When did Windows start accepting forward slash as a path separator?

**Ben Finney** · Jul 18 '05, 02:58 AM

Re: When did Windows start accepting forward slash as a path separator?

On 25 Sep 2003 16:50:49 -0700, Stephen Ferg wrote:[color=blue]
> But now, among a small group of cognoscenti, it is a truism that this
> is a myth, and that Windows will allow you to use either the forward
> or the backward slash as a pathname separator.[/color]

I highly doubt it, since the forward slash (or just "slash") is the
conventional Windows command-line option indicator, analogous to the
hyphen on Unix. To accept it as the start of a filename would break
zillions of existing systems, for no appreciable benefit to Microsoft.

Python automagically determines the path component separator, os.sep,
and uses it for most file path transformations to and from the internal
language's '/'.

<http://www.python.org/doc/2.3.1/lib/os-path.html#l2h-1552>

Is this perhaps what gives you the impression?

--
\ "I went to a restaurant that serves 'breakfast at any time'. So |
`\ I ordered French Toast during the Renaissance." -- Steven |
_o__) Wright |
Ben Finney <http://bignose.squidly .org/>

**Bob Gailer** · Jul 18 '05, 02:58 AM

Re: When did Windows start accepting forward slash as a pathseparator?

At 05:50 PM 9/25/2003, Stephen Ferg wrote:
[color=blue]
>I have a question that is not directly Python-related. But I thought
>I'd ask the most erudite group that I know... :-)
>
>When did Windows start accepting the forward slash as a path separator
>character?[/color]

Good question. Certainly later than:

Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.

C:\>cd /samis
The syntax of the command is incorrect.

Bob Gailer
bgailer@alum.rp i.edu
303 442 2625

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.506 / Virus Database: 303 - Release Date: 8/1/2003

**Andrew Dalke** · Jul 18 '05, 02:58 AM

Re: When did Windows start accepting forward slash as a path separator?

Stephen Ferg:[color=blue]
> When did Windows start accepting the forward slash as a path separator
> character?[/color]

DOS 2. When directories were introduced. Many of the functions
were based on unix, down to a NUL terminated filename and the
name "creat".

But DOS 1 was modelled on CP/M which used "/" as a command
line option flag. You couldn't use a "/" in the DOS shell because
it would be interpreted as the flag. You could change the flag using
a DOS command, eg, to use "-" instead, but that was disabled in
the 3.x days; for good reason.

Hence, the low-level DOS commands (since 2.0) would take
both / and \ as separators, but some codes did their own
filename munging and would not.
[color=blue]
> At one time, it was accepted as a truism that Windows (like MS-DOS)
> was different from Unix because Windows used the backslash as the path
> separator character, whereas Unix used the forward slash.[/color]

It was? My copy of Norton's Guide to the IBM PC makes
the explicit statement that directories were directly influenced by
unix. I actually regard this as a point of similarity. The character
used is a minor issue.

There are, of course, many ways in which they are different. Like
drive names, which comes from CP/M, and the filesystem layout
itself (FAT vs. inodes). And DOS had much better IDEs, like
Turbo Pascal. ;)
[color=blue]
> I hypothesize that originally Windows accepted only the backslash, and
> then at some time it changed to accept the forward slash as well.
> Does anyone know when that change occurred? Was it with the
> introduction of support for long filenames in NT and Win95?[/color]

The original Windows was a shell on top of DOS. Programs
under Windows could use the DOS layer directly, which took
both separators. Even in Wn95 I could exit to DOS, meaning
I could quite out of Win95 to the shell prompt then do 'win'
to start it up again.

Andrew
dalke@dalkescie ntific.com

**Michael Geary** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Stephen Ferg wrote:[color=blue]
> When did Windows start accepting the forward slash as a path separator
> character?
>
> At one time, it was accepted as a truism that Windows (like MS-DOS)
> was different from Unix because Windows used the backslash as the path
> separator character, whereas Unix used the forward slash.
>
> But now, among a small group of cognoscenti, it is a truism that this
> is a myth, and that Windows will allow you to use either the forward
> or the backward slash as a pathname separator.
>
> I hypothesize that originally Windows accepted only the backslash, and
> then at some time it changed to accept the forward slash as well.
> Does anyone know when that change occurred? Was it with the
> introduction of support for long filenames in NT and Win95?[/color]

Hi Steve,

Every version of Windows has accepted "/" as a path separator. So has every
version of MS-DOS beginning with DOS 2.0 (the first version that had
subdirectories) .

It's only been in command lines that "/" was not allowed, because it had
already been used as a switch delimiter in MS-DOS 1.0.

-Mike

**Michael Geary** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

> Stephen Ferg wrote:[color=blue][color=green]
> > But now, among a small group of cognoscenti, it is a truism that this
> > is a myth, and that Windows will allow you to use either the forward
> > or the backward slash as a pathname separator.[/color][/color]

Ben Finney wrote:[color=blue]
> I highly doubt it, since the forward slash (or just "slash") is the
> conventional Windows command-line option indicator, analogous to the
> hyphen on Unix. To accept it as the start of a filename would break
> zillions of existing systems, for no appreciable benefit to Microsoft.[/color]

Actually, every version of Windows, and every version of MS-DOS from 2.0 on,
has accepted "/" as a path delimiter.

Don't confuse the command line with the Windows or DOS kernel. Most command
lines don't allow "/" because it conflicts with the use of "/" for a switch
deliminer. But the Windows and DOS kernels are happy with either "\" or "/".

-Mike

**Andrew Dalke** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Bob Gailer:[color=blue]
> Good question. Certainly later than:
>
> Microsoft Windows 2000 [Version 5.00.2195]
> (C) Copyright 1985-2000 Microsoft Corp.
>
> C:\>cd /samis
> The syntax of the command is incorrect.[/color]

The shell is parsing the line and interprets the "/" as a
command-line flag, Try a relative path, like

cd ./samis

Andrew
dalke@dalkescie ntific.com

**Grant Edwards** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

In article <b16e4ef7.03092 51550.724a57f@p osting.google.c om>, Stephen Ferg wrote:
[color=blue]
> When did Windows start accepting the forward slash as a path separator
> character?[/color]

Sometime prior to 1983. DOS has always accepted it, and I assume Windows
always has as well.
[color=blue]
> At one time, it was accepted as a truism that Windows (like MS-DOS)
> was different from Unix because Windows used the backslash as the path
> separator character,[/color]

Accepted as a truism by whom? DOS would accept either. The shell's "switch"
character was configurable as well -- it defaulted to '/' but changing it to
'-' was trivial.
[color=blue]
> whereas Unix used the forward slash.[/color]
[color=blue]
> But now, among a small group of cognoscenti, it is a truism that this
> is a myth, and that Windows will allow you to use either the forward
> or the backward slash as a pathname separator.[/color]

I don't remember if the actual DOS system calls accepted '/' or if the C
library translated. I do know that DOS C programs could use '/' for path
separator at least 20 years ago.
[color=blue]
> I hypothesize that originally Windows accepted only the backslash, and then
> at some time it changed to accept the forward slash as well.[/color]

Nope. AFAIK, it's always accepted '/'. I did C programming on DOS for
years, and I always used '/' since it was too error working with string
literals in C that contain '\'. Those same programs seemed to run fine
under Windows.
[color=blue]
> Does anyone know when that change occurred? Was it with the introduction of
> support for long filenames in NT and Win95?[/color]

I'm not aware that there has ever been a "change". '/' has been OK since
the early DOS days.

--
Grant Edwards grante Yow! WHOA!! Ken and
at Barbie are having TOO
visi.com MUCH FUN!! It must be the
NEGATIVE IONS!!

**Grant Edwards** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

In article <slrnbn74ch.s2. bignose-hates-spam@rose.local domain.fake>, Ben Finney wrote:
[color=blue][color=green]
>> But now, among a small group of cognoscenti, it is a truism that this is a
>> myth, and that Windows will allow you to use either the forward or the
>> backward slash as a pathname separator.[/color]
>
> I highly doubt it, since the forward slash (or just "slash") is the
> conventional Windows command-line option indicator,[/color]

That was configurable back in the DOS days. There was a "well-known" byte in
system RAM that contained the "switch" character. IIRC, DOS even shipped
with a utility to change that value.
[color=blue]
> analogous to the hyphen on Unix. To accept it as the start of a filename
> would break zillions of existing systems, for no appreciable benefit to
> Microsoft.[/color]

Forward slashes always worked fine for me.
[color=blue]
> Python automagically determines the path component separator, os.sep,
> and uses it for most file path transformations to and from the internal
> language's '/'.
>
> <http://www.python.org/doc/2.3.1/lib/os-path.html#l2h-1552>
>
> Is this perhaps what gives you the impression?[/color]

Forward slashes work in C as well.

--
Grant Edwards grante Yow! Yow! It's some people
at inside the wall! This is
visi.com better than mopping!

**Michael Geary** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Grant Edwards wrote:[color=blue]
> I don't remember if the actual DOS system calls accepted '/' or if
> the C library translated. I do know that DOS C programs could
> use '/' for path separator at least 20 years ago.[/color]

It was the DOS system calls.

-Mike

**Jules Dubois** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

On 25 Sep 2003 16:50:49 -0700, in article
<b16e4ef7.03092 51550.724a57f@p osting.google.c om>, Stephen Ferg wrote:
[color=blue]
> When did Windows start accepting the forward slash as a path separator
> character?[/color]

Even MS-DOS 3.3 would accept '/'; the command-line utilities were
programmed to use only '\' without some start-up parameter (PATHSEP?).
Microsoft removed that feature in v4.0 or 5.0. The "kernel" didn't care.

The Windows kernels are the same. The internals of the operating system
accept either.

**Tim Roberts** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Grant Edwards <grante@visi.co m> wrote:[color=blue]
>
>Ben Finney wrote:
>[color=green][color=darkred]
>>> But now, among a small group of cognoscenti, it is a truism that this is a
>>> myth, and that Windows will allow you to use either the forward or the
>>> backward slash as a pathname separator.[/color]
>>
>> I highly doubt it, since the forward slash (or just "slash") is the
>> conventional Windows command-line option indicator,[/color]
>
>That was configurable back in the DOS days. There was a "well-known" byte in
>system RAM that contained the "switch" character. IIRC, DOS even shipped
>with a utility to change that value.[/color]

Yes, indeed. There was a SWITCHAR option in config.sys, and a
corresponding DOS service, until DOS 3.0, when it was removed because they
couldn't make it work with network software.

So, the situation can be summed up rather simply:

* All DOS services since DOS 2.0 and all Windows APIs accept either
forward slash or backslash. Always have.

* None of the standard command shells (CMD or COMMAND) will accept
forward slashes. Even the "cd ./tmp" example given in a previous post
fails.
--
- Tim Roberts, timr@probo.com
Providenza & Boekelheide, Inc.

**Andrew Dalke** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Tim Roberts:[color=blue]
> * None of the standard command shells (CMD or COMMAND) will accept
> forward slashes. Even the "cd ./tmp" example given in a previous post
> fails.[/color]

Yup. I should have copy&pasted rather than just type it in.
It should have been in quotes. The following does work for me

E:\dalke>cd ..

E:\>cd /dalke
The system cannot find the path specified.

E:\>cd ./dalke

E:\>cd "./dalke"

E:\dalke>ver

Windows NT Version 4.0

E:\dalke>

Andrew
dalke@dalkescie ntific.com

**Alex Martelli** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

Grant Edwards wrote:
...[color=blue]
> Nope. AFAIK, it's always accepted '/'. I did C programming on DOS for
> years, and I always used '/' since it was too error working with string
> literals in C that contain '\'. Those same programs seemed to run fine
> under Windows.
>[color=green]
>> Does anyone know when that change occurred? Was it with the introduction
>> of support for long filenames in NT and Win95?[/color]
>
> I'm not aware that there has ever been a "change". '/' has been OK since
> the early DOS days.[/color]

I _think_ (can't be sure...) that at a C-libraries level the switch
occurred either between DOS 1.0 and 1.1, or at the time of release of
2.0. It's hard to say, because MS didn't release a C compiler as a
product back then; however, it seems that, internally, they used C
compilers running on their Unix machines (presumably their own version
of Unix, named Xenix, which they later sold to SCO) to generate some
parts of the DOS stuff of that age. The original QDOS ("Quick and
Dirty OS") that they bought out and resold as DOS 1.0 surely had no
knowledge of forward slashes -- it was basically CP/M disassembled,
hacked and reassembled (all quite illegally of course). Just as surely,
DOS 2.0 had that knowledge (Allen had also hacked into it some Unix
idioms such as I/O redirection and pipes -- some "pipes", redirecting
to a temporary file and then back out of it!, but syntactically Unixoid --
and more generally made it an uneasy mixmash of some concepts and
practice from the CP/M world plus a little from Unix traditions); and
so did the first C compiler, self-hosted on DOS, that MS later sold to
the public (having bought it, I believe, from Lattice).

Alex

**Grant Edwards** · Jul 18 '05, 02:59 AM

Re: When did Windows start accepting forward slash as a path separator?

In article <GpScb.123559$h E5.4229137@news 1.tin.it>, Alex Martelli wrote:
[color=blue][color=green][color=darkred]
>>> Does anyone know when that change occurred? Was it with the introduction
>>> of support for long filenames in NT and Win95?[/color]
>>
>> I'm not aware that there has ever been a "change". '/' has been OK since
>> the early DOS days.[/color]
>
> I _think_ (can't be sure...) that at a C-libraries level the switch
> occurred either between DOS 1.0 and 1.1, or at the time of release of
> 2.0.[/color]

I don't think 1.0 had a hierarchical filesystem at all did it?

IIRC, it was basically the same as CP/M 2.2 and had nothing other than a
"root" directory on each floppy [IIRC, CP/M 3.x had some concept of multiple
directories on a floppy but it wasn't a tree structured FS with "paths" --
it was more like partitioning a floppy into multiple drive letters.]

By the time I got my hands on IBM machines 2.x was in common use, so I only
had a brief exposure to 1.x.

--
Grant Edwards grante Yow! .. I want to perform
at cranial activities with
visi.com Tuesday Weld!!

When did Windows start accepting forward slash as a path separator?

When did Windows start accepting forward slash as a path separator?

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment