[SOLVED] Question about FOR

[Two-eyes]

Man, I've never seen a complicated for command...

See if I understood it correctly, please:

1)

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FOR /F %%A IN (somefile) DO command
Does this:
- take a LINE from somefile and put it in the variable %%A
-perform commands on %%A

2)

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FOR /F %%A IN ("somestring") DO command
Does this:
- take somestring and put it in %%A
-perform commands on %%A

3)

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FOR /F %%A IN(aCommand) DO command
Does this:
- take a line from the output of the command and put it in %%A
-perform commands on %%A

4)

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FOR /F "delims=[char/s]" %%A IN (somestring or somefile or aCommand) DO command
Does this:
-break up somestring or the line from somefile or the output from aCommand according to [char/s]
- take a broken up part and put it in %%A
-perform commands on %%A
QUESTION does a broken up part continue past the end of a line?

I understand eol, skip and usebackq, but
QUESTION What does the tokens option do?

5)

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FOR /L %%A IN (x y z) DO command
Does this:
-assign x to %%A
-do the command
-increment %%A by y
-if %%A equals z stop, else do the command
-in simple works, a loop

6)

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FOR /R [path] %%A IN (set) DO command
Sorry, I don't understand this at all

7)

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FOR /D IN (set) DO command
If I write /? it says: If set contains wildcards, then specifies to match against directory names instead of file names.  So what happens if it doesn't?

//can't write 8 ) cos it is ...so in this forum, lists should be less than 8 or using letters/roman number
9)

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FOR %%A IN (set) DO command
Don't understand it because:
ALSO, I don't understand what could be in 'set' for /R, /D and this last one.

Please correct any mistakes, and answer QUESTIONs, ALSOs and PSs

Thank you very VERY much
Two-Eyes

PS. Can FORs be nested?

[Salmon Trout]

1) Yes, note that the /F switch means "every line" not "a line".
2) Yes
3) Every line of the command output if there are more than one e.g. DIR, TYPE, whatever
4)

treat line as a series of tokens split by delim chars (default are space and TAB)
specify others in delims= (delims block) e.g. "delims=,.:"

tokens=[specify tokens]

The first token (the one specified in the FOR line) is the EXPLICIT token.

There may be up to 25 more IMPLICIT tokens in one FOR structure. (Because there are 26 letters of the alphabet)
These follow in sequence and are specified by the tokens= part.

e.g.

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FOR /F "tokens=1-3* delims=," %%A in ("cat,dog,horse,the whole zoo") do (
    echo  token 1: %%A
    echo  token 2: %%B
    echo  token 3: %%C
    echo the rest: %%D
    )
   

%%A is cat, %%B is dog, %%C is horse, %%D [created because of the asterisk which means "the rest"] is the whole zoo   
   

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token 1: cat
 token 2: dog
 token 3: horse
the rest: the whole zoo

5) Yes

6) Walks the directory tree starting at a top folder, i.e. successively repeats the command for every file specified in (set) in that folder and every sub(and sub-sub, sub-sub-sub, etc) folder in turn

This code echoes the path and filename of every mp3 file in C:\Myfolder and all subdirectories

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FOR /R "C:\MyFolder" %%A in (*.mp3) do (
    echo %%A
    )

7) lists directories.

for /D %%A in (C:\) do echo %%A echoes C:\
for /D %%A in (C:\*) do echo %%A echoes  all next level sub directories
for /D %%A in (C:\B*) do echo %%A echoes  all next level sub directories whose name starts with B

can't write 8 )

use different symbol like 8: or 8] or 8. 

9) set can be a wildcard or a filename

Note quotes; optional if %%A never has spaces, compulsory if there are spaces

Code: [Select]

for %%A in (*.bat) do (
    copy "%%A" D:\NewFolder
    )


PS. Can FORs be nested?

Yes, but you cannot have more than a certain number of variables active. FOR /? help says max is 52 (A-Z, a-z) but in fact you can use 1-9 and a few other characters as well. I think it is 63 or 64 but beyond 52 is undocumented.
   
   

[Two-eyes]

Great, thanks VERY much .

For number 4): [for other people searching]
if I said

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FOR /F "tokens=1,3 delims=," %%A IN ("cat,dog,horse,the rest") DO(
 ECHO %%A
 ECHO %%B

Output is:

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cat
horse

For number 7)
So it does actions on directories instead of files.

Thank you VERY much

Two-eyes

PS:

PS. Can FORs be nested?

Yes, but you cannot have more than a certain number of variables active. FOR /? help says max is 52 (A-Z, a-z) but in fact you can use 1-9 and a few other characters as well. I think it is 63 or 64 but beyond 52 is undocumented.

I wouldnt want to debug that program

can't write 8 )

use different symbol like 8: or 8] or 8. 

Wow, you are so............. thorough
It just shows you care   

Thanks again,

[Salmon Trout]

Can FORs be nested?

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@echo off
for /f "tokens=1-3 delims=:" %%A in ("big:red:wet") do (
for /f "tokens=1-3 delims=," %%D in ("cat,dog,cow") do (
for /f "tokens=1-3 delims=-" %%G in ("hot-hit-hat") do (
    echo %%A %%D %%G
    echo %%A %%E %%G
    echo %%A %%F %%G
    echo %%B %%D %%G
    echo %%B %%E %%G
    echo %%B %%F %%G
    echo %%C %%D %%G
    echo %%C %%E %%G
    echo %%C %%F %%G
        echo %%A %%D %%H
    echo %%A %%E %%H
    echo %%A %%F %%H
    echo %%B %%D %%H
    echo %%B %%E %%H
    echo %%B %%F %%H
    echo %%C %%D %%H
    echo %%C %%E %%H
    echo %%C %%F %%H
    echo %%A %%D %%I
    echo %%A %%E %%I
    echo %%A %%F %%I
    echo %%B %%D %%I
    echo %%B %%E %%I
    echo %%B %%F %%I
    echo %%C %%D %%I
    echo %%C %%E %%I
    echo %%C %%F %%I
    )
    )
    )
   

Code: [Select]

big cat hot
big dog hot
big cow hot
red cat hot
red dog hot
red cow hot
wet cat hot
wet dog hot
wet cow hot
big cat hit
big dog hit
big cow hit
red cat hit
red dog hit
red cow hit
wet cat hit
wet dog hit
wet cow hit
big cat hat
big dog hat
big cow hat
red cat hat
red dog hat
red cow hat
wet cat hat
wet dog hat
wet cow hat

Hours of fun...

[Salmon Trout]

For number 4): [for other people searching]
if I said

FOR /F "tokens=1,3 delims=," %%A IN ("cat,dog,horse,the rest") DO(
 ECHO %%A
 ECHO %%B


Output is:

cat
horse

No, output is

cat
dog

token 1 cat becomes contents of %%A
token 2 dog becomes contents of %%B (the next letter of the alphabet after A)
token 3 horse becomes contents of %%C (the next letter of the alphabet after B)

[Two-eyes]

Weeeell, that loop didn't have a bug .

No, the answer is cat and horse.  Notice that the tokens are 1 AND 3 not 1 TO 3.

T-E

[Salmon Trout]

Weeeell, that loop didn't have a bug .

No, the answer is cat and horse.  Notice that the tokens are 1 AND 3 not 1 TO 3.

T-E

You're right. I should clean my spectacles!

tokens=1,3 means tokens 1 AND 3.
tokens=1,2,3 and tokens 1-3 mean the same thing
tokens=1-3,5 mean tokens 1 to 3 and token 5

[Two-eyes]

I should clean my spectacles!

I am familiar to that problem, bro.

Now, I know this is off-topic but,
[caps on] Why isn't it described that easily in Computer hope's MS-DOS section[/caps on]
I had to experiment and search a lot before I got it.

I'm simply suggesting an improvement.

er...where can I do this, ie is there a forum or e-mail or something like that?

Two-eyes

[Salmon Trout]

Computer Hope is not intended to be the only source of help and information for people. There are many many web sites and forums where this topic is already covered.

Here are a few links

http://technet.microsoft.com/en-us/library/bb490909.aspx

http://www.robvanderwoude.com/variableexpansion.php

http://groups.google.co.uk/group/alt.msdos.batch.nt/browse_frm/thread/c05f88bc3fe14be6/7a467eebaca21f99?hl=en#7a467eebaca21f99

A good place to look is here

http://groups.google.co.uk/group/alt.msdos.batch.nt/topics?hl=en

[Two-eyes]

Of course.  I'm just saying that it is a little complex to understand at first.  Just a side thought.

[Salmon Trout]

Of course.  I'm just saying that it is a little complex to understand at first.  Just a side thought.

I really do agree that since FOR is the engine of so many batch scripts, that a section of Computerhope dealing with its syntax and some of the things that can (and cannot!) be done with it would be a very good idea. In particular,  the topic of delayed variable expansion is one that keeps appearing in the forum. ("Why can't I set variables in a loop?")

[ValerieMay]

There may be up to 25 more IMPLICIT tokens in one FOR structure. (Because there are 26 letters of the alphabet)

Although not documented by MS, 31 tokens can be used and a total in excess of 65 may be open at any time. 

Most of the printable ASCII chars can be used although some must be Escaped (e.g. ^<) when used.  I've not been able to get % or ~ to perform escaped or not.

Short example:

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@echo off
cls
setlocal

set data= Able Baker Charlie

for /f "tokens=1-3" %%: in ("%data%") do (
    echo %%: %%; %%^<
    echo.
    echo %%^< %%; %%:
    echo.
    echo %%: %%^< %%;
)



[Salmon Trout]

Although not documented by MS, 31 tokens can be used and a total in excess of 65 may be open at any time. 

As I noted,

FOR /? help says max is 52 (A-Z, a-z) but in fact you can use 1-9 and a few other characters as well. I think it is 63 or 64 but beyond 52 is undocumented.   

However, (Opinions may differ) I'd be wary of using these "features" in anything approaching production code, partly out of long habit, and partly out of fear that MS might do something to break code that relies on undocumented behaviour of cmd.exe.

[Salmon Trout]

can't write 8 )

When replying,

1. Click "Additional Options..." (blue link, below "Notify me of replies")
2. Check "Don't use smileys"
3. Now you can type 8)

[Two-eyes]

Thanks....you're very efficient ...but also a little of an 

Two-Eyes %