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Date: Tue, 01 Dec 2009 11:32:57 -0500
From: Ken Brown <kbrown AT cornell DOT edu>
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To: cygwin AT cygwin DOT com
Subject: Re: Environment variable documentation
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On 12/1/2009 4:45 AM, Corinna Vinschen wrote:
> On Nov 30 17:04, Ken Brown wrote:
>> The discussion currently going on in the thread
>>
>>   http://cygwin.com/ml/cygwin/2009-11/threads.html#00892
>>
>> makes me think that the section on environment variables in the
>> user's guide (http://cygwin.com/1.7/cygwin-ug-net/setup-env.html)
>> could use some expansion.  For example, it's not stated explicitly
>> which Windows environment variables get imported into Cygwin (all of
>> them?), nor is there a complete list of variables containing paths
> 
> Yes, all of them.
> 
>> that get converted to Unix format.  PATH, HOME, and LD_LIBRARY_PATH
>> are mentioned, but TMPDIR, TMP, and TEMP are omitted.  I think the
>> last three should be listed, along with the suggestion that users
>> might want to unset them in the Cygwin environment.
> 
> Yes, TMPDIR, TMP, and TEMP are handled the same way as PATH, HOME, and
> LD_LIBRARY_PATH.  These six variables are the set of environment
> variables which are subject to path conversion from Windows to POSIX and
> vice versa.
> 
>> I would be willing to take a stab at writing a patch if the
>> developers think this would be useful.
> 
> That sounds like a nice idea.

OK, my patch is attached.  It anticipates the change to the default 
.bashrc file that we've been discussing in the thread cited above.

Ken

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--- setup2.sgml.orig	2009-12-01 10:37:00.156250000 -0500
+++ setup2.sgml	2009-12-01 11:29:53.562500000 -0500
@@ -4,7 +4,9 @@
 You may wish to specify settings of several important environment
 variables that affect Cygwin's operation.  Some of these settings need
 to be in effect prior to launching the initial Cygwin session (before
-starting your bash shell, for instance), and are, consequentially, best
+starting your bash shell, for instance).  They should therefore be set
+in the Windows environment; all Windows environment variables are
+imported when Cygwin starts.  Such settings can be
 placed in a .bat file.  An initial file is named Cygwin.bat and is created
 in the Cygwin root directory that you specified during setup.  Note that
 the "Cygwin" option of the Start Menu points to Cygwin.bat.  Edit
@@ -66,6 +68,21 @@
 <function>dlopen ()</function> call and do not need this variable.
 </para>
 
+<para>
+In addition to <envar>PATH</envar>, <envar>HOME</envar>,
+and <envar>LD_LIBRARY_PATH</envar>, there are three other environment
+variables which, if they exist in the Windows environment, are
+converted to UNIX format: <envar>TMPDIR</envar>, <envar>TMP</envar>,
+and <envar>TEMP</envar>.  The first is not set by default in the
+Windows environment but the other two are, and they point to the
+default Windows temporary directory.  If set, these variables will be
+used by some Cygwin applications, possibly with unexpected results.
+They are therefore unset in the default <filename>.bashrc</filename>
+file (<filename>/etc/defaults/etc/skel/.bashrc</filename>).  You may
+prefer to set them to point to <filename>/tmp</filename> or to any
+other temporary directory of your choice.
+</para>
+
 </sect1>
 
 <sect1 id="setup-maxmem"><title>Changing Cygwin's Maximum Memory</title>


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