FOR command for doing loops in DOS? | Off Topic

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#301408 - 09/08/2007 19:55 FOR command for doing loops in DOS?
tfabris carpal tunnel Registered: 20/12/1999 Posts: 31600 Loc: Seattle, WA	If I type: Quote: FOR /? at the command prompt, it says (among other things): Quote: FOR /L %variable IN (start,step,end) DO command [command-parameters] The set is a sequence of numbers from start to end, by step amount. So (1,1,5) would generate the sequence 1 2 3 4 5 and (5,-1,1) would generate the sequence (5 4 3 2 1) Which is exactly what I want to do. But if I create a batch file that looks like this: Quote: @echo off FOR /L %variable IN (1,1,5) DO echo hi pause I get "variable was unexpected at this time", instead of printing the word "hi" five times, which is what I expect it to do. I have tried changing the number of percent signs before the word "variable", changing "variable" to "i" or some other value, and a bunch of other tweaks, but I can't figure out why this thing isn't working as the DOS help says it should. What am I doing wrong? Google isn't helping, strangely. PS: Same results on Vista and XP. _________________________ Tony Fabris
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#301409 - 09/08/2007 20:12 Re: FOR command for doing loops in DOS? [Re: tfabris]
AndrewT old hand Registered: 16/02/2002 Posts: 867 Loc: Oxford, UK	Quote: %variable Specifies a single letter replaceable parameter Change %variable to a single character and it'll work.
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#301410 - 09/08/2007 20:16 Re: FOR command for doing loops in DOS? [Re: AndrewT]
tfabris carpal tunnel Registered: 20/12/1999 Posts: 31600 Loc: Seattle, WA	I tried changing it to %i and it did not work. I ended up changing it to %%1 and that worked. I have no idea why. _________________________ Tony Fabris
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#301411 - 09/08/2007 20:20 Re: FOR command for doing loops in DOS? [Re: tfabris]
AndrewT old hand Registered: 16/02/2002 Posts: 867 Loc: Oxford, UK	Ah, good point. I merely tested it immediately at the CMD prompt. It's documented within XP's "HELP for" as: To use the FOR command in a batch program, specify %%variable instead of %variable.
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#301412 - 09/08/2007 20:37 Re: FOR command for doing loops in DOS? [Re: AndrewT]
tman carpal tunnel Registered: 24/12/2001 Posts: 5528	Quote: To use the FOR command in a batch program, specify %%variable instead of %variable. Inside a batch file, %variable gets replaced by the contents of the environment variable "variable". However, %%variable gets replaced by the text "%variable" itself.
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#301413 - 09/08/2007 20:40 Re: FOR command for doing loops in DOS? [Re: tman]
tfabris carpal tunnel Registered: 20/12/1999 Posts: 31600 Loc: Seattle, WA	okay. I still don't understand why it has to be one character. And why %i didn't work when %1 did work. _________________________ Tony Fabris
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#301414 - 09/08/2007 21:01

Re: FOR command for doing loops in DOS? [Re: tfabris]

tman
carpal tunnel

Registered: 24/12/2001
Posts: 5528

Quote:
okay. I still don't understand why it has to be one character. And why %i didn't work when %1 did work.

The %% is important. %%i and %%1 should both work. %i or %1 won't in a batch file.

As for single character variable names:

Code:


C:\>help for
Runs a specified command for each file in a set of files.

FOR %variable IN (set) DO command [command-parameters]

  %variable  Specifies a single letter replaceable parameter.
  (set)      Specifies a set of one or more files.  Wildcards may be used.
  command    Specifies the command to carry out for each file.
  command-parameters
             Specifies parameters or switches for the specified command.

To use the FOR command in a batch program, specify %%variable instead
of %variable.  Variable names are case sensitive, so %i is different
from %I.
<CHOP>

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#301415 - 09/08/2007 21:22 Re: FOR command for doing loops in DOS? [Re: tfabris]
AndrewT old hand Registered: 16/02/2002 Posts: 867 Loc: Oxford, UK	Quote: And why %i didn't work when %1 did work. You probably have command extensions turned off somehow. Try opening a new CMD window using "cmd /e:on" and see if your batch file works with %i. The CMD options are sparsely documented here.
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#301416 - 10/08/2007 15:44 Re: FOR command for doing loops in DOS? [Re: tfabris]
canuckInOR carpal tunnel Registered: 13/02/2002 Posts: 3212 Loc: Portland, OR	Quote: What am I doing wrong? "You still haven't installed cygwin" seems the obvious answer...
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