echo. with curious output

[mfm4aa]

Hi, I have a curious output with the echo command in XP.
I have the following folders & files:

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C:\TEST
├───folder1
│       file1.iso
│
├───folder10
│       file10.iso
│
├───folder2
│       file2.iso
│
├───folder3
│       file3.iso
│
├───folder4
│       file4.iso
│
├───folder5
│       file5.iso
│
├───folder6
│       file6.iso
│
├───folder7
│       file7.iso
│
├───folder8
│       file8.iso
│
└───folder9
        file9.iso

and this batch code:

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@echo off &setlocal
for /r %%i in (*.iso) do for /f "delims=" %%j in ("%%~dpi.") do echo."%%~dpi%%~nj"
endlocal

and I got this curious output:

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"C:\TEST\folder1\folder1"
"C:\TEST\folder10\folder10"."C:\TEST\folder1\folder1"
"C:\TEST\folder2\folder2"."C:\TEST\folder1\folder1"
"C:\TEST\folder3\folder3"."C:\TEST\folder1\folder1"
"C:\TEST\folder4\folder4"."C:\TEST\folder1\folder1"
"C:\TEST\folder5\folder5"."C:\TEST\folder1\folder1"
"C:\TEST\folder6\folder6"."C:\TEST\folder1\folder1"
"C:\TEST\folder7\folder7"."C:\TEST\folder1\folder1"
"C:\TEST\folder8\folder8"."C:\TEST\folder1\folder1"
"C:\TEST\folder9\folder9"."C:\TEST\folder1\folder1"

and with this code:

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@echo off &setlocal
for /r %%i in (*.iso) do for /f "delims=" %%j in ("%%~dpi.") do echo("%%~dpi%%~nj"
endlocal

that normal output:

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"C:\TEST\folder1\folder1"
"C:\TEST\folder10\folder10"
"C:\TEST\folder2\folder2"
"C:\TEST\folder3\folder3"
"C:\TEST\folder4\folder4"
"C:\TEST\folder5\folder5"
"C:\TEST\folder6\folder6"
"C:\TEST\folder7\folder7"
"C:\TEST\folder8\folder8"
"C:\TEST\folder9\folder9"

Does anybody know the reason for this different behaviour (echo "." vs. "(")?

[foxidrive]

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@echo off
for /f "delims=" %%a in (' dir *.iso /b /s /a-d ') do echo "%%a"

[Aacini]

Your code show us another one of the (multiple) reasons to NOT use "ECHO.". You may review a more detailed explanation of this matter in this thread.

Antonio

[foxidrive]

It looks to be a bug in for /r

This works:

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@echo off &setlocal
for /f "delims=" %%i in (' dir *.iso /b /s ') do for /f "delims=" %%j in ("%%~dpi.") do echo."%%~dpi%%~nj"
endlocal
pause

[jeb]

Interessting effect

Like foxidrive said, it seems to be a bug in FOR /R.
But the bug seems to remove the line ending of the echo command.

This is enough for the bug, you need at least one subdirectory with another subdirectory.

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for /r %%i in ("xyz") do echo.#

#
#.#

But the following echo variants also fail.

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echo:
echo/
echo\
echo[
echo]
echo+

These one works

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echo(
echo=
echo;
echo,

And one appended space supresses the bug.

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for /r %%i in ("xyz") do echo.#<space>

After some experiments I create this one

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@echo OFF
setlocal EnableDelayedExpansion
set n=0
echo ON
for /r %%i in ("xyz") do set /a n+=1& echo%~1#!n!

It's the FOR-Loop expansion, which fails

C:\temp\Sub1>for /R %i in ("xyz") do set /a n+=1 & echo.#!n!
C:\temp\Sub1>set /a n+=1 & echo.#!n!
#1
C:\temp\Sub1>set /a n+=1 & echo.#!n!.#1
#2.#1

The second expansion is very odd, the last output is appended to the new expansion

jeb

[dbenham]

OMG, another batch stunner.

The bug is not XP specific. I also see the bug on Windows 7. (No more Vista for me My hard drive crapped out and I replaced it and upgraded to Win 7/64)

Good sleuthing jeb
For anyone that couldn't figure jeb's code out, simply pass a dot as the lone argument to see the effect. Or pass any other character to test which characters work and which don't, as jeb has already done.

I simplified the code to the following

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@setlocal EnableDelayedExpansion
@for /r %%i in ("xyz") do echo%~1!random!

I agree the bug is with FOR /R. I wish I understood the special parsing rules of FOR better. It seems more of a parsing bug then an expansion bug to me.

The ECHO command is not directly related to the bug, though it is the only command I have found that fully expresses the problem. The VER/? command (with ECHO ON) demonstrates the bug, though it has no impact on the final output. The echoed command still manifests the bug - the /? is doubled. Since the VER output is not changed by the extra /?, I redirected output to NUL.

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@for /r %%i in ("xyz") do >nul ver/?

--OUTPUT--

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C:\test>ver/?1>nul

C:\test>ver/?/? 1>nul

C:\test>ver/?/? 1>nul

Each command within the DO clause can be affected independently. The space after the command token prevents the bug in the middle ECHO command.

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@setlocal EnableDelayedExpansion
@for /r %%i in ("xyz") do echo.!random!&echo.!random! &echo.!random!

--OUTPUT--

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C:\test>echo.!random! & echo.!random!   & echo.!random!
13706
22062
7174

C:\test>echo.!random!.13706  & echo.!random!   & echo.!random!.7174
28067.13706
15
8436.7174

C:\test>echo.!random!.13706  & echo.!random!   & echo.!random!.7174
11260.13706
7978
12414.7174

Adding parentheses and putting each command on a new line still gives the same result. It just makes the echoed command listing uglier.

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@setlocal EnableDelayedExpansion
@for /r %%i in ("xyz") do (
  echo.!random!x
  echo.!random! x
  echo.!random!x
)

--OUTPUT--

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C:\test>(
echo.!random!x
 echo.!random! x
 echo.!random!x
)
27490x
9526 x
23506x

C:\test>(
echo.!random!x.27490x
 echo.!random! x
 echo.!random!x.23506x
)
27616x.27490x
16260 x
6880x.23506x

C:\test>(
echo.!random!x.27490x
 echo.!random! x
 echo.!random!x.23506x
)
8415x.27490x
13789 x
29795x.23506x

Dave Benham

[jeb]

Hi Dave,

It seems more of a parsing bug then an expansion bug to me.

Yes you are right, it seems to be a parsing issue

It seems only be visible when only a command token exists, but no other token in the line.

No bugs here

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for /r %%i in ("xyz") do (
   echo Hello
   set/a.x,b=60
)

But now, both lines have the bug.

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set a.x=2
for /r %%i in ("xyz") do (
   echo^ Hello
   set/a.x^,b^=60
)

The set command can also be affected, but it's tricky to create a working construct

jeb

[jeb]

I'm played a bit with double delayed expansion and I found another curious effect.

The idea behind the double delayed expansion is to get a similiar expression to the CALL percent expansion like

call set var=%%text:~%idx%%%

Now the code for double delayed expansion

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@echo off
SetLocal EnableExtensions EnableDelayedExpansion
cd "Sub1"
set n=2
set y=abcdefg
set var=empty
@echo on
for /r %%i in ("xyz") do (
   echo^ "var=^!y:~!n!^!
   set^ "var=^!y:~!n!^!
)
@echo off
set var

C:\temp\Sub1>for /R %i in ("xyz") do (
echo "var=^!y:~!n!^!
set "var=^!y:~!n!^!
)

C:\temp\Sub1>(
echo "var=^!y:~!n!^!
set "var=^!y:~!n!^!
)
"var=!y:~2!

C:\temp\Sub1>(
echo "var=^!y:~!n!^! "var=!y:~2!
set "var=^!y:~!n!^! "var
)
"var=!y:~2! "var=cdefg
var=!y:~2!

The interessting part is the last expansion

echo "var=^!y:~!n!^! "var=!y:~2!
set "var=^!y:~!n!^! "var

I can't see the reason, why it expands different for echo^ and set^

jeb

[jeb]

I'm not sure what you have in the sub1 folder.

Ok, I forgot to said: In the Sub1 folder is a Sub2 folder, which itself is empty.

That is required to see the FOR/R-bug

jeb

[dbenham]

I can't see the reason, why it expands different for echo^ and set^

That pesky = must have special significance to the FOR parser when dealing with the SET command.

I can manage to get your double delayed expansion to work with the SET command. Interesting, but not very practical.
I also managed to create a more interesting example for SET /A.

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@echo off
SetLocal EnableExtensions EnableDelayedExpansion
cls
set a=2
set y=abcdefg
echo on&for /r %%i in (xyz) do (
  echo^ test_^^!y:~!a!^^!^=
   set^ test_^^!y:~!a!^^!^=
   set/a^ b^=60
)
@echo off
echo -----------------------------------
set test_
echo b=%b%

--OUTPUT--

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C:\test>(
echo test_^!y:~!a!^!=
 set test_^!y:~!a!^!=
 set/a b=60
)
test_!y:~2!=

C:\test>(
echo test_^!y:~!a!^!= test_!y:~2!=
 set test_^!y:~!a!^!= test_!y:~2!
 set/a b=60/a b=60
)
test_!y:~2!= test_cdefg=
Missing operator.
-----------------------------------
test_!y:~2!= test_cdefg
b=30

Dave Benham