re: /dev/tcp c186282 <c186282@nnada.net> - 2026-08-21 22:57 -0400
            Re: /dev/tcp "Carlos E.R." <robin_listas@es.invalid> - 2026-08-22 21:47 +0200
              The hammer is best (Was: /dev/tcp) gazelle@shell.xmission.com (Kenny McCormack) - 2026-08-22 23:50 +0000
        Re: /dev/tcp Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2026-08-21 13:41 +0100
          Re: /dev/tcp Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-08-21 22:58 +0000
          Re: /dev/tcp c186282 <c186282@nnada.net> - 2026-08-21 22:28 -0400
      Re: /dev/tcp Eli the Bearded <*@eli.users.panix.com> - 2026-08-20 18:22 +0000
        Re: /dev/tcp The Natural Philosopher <tnp@invalid.invalid> - 2026-08-21 13:57 +0100

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#90227

c186282 <c186282@nnada.net> wrote:
>   Other odd Linux tricks - how many know you can
>   read/write to a disk drive that has no file
>   system ?

That is not a Linux trick, that's a Unix feature given that devices are 
mapped to files.

Just write your data to /dev/sda (whole disk, including boot sector) or 
/dev/sda5 (5th partition on disk).

That is where the 'dd' command is useful.  You can "clone" a disk on 
Unix (if you are root, or if the two disk device files have write 
permission for your current user) by just doing:

dd if=/dev/sda of=/dev/sdb bs=4096 

Assuming the disks use 4096 byte sectors.  

No need for extra "disk cloning" machines to actually duplicate a disk.

You can also backup the same way (although it is a rather wasteful way, 
as you also backup all the empty "free space" too):

dd if=/dev/sda of=/tmp/disk-backup bs=4096

None of this is new to anyone who's used, and understood from an admin 
perspective, a Unix system for any short length of time.

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#90281

On 20/08/2026 18:02, c186282 wrote:
> Other odd Linux tricks - how many know you can
>    read/write to a disk drive that has no file
>    system ?
Of course. Done all the time with floppies

Just write to the raw device.

After all, at some level some part of Linux has to do that anyway even 
if it is writing to a file.


-- 
"An intellectual is a person knowledgeable in one field who speaks out 
only in others...”

Tom Wolfe

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#90314

On 8/21/26 08:54, The Natural Philosopher wrote:
> On 20/08/2026 18:02, c186282 wrote:
>> Other odd Linux tricks - how many know you can
>>    read/write to a disk drive that has no file
>>    system ?
> Of course. Done all the time with floppies
> 
> Just write to the raw device.
> 
> After all, at some level some part of Linux has to do that anyway even 
> if it is writing to a file.

   It used to be popular for holding the max amount
   of binary data - no space wasted with the file
   system setup.

   A few years back I leveraged it for a disk-wipe
   program. Problem was that disks have become SO
   huge ... had to use M$ 128/256-bit var classes to
   access the whole thing.

   E-Disks ... can't REALLY wipe 'em alas. There
   are hidden buffers plus the wear-leveling scheme
   gets in the way. You wipe 'em the Hillary Clinton
   way - HAMMER  :-)

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#90353

On 2026-08-22 04:57, c186282 wrote:
> On 8/21/26 08:54, The Natural Philosopher wrote:
>> On 20/08/2026 18:02, c186282 wrote:
>>> Other odd Linux tricks - how many know you can
>>>    read/write to a disk drive that has no file
>>>    system ?
>> Of course. Done all the time with floppies
>>
>> Just write to the raw device.
>>
>> After all, at some level some part of Linux has to do that anyway even 
>> if it is writing to a file.
> 
>    It used to be popular for holding the max amount
>    of binary data - no space wasted with the file
>    system setup.
> 
>    A few years back I leveraged it for a disk-wipe
>    program. Problem was that disks have become SO
>    huge ... had to use M$ 128/256-bit var classes to
>    access the whole thing.
> 
>    E-Disks ... can't REALLY wipe 'em alas. There
>    are hidden buffers plus the wear-leveling scheme
>    gets in the way. You wipe 'em the Hillary Clinton
>    way - HAMMER  :-)

Instead, use encryption, on the device or the partitions.

-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;

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#90363 — The hammer is best (Was: /dev/tcp)

In article <fvaplmx3co.ln2@Telcontar.valinor>,
Carlos E.R. <robin_listas@es.invalid> wrote:
...
>>   are hidden buffers plus the wear-leveling scheme
>>   gets in the way. You wipe 'em the Hillary Clinton
>>   way - HAMMER :-)
>
>Instead, use encryption, on the device or the partitions.

Hammer is better, because encryption can be worked around by holding a gun
to the head of the person who knows the encryption key.

But a hammer is forever.

-- 
Trump has normalized hate.

The media has normalized Trump.

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#90284

c186282 wrote:

> On 8/20/26 09:50, Rich wrote:
>> 
>> These are handled by Bash, they don't exist as part of the OS (system).
> 
>    Correct. I've used the /dev/tcp trick before to
>    check ports. Seems to only work with Bash. Others
>    might add it eventually, but not too likely.

According to https://mywiki.wooledge.org/BashFAQ/061 the feature was
added to bash in version 2.04 and was "Copied from / Inspired by" ksh93.

It certainly works in the versions of ksh93 I have.

-- 
Geoff Clare <netnews@gclare.org.uk>

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#90303

On Fri, 21 Aug 2026 13:41:47 +0100, Geoff Clare wrote:

> According to https://mywiki.wooledge.org/BashFAQ/061 the feature was
> added to bash in version 2.04 and was "Copied from / Inspired by"
> ksh93.
>
> It certainly works in the versions of ksh93 I have.

Whatever happened to the idea of “do one thing, and do it well” ... ?

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#90313

On 8/21/26 08:41, Geoff Clare wrote:
> c186282 wrote:
> 
>> On 8/20/26 09:50, Rich wrote:
>>>
>>> These are handled by Bash, they don't exist as part of the OS (system).
>>
>>     Correct. I've used the /dev/tcp trick before to
>>     check ports. Seems to only work with Bash. Others
>>     might add it eventually, but not too likely.
> 
> According to https://mywiki.wooledge.org/BashFAQ/061 the feature was
> added to bash in version 2.04 and was "Copied from / Inspired by" ksh93.
> 
> It certainly works in the versions of ksh93 I have.

   You run ksh93 ???

   Not too many Kornies left these days :-)

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#90226

In comp.os.linux.misc, Rich  <rich@example.invalid> wrote:
> Eli the Bearded <*@eli.users.panix.com> wrote:
>> What system(s) have /dev/tcp/* natively?
> What "systems"?  Only those with a /bin/bash compiled with this 
> "special bash feature" compiled in.

None is a potential answer.

>>        Bash handles several filenames specially when they are used in
>>        redirections,  as described  in the  following table.   If the
                                                                  ^^^^^^
>>        operating  system on  which  bash is  running  provides  these
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>        special files, bash will use them;  other wise it will emulate
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>        them internally with the behavior described below.

> It's a Bash feature.  Note the man page quote you provided:
>>  **Bash** handles several filenames specially when they are used in 
>>  redirections

Note the underlined bit. In my mind "emulate" implies there is a thing
that does this, because the dictionary definition of "emulate" is very
close to "immitate".

From WordNet (r) 3.0 (2006) [wn]:
 
  emulate
      v 1: strive to equal or match, especially by imitating; "He is
           emulating the skating skills of his older sister"
      2: imitate the function of (another system), as by modifying the
         hardware or the software
      3: compete with successfully; approach or reach equality with;
         "This artist's drawings cannot emulate his water colors"

Note how there is nothing there about "make up whole cloth" or
"completely implement without reference to something else."

Elijah
------
realizes some documentation is fiction

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#90282

On 20/08/2026 19:22, Eli the Bearded wrote:
> Note the underlined bit. In my mind "emulate" implies there is a thing
> that does this, because the dictionary definition of "emulate" is very
> close to "imitate".

Emulation carries a strong implication of arriving at the same result by 
a radically different means, whereas imitate attempts to simply 
duplicate the method.
e.g. software models emulate the real world, they do not imitate it.



-- 
“It is hard to imagine a more stupid decision or more dangerous way of 
making decisions than by putting those decisions in the hands of people 
who pay no price for being wrong.”

Thomas Sowell

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