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| <html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Environment Variables</title><link rel="stylesheet" type="text/css" href="docbook.css"><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="cygwin-ug-net.html" title="Cygwin User's Guide"><link rel="up" href="setup-net.html" title="Chapter 2. Setting Up Cygwin"><link rel="prev" href="setup-net.html" title="Chapter 2. Setting Up Cygwin"><link rel="next" href="setup-maxmem.html" title="Changing Cygwin's Maximum Memory"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Environment Variables</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="setup-net.html">Prev</a> </td><th width="60%" align="center">Chapter 2. Setting Up Cygwin</th><td width="20%" align="right"> <a accesskey="n" href="setup-maxmem.html">Next</a></td></tr></table><hr></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="setup-env"></a>Environment Variables</h2></div></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="setup-env-ov"></a>Overview</h3></div></div></div><p> |
| All Windows environment variables are imported when Cygwin starts. |
| Apart from that, you may wish to specify settings of several important |
| environment variables that affect Cygwin's operation.</p><p> |
| The <code class="envar">CYGWIN</code> variable is used to configure a few global |
| settings for the Cygwin runtime system. Typically you can leave |
| <code class="envar">CYGWIN</code> unset, but if you want to set one ore more |
| options, you can set it using a syntax like this, depending on the shell |
| in which you're setting it. Here is an example in CMD syntax:</p><pre class="screen"> |
| <code class="prompt">C:\></code> <strong class="userinput"><code>set CYGWIN=error_start:C:\cygwin\bin\gdb.exe glob</code></strong> |
| </pre><p> |
| This is, of course, just an example. For the recognized settings of the |
| <code class="envar">CYGWIN</code> environment variable, see |
| <a class="xref" href="using-cygwinenv.html" title="The CYGWIN environment variable">the section called “The <code class="envar">CYGWIN</code> environment |
| variable”</a>. |
| </p><p> |
| Locale support is controlled by the <code class="envar">LANG</code> and |
| <code class="envar">LC_xxx</code> environment variables. For a more detailed description |
| see <a class="xref" href="setup-locale.html" title="Internationalization">the section called “Internationalization”</a>. |
| </p><p> |
| The <code class="envar">PATH</code> environment variable is used by Cygwin |
| applications as a list of directories to search for executable files |
| to run. This environment variable is converted from Windows format |
| (e.g. <code class="filename">C:\Windows\system32;C:\Windows</code>) to UNIX format |
| (e.g., <code class="filename">/cygdrive/c/Windows/system32:/cygdrive/c/Windows</code>) |
| when a Cygwin process first starts. |
| Set it so that it contains at least the <code class="filename">x:\cygwin\bin</code> |
| directory where "<code class="filename">x:\cygwin</code> is the "root" of your |
| cygwin installation if you wish to use cygwin tools outside of bash. |
| This is usually done by the batch file you're starting your shell with. |
| </p><p> |
| The <code class="envar">HOME</code> environment variable is used by many programs to |
| determine the location of your home directory. This environment variable, |
| if it exists, is converted from Windows format when a Cygwin process first |
| starts. However, it's usually set in the shell profile scripts in the /etc |
| directory, and it's <span class="bold"><strong>not</strong></span> recommended to set |
| the variable in your Windows environment. |
| </p><p> |
| The <code class="envar">TERM</code> environment variable specifies your terminal |
| type. It is automatically set to <code class="literal">cygwin</code> if you have |
| not set it to something else. |
| </p><p>The <code class="envar">LD_LIBRARY_PATH</code> environment variable is used by |
| the Cygwin function <code class="function">dlopen ()</code> as a list of |
| directories to search for .dll files to load. This environment variable |
| is converted from Windows format to UNIX format when a Cygwin process |
| first starts. Most Cygwin applications do not make use of the |
| <code class="function">dlopen ()</code> call and do not need this variable. |
| </p><p>The <code class="envar">GMON_OUT_PREFIX</code> environment variable is helpful |
| in some situations when profiling Cygwin programs. For more information, |
| see <a class="xref" href="gprof.html#gprof-fork" title="Profiling programs that fork">the section called “Profiling programs that fork”</a>. Only software developers with a |
| need to profile their programs have a use for this variable. |
| </p><p> |
| In addition to <code class="envar">PATH</code>, <code class="envar">HOME</code>, |
| <code class="envar">LD_LIBRARY_PATH</code>, and <code class="envar">GMON_OUT_PREFIX</code>, |
| there are three other environment |
| variables which, if they exist in the Windows environment, are |
| converted to UNIX format: <code class="envar">TMPDIR</code>, <code class="envar">TMP</code>, |
| and <code class="envar">TEMP</code>. 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. |
| You may therefore want to unset them by adding the following two lines |
| to your <code class="filename">~/.bashrc</code> file: |
|
|
| </p><pre class="screen"> |
| unset TMP |
| unset TEMP |
| </pre><p> |
|
|
| This is done in the default <code class="filename">~/.bashrc</code> file. |
| Alternatively, you could set <code class="envar">TMP</code> |
| and <code class="envar">TEMP</code> to point to <code class="filename">/tmp</code> or to |
| any other temporary directory of your choice. For example: |
|
|
| </p><pre class="screen"> |
| export TMP=/tmp |
| export TEMP=/tmp |
| </pre><p> |
| </p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="setup-env-win32"></a>Restricted Win32 environment</h3></div></div></div><p>There is a restriction when calling Win32 API functions which |
| require a fully set up application environment. Cygwin maintains its own |
| environment in POSIX style. The Win32 environment is usually stripped |
| to a bare minimum and not at all kept in sync with the Cygwin POSIX |
| environment.</p><p>If you need the full Win32 environment set up in a Cygwin process, |
| you have to call</p><pre class="screen"> |
| #include <sys/cygwin.h> |
|
|
| cygwin_internal (CW_SYNC_WINENV); |
| </pre><p>to synchronize the Win32 environment with the Cygwin environment. |
| Note that this only synchronizes the Win32 environment once with the |
| Cygwin environment. Later changes using the <code class="function">setenv</code> |
| or <code class="function">putenv</code> calls are not reflected in the Win32 |
| environment. In these cases, you have to call the aforementioned |
| <code class="function">cygwin_internal</code> call again.</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="setup-net.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="setup-net.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="setup-maxmem.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 2. Setting Up Cygwin </td><td width="20%" align="center"><a accesskey="h" href="cygwin-ug-net.html">Home</a></td><td width="40%" align="right" valign="top"> Changing Cygwin's Maximum Memory</td></tr></table></div></body></html> |
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