Multi-line batch script converted to single line command returns different results than the original

Question

I'm trying to transform the multi-line script

@echo off

for /f "eol=: delims=" %%D in ('dir /b /s /ad *^|sort /r') do (
  pushd "%%D"
  for %%F in (*) do move "%%F" "..\%%~nxD - %%F" >nul
  popd
  rd /s /q "%%D"
)
exit

to a single line in order to register it as a context menu entry. To my understanding, the equivalent single line command would be this one:

@echo off && for /f "eol=: delims=" %%D in ('dir /b /s /ad *^|sort /r') do (pushd "%%D" && for %%F in (*) do move "%%F" "..\%%~nxD - %%F" >nul && popd && rd /s /q "%%D") && exit

...but it produces different results than the original script.

Replacing && with & produces a third different result but as far as I know I would still need the && anyway in this case.

What could I be doing wrong?

Answer 1

It turns out that for … do is “greedy”.  (I don’t remember knowing this before, and it doesn’t seem to be prominently documented in for /?.)

Here’s what I mean:

Consider script cow1.bat:

@echo off
for %%a in (how now brown) do echo %%a
echo cow

Pretty trivial.  When run, it outputs

how
now
brown
cow

as we might guess.

Consider script cow2.bat:

@echo off
for %%a in (how now brown) do echo %%a & echo cow

The same, except lines 2 and 3 have been joined, delimited by a &.  Guess what!?  When run, it outputs

how
cow
now
cow
brown
cow

It’s being interpreted as if it were

@echo off
for %%a in (how now brown) do (echo %%a & echo cow)

(Changing & to && didn’t have any effect.)  In a (to me) bigger surprise,

@echo off
for %%a in (how now brown) do (echo %%a) & echo cow

also functioned the same as cow2.  I had to use

@echo off
(for %%a in (how now brown) do echo %%a) & echo cow

to get the original, cow1 behavior.

---

How does this affect the OP?

for %%F in (*) do move "%%F" "..\%%~nxD - %%F" >nul && popd && rd /s /q "%%D"

is analogous to cow2:  If %%D (the directory we just pushd’ed into) is beatles, then the above code segment does this:

move "george" "..\beatles - george" >nul    &&    popd    &&    rd /s /q "beatles"
move "john"   "..\beatles - john"   >nul    &&    popd    &&    rd /s /q "beatles"
move "paul"   "..\beatles - paul"   >nul    &&    popd    &&    rd /s /q "beatles"
move "ringo"  "..\beatles - ringo"  >nul    &&    popd    &&    rd /s /q "beatles"

(whitespace added for clarity).  So it’s moving the first file (george), and then popd’ing out of the beatles directory and deleting it, leaving the other files to be reaped by the roomba.

Recommendation (TL;DR)

Try

for /f "eol=: delims=" %%D in ('dir /b /s /ad *^|sort /r') do (pushd "%%D" && (for %%F in (*) do move "%%F" "..\%%~nxD - %%F" >nul) && popd && rd /s /q "%%D")
                                                                              ↑                                                   ↑

 

Trivial question:

Why do we need the * in the dir /b /s /ad * subcommand?