Variable beginning with a numeral doesn't work as expected in batch file

Frank B Denman · Oct 3, 2008

Hi Folks,

I'm getting into trouble in a batch file when I set a variable name that begins with a number. I'm
hoping somebody can help me understand why.

This batch file works just fine:
-------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET _4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%_4C_FOLDER%">>"%DIR_OUTPUT%"
--------------------------------------------
However, if I lose the leading underscore on the fourth variable, so that the batch file looks like
this:
--------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET 4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%4C_FOLDER%">>"%DIR_OUTPUT%"
--------------------------------------------
The last line now fails. Here's the output at the command prompt:
---------------------------------------------
D:\Temp\test>dirlist

D:\Temp\test>SET A_FOLDER=D:\Temp\test\Able

D:\Temp\test>SET B_FOLDER=D:\Temp\test\Baker

D:\Temp\test>SET C_FOLDER=D:\Temp\test\Charley

D:\Temp\test>SET 4C_FOLDER=D:\Temp\test\4_Charley

D:\Temp\test>SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt

D:\Temp\test>dir "D:\Temp\test\Able" 1>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Baker" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Charley" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "C_FOLDERDIR_OUTPUT"
Volume in drive D is Data
Volume Serial Number is 94B6-1DC6

Directory of D:\Temp\test

File Not Found
D:\Temp\test>
---------------------------------------------
The final dir command seems to have concatenated elements of the line immediately above it. I would
really like to understand why.

Thanks for your help!

Frank

Frank Denman
Denman Systems
(e-mail address removed)
[Please delete the "x" from my email address]

foxidrive · Oct 3, 2008

SET 4C_FOLDER=D:\Temp\test\4_Charley

dir "%4C_FOLDER%">>"%DIR_OUTPUT%"

The final dir command seems to have concatenated elements of the line immediately above it. I would
really like to understand why.

%0 to %9 has a special significance to batch files and the command
interpreter is seeing %4 followed by C_FOLDER etc and a mismatched set of %
signs.

Timo Salmi · Oct 3, 2008

Frank B Denman said:
I'm getting into trouble in a batch file when I set a variable name that begins with a number. I'm
hoping somebody can help me understand why.

Probably similar to
82} Why does echo 9>temp.txt fail while echo 10>temp.txt works?
http://www.netikka.net/tsneti/info/tscmd082.htm
and
http://www.netikka.net/tsneti/info/tscmd086.htm#handle

All the best, Timo

Esra Sdrawkcab · Oct 3, 2008

Frank said:
Hi Folks,

I'm getting into trouble in a batch file when I set a variable name that begins with a number. I'm
hoping somebody can help me understand why.

This batch file works just fine:
-------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET _4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%_4C_FOLDER%">>"%DIR_OUTPUT%"
--------------------------------------------
However, if I lose the leading underscore on the fourth variable, so that the batch file looks like
this:
--------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET 4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%4C_FOLDER%">>"%DIR_OUTPUT%"

the '%4' above is first parsed to substitute the fourth parameter passed
into the batch file, as this is probably blank, you get the other set
string, C_FOLDER instead.

if you called your set 4_C_FOLDER I suggest that the dir command would
fail in a less puzzling manner!

You have already hit upon a good workaround; prepend the numeric
variable names with an underscore (i.e. don't have a variable starting
with a number)

D:\Temp\test>dirlist

D:\Temp\test>SET A_FOLDER=D:\Temp\test\Able

D:\Temp\test>SET B_FOLDER=D:\Temp\test\Baker

D:\Temp\test>SET C_FOLDER=D:\Temp\test\Charley

D:\Temp\test>SET 4C_FOLDER=D:\Temp\test\4_Charley

D:\Temp\test>SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt

D:\Temp\test>dir "D:\Temp\test\Able" 1>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Baker" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Charley" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "C_FOLDERDIR_OUTPUT"
Volume in drive D is Data
Volume Serial Number is 94B6-1DC6

Directory of D:\Temp\test

File Not Found
D:\Temp\test>
---------------------------------------------
The final dir command seems to have concatenated elements of the line immediately above it. I would
really like to understand why.

Thanks for your help!

Frank

Frank Denman
Denman Systems
(e-mail address removed)
[Please delete the "x" from my email address]

Esra Sdrawkcab · Oct 3, 2008

Timo said:
Probably similar to
82} Why does echo 9>temp.txt fail while echo 10>temp.txt works?
http://www.netikka.net/tsneti/info/tscmd082.htm
and
http://www.netikka.net/tsneti/info/tscmd086.htm#handle

All the best, Timo

No, the above is to do with reserved pipe names. But it is best to avoid
numeric names!

Frank B Denman · Oct 3, 2008

Thanks, guys, for all the good advice!

Frank

Frank said:
Frank said:

Hi Folks,

I'm getting into trouble in a batch file when I set a variable name that begins with a number. I'm
hoping somebody can help me understand why.

This batch file works just fine:
-------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET _4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%_4C_FOLDER%">>"%DIR_OUTPUT%"
--------------------------------------------
However, if I lose the leading underscore on the fourth variable, so that the batch file looks like
this:
--------------------------------------------
SET A_FOLDER=D:\Temp\test\Able
SET B_FOLDER=D:\Temp\test\Baker
SET C_FOLDER=D:\Temp\test\Charley
SET 4C_FOLDER=D:\Temp\test\4_Charley
SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt
::
dir "%A_FOLDER%">"%DIR_OUTPUT%"
dir "%B_FOLDER%">>"%DIR_OUTPUT%"
dir "%C_FOLDER%">>"%DIR_OUTPUT%"
dir "%4C_FOLDER%">>"%DIR_OUTPUT%"

Click to expand...

the '%4' above is first parsed to substitute the fourth parameter passed
into the batch file, as this is probably blank, you get the other set
string, C_FOLDER instead.

if you called your set 4_C_FOLDER I suggest that the dir command would
fail in a less puzzling manner!

You have already hit upon a good workaround; prepend the numeric
variable names with an underscore (i.e. don't have a variable starting
with a number)

D:\Temp\test>dirlist

D:\Temp\test>SET A_FOLDER=D:\Temp\test\Able

D:\Temp\test>SET B_FOLDER=D:\Temp\test\Baker

D:\Temp\test>SET C_FOLDER=D:\Temp\test\Charley

D:\Temp\test>SET 4C_FOLDER=D:\Temp\test\4_Charley

D:\Temp\test>SET DIR_OUTPUT=D:\Temp\test\Delta\Appended_Dir_List.txt

D:\Temp\test>dir "D:\Temp\test\Able" 1>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Baker" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "D:\Temp\test\Charley" 1>>"D:\Temp\test\Delta\Appended_Dir_List.txt"

D:\Temp\test>dir "C_FOLDERDIR_OUTPUT"
Volume in drive D is Data
Volume Serial Number is 94B6-1DC6

Directory of D:\Temp\test

File Not Found
D:\Temp\test>
---------------------------------------------
The final dir command seems to have concatenated elements of the line immediately above it. I would
really like to understand why.

Thanks for your help!

Frank

Frank Denman
Denman Systems
(e-mail address removed)
[Please delete the "x" from my email address]

Click to expand...

Frank Denman
Denman Systems
(e-mail address removed)
[Please delete the "x" from my email address]

Variable beginning with a numeral doesn't work as expected in batch file

Frank B Denman

foxidrive

Timo Salmi

Esra Sdrawkcab

Esra Sdrawkcab

Frank B Denman