Re: Persisting env vars in cmd windows

Hi Richard,

It's always a little disappointing when preparing a fine batch file
solution for a poster and when that person takes no further interest
other than using the ready made solution. There is much more fun
in showing a poster what can be done, i.e. responding to a lively
interest from that person.

The help text for the command you question goes like this:
=================
%PATH:~10,5%

would expand the PATH environment variable, and then use only the 5
characters that begin at the 11th (offset 10) character of the expanded
result.
=================
So how does this relate to "%date:~0,3%"? Here we go:
- %date% is an inbuilt variable. You can see its value and
format by typing this: echo %date%
- The first 3 characters of %date% are "Fri".
- The instruction "%date:~0,3%" will take the first 3 characters,
starting at the very beginning (position 0), hence it will write
"Fri" to the screen.

Depending on what programming language you have used, you
might have called this a substring, leftstring or midstring.

I suggest you plug in some other numbers, e.g.
echo "%date:~4,8%" or
echo %date:~4%

Enjoy!

"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx> wrote in message
news:1163127129.738522.168310@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Pegasus,

I don't think that Set /? documents "%date:~0,3%" very well. But no
matter, because executing your examples shows that the expression is
akin to Active Server Pages or Embedded Ruby.

I fear I've taken up too much of your time. Thanks for your responses.
BTW, I'll go back and click stars for some of them.

Best wishes,
Richard

Pegasus (MVP) wrote:
The syntax for the two sample commands is visible when you type

set /?

even though it applies to any command, e.g. echo, copy,
del etc.

Similarly the syntax for the extremely powerful "for" command
is visible when you type

for /?

"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx> wrote in
message
news:1163044747.681567.64680@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Pegasus,

echo Today is %date:~0,3%
echo The time is %time::=.%

Thanks for the additional "toys". I've recorded them in my test
folder
K:\_Projects\CmdScripts\Time&Date and tested them.

I've got perhaps a dozen sites (half from Microsoft) on command
scripts, but I didn't spot any documentation on this specific syntax.
Can you point me to an on-line source?

you must make sure that neither side of the = sign is ever blank.

Duly noted. Thanks.

Regarding starting up several command windows with Start commands,
being able to set the captions in those windows is very helpful. When
I set them up manually before, I only had useful captions on windows
that were active running some command, e.g. the Ruby/Rails logger or
MySQL.

Again, many thanks for your advice.

Best wishes,
Richard


Pegasus (MVP) wrote:
Thanks for the feedback. You'll probably find out a lot
more about batch files as you go on, especially when it
comes to the "set" and "for" commands. Try this from
a Command Prompt just for fun:

echo Today is %date:~0,3%
or
echo The time is %time::=.%

About testing equality without surrounding quotes or brackets

if %result%==OK

you must make sure that neither side of the = sign is ever blank.
If there is the slightest possibility, add some extra characters.
If you don't then the batch file will fail.

"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx> wrote in
message
news:1163009213.990774.115580@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Pegasus,

Great batch template! Thanks.

I tested all the features. I was surprised by a couple of things,
like the "/i" switch and the use of OK without surrounding quotes.

But the piece de resistance was the "start" command, which you
mentioned earlier but I hadn't picked up on right away. Along with
the
other improvements, I got to it now and got exactly what I've got
exactly what I want:

Startup.bat
----------------
START "BAT1 Commands" Bat1.bat
START "BAT2 Commands" Bat2.bat
: etc

let's me double-click its name and get precisely the command
windows I
want to support my Ruby/Rails application development efforts.

It's embarrassing to admit that I've used Windows' bat files for
decades but never noticed some of the features you've mentioned.
Again, thanks for your expert help.

Best wishes,
Richard

Pegasus (MVP) wrote:
When you ask about combining your various batch files
into the one file then you're spot on. The general idea is:
- Have all code for the one project in one single batch file.
- Make it highly structured.
- Avoid spaghetti code.
- Set global variables.
- Add lots of comments.

If you adhere to these rules then you will find that your
batch files become much more robust and are very easy
to maintain. You also skirt around the environmental variable
issue that triggered this thread.

I have seen contiguous (rather than modular) batch files that
extend over 300 lines, with numerous goto statements that
resemble the path taken by a hare in full flight. They are
almost
impossible to maintain. In a structured form even a beginner
could debug and modify them.

Here is how I structure all my batch files:
=============================
@echo off
goto Start
--------------------------------------------
Program description:
Parameters:
Prerequisites:
Version:
Author:
Date:
--------------------------------------------
:Start
set SourceDir=D:\Some Folder
set TargetDir=E:\Other folder
call :Sub1
call :Sub2 %name%
if /i "%result%"==OK call :Sub3
goto :eof

--------------------------------------------
Some comments about Sub1
--------------------------------------------
:Sub1
Code for Sub1
goto :eof

--------------------------------------------
Some comments about Sub2
--------------------------------------------
:Sub2
Code for Sub2
goto :eof


"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx> wrote
in
message
news:1162878332.440957.299980@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Pegasus,

OK, I've simplified these scripts substantially, e.g.

C130_StartLocalWebServer.bat
(down to 8 lines instead of 20 because the error checking no
longer
needed)
---------------------------------------------
@echo off
call CreatePathAndSymbols.bat _Pf Prmp
echo ::
echo :: Starting WebBrickServer
echo :: in %AppDir%
echo ::
@echo on
ruby script/server

That's just what I wanted.

I appreciate the observations you made, i.e.:
1. Checking for existence of %2 obviates the need to check
for %1
2. :EOF is built-in, obviating the need to define a symbol
at
the
end
of the script

Mainly, I rely on 3 of my ~20 batch commands to start-up
testing a
Ruby/Rails app. I keep those command windows open for the
duration of
a testing/developing session.

Heretofore, I opened three command windows and exectuted two
bath
commands in each.
With your help, I've cut that down to one command in each.

Is there a way to combine that into a single batch command,
e.g.

CombineCommand.bat (pseudocode)
---------------------------------
run cmd.exe; execute batch1.bat
run cmd.exe; execute batch2.bat
run cmd.exe; execute batch3.bat

and achieve the same result I'm getting now?

Again, thanks for your help.

Regards,
Richard


Pegasus (MVP) wrote:
Wow! This is one complex script!

Unfortunately it would take me far too long to analyse and
reverse-engineer it. There is certainly scopy for
simplification.
Here are a few minor ones:

Of the two successive statements
if (%1) == () goto PARM_MISSING
if (%2) == () goto PARM_MISSING
the first one is superfluous. If %2 is blank then %1
must be blank too!

You have lots of "goto EOJ" statements. Replace them
with "goto EOF". This is an inbuilt label that does not
need to be defined.

You write
%RubyDisk%
cd %AppDir%
This should be simplyfied to
cd /d %AppDir%
(where %AppDir% now includes the drive letter).

However, this is just cosmetic stuff. I suspect that the
whole
set of batch files can be condensed to perhaps twenty lines
in a single batch file, which will solve your variable
problems
and will make debugging and further development much, much
easier. You would get a short, sharp and robust batch file.
To suggest how it could be done requires your functional
description of what you're attempting to do. But then you
may
decide that "GO"s suggestion solves your problem, in which
case I will leave you to it.


"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx>
wrote
in
message

news:1162789861.293438.209190@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi Pegasus,

Thanks for responding.

I've got PATH= ... ; K:\_Projects\Ruby\__Links; ...

Below are four batch files. Typically, when I boot up and
want to
work
on the Prmp project, I open several Command windows in
succession.
The first thing I do with each of them is drag in the name
of
and
execute a couple of batch commands, e.g.

1a. Drag the name of C000_CreateSymbols.bat into a new
command
window
1b. Click the command window to give it focus
1c. Press Enter to execute the command, where upon
cwd=K:\_Projects\Ruby\_Pf\Prmp
(and symbols RubyDisk, RubyProj, CliName and AppName
are
defined)
2a. Drag the name of C130_StartLocalWebServer.bat into the
command
window
2b. Click the command window to give it focus
2c. Press Enter to execute the command,
whereupon the ruby starts up the WEBrick web server.

Then I open a second command window, repeat the compound
step
1
and
follow that with a command step 2 with a different batch
command,
e.g.
C160_StartBreakpointer.bat, which starts a listener for
any
breakpoint
command executed in my Ruby/Rails application and starts
an
interactive
ruby session initialized with the application's state.

BTW, as I was documenting my environment for you, it
occurs
to me

that
I can install an invocation of the followin line at the
start
of
all
my
commands (other than C000_...) and ignore C000_...
completely
(and
eliminate all the error traps):

CreatePathAndSymbols.bat _Pf Prmp

I think that'll work. But you can probably show a less
kludgy
way
to
do the whole thing.

Best wishes,
Richard

K:\_Projects\Ruby\__Links\CreatePathAndSymbols.bat




--------------------------------------------------------------------------
------
@echo off
::: Call with arguments ClientName and ApplicationName
:: Note: Names may not include spaces nor most special
characters
::
if (%1) == () goto PARM_MISSING
if (%2) == () goto PARM_MISSING
::
set RubyDisk=K:
set RubyProj=%RubyDisk%\_Projects\Ruby
::
set CliName=%1
set AppName=%2
::
set CliDir=%RubyProj%\%CliName%
set AppDir=%CliDir%\%AppName%
::
%RubyDisk%
cd %AppDir%\
::
path=%CliDir%\Cmds\;%path%
goto EOJ
::
:PARM_MISSING
echo ::
echo :: ERROR ERROR ERROR ERROR
echo :: Usage: %0 ClientName ApplicationName
echo :: ERROR ERROR ERROR ERROR
echo ::
:EOJ

K:\_Projects\Ruby\_Pf\Cmds\C000_CreateSymbols.bat




--------------------------------------------------------------------------
------
@echo off
CreatePathAndSymbols.bat _Pf Prmp
pause

C130_StartLocalWebServer.bat
---------------------------------------------
@echo off
if [%CliDir%] == [] goto ERROR
if [%AppDir%] == [] goto ERROR
if [%RubyDisk%] == [] goto ERROR
%RubyDisk%
cd %AppDir%
echo ::
echo :: Starting WebBrickServer
echo :: in %AppDir%
echo ::
@echo on
ruby script/server
@echo off
goto EXIT
:ERROR
@echo ERROR ERROR ERROR ERROR
@echo Symbol "AppDir", etc., not defined!
@echo ... run CreatePathAndSymbols.bat in your Command
Window
@echo ERROR ERROR ERROR ERROR
:EXIT

C160_StartBreakpointer.bat
----------------------------------------
@echo off
if [%CliDir%] == [] goto ERROR
if [%AppDir%] == [] goto ERROR
if [%RubyDisk%] == [] goto ERROR
%RubyDisk%
cd %AppDir%
echo ::
echo :: Starting a Breakpointer
echo ::
@echo on
ruby script/breakpointer
@echo off
goto EXIT
:ERROR
@echo ERROR ERROR ERROR ERROR
@echo Symbol "AppDir", etc., not defined!
@echo ... run CreatePathAndSymbols.bat in your Command
Window
@echo ERROR ERROR ERROR ERROR
:EXIT


Pegasus (MVP) wrote:
"Richard" <RichardDummyMailbox58407@xxxxxxxxxxxxxxxxxxx>
wrote
in
message

news:1162763712.640301.320540@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I've got a .bat file that sets a number of symbols
(environment
vars)
that are useful in a number of other command windows
associated
with
one of several projects. Right now, I operate by
1 opening a command window
2 draging the name of the symbol-setting bat file into
the
new
cmd
window and pressing Enter
3 draging the name of one of my utility bat files in
the
cmd
window
and
pressing Enter
4 proceeding manually entering other commands as
needed.

I'd like to eliminate step 2 by invoking the
symbol-setter
at
the
beginning of every other utility file. I tried this
by
using
"cmd
/c
symbol-setter.bat" to no avail. I believe that fails
because
the
"cmd
/c" command starts a new session in which to set local
env.
vars
and
then ends, never communicating with the invoking
session.

The best solution I can conceive of is to manually
write a
.reg
file
appropriate to each project in which I want persistant
env.
vars,
thus
only needing to invoke that once at the inception of a
project,
maybe
with another one to delete all such entries should the
project
ultimately be destroyed.

Any comments?

Regards,
Richard


It seems you're trying to combine two different
techniques
with each other: Running batch files (which is
fundamentally
a Command Prompt activity) and dragging files (which is
a GUI activity). A better way would be to run a single
batch
file and perhaps specify some parameters for it.

To obtain correct advice about your environmental
variables
you should post the contents of your batch file. You
should
also state if the variables are supposed to be valid
within
the context of this batch file only, within the context
of
the
Command Prompt session it runs or within the context of
all programs, regardless of when they are launched.







.

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