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| <html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>The CYGWIN environment variable</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="using.html" title="Chapter 3. Using Cygwin"><link rel="prev" href="proc.html" title="proc"><link rel="next" href="ntsec.html" title="POSIX accounts, permission, and security"></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">The <code class="envar">CYGWIN</code> environment |
| variable</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="proc.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using Cygwin</th><td width="20%" align="right"> <a accesskey="n" href="ntsec.html">Next</a></td></tr></table><hr></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="using-cygwinenv"></a>The <code class="envar">CYGWIN</code> environment |
| variable</h2></div></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="cygwinenv-implemented-options"></a>Implemented options</h3></div></div></div><p>The <code class="envar">CYGWIN</code> environment variable is used to configure |
| many global settings for the Cygwin runtime system. It contains the options |
| listed below, separated by blank characters. Many options can be turned off |
| by prefixing with <code class="literal">no</code>.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: bullet; "><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)export</code> - If set, the final values of these |
| settings are re-exported to the environment as <code class="envar">CYGWIN</code> again. |
| Defaults to off.</p></li><li class="listitem" style="list-style-type: disc"><p> |
| <code class="envar">error_start:Win32filepath</code> - if set, runs |
| <code class="filename">Win32filepath</code> when cygwin encounters a fatal error, which |
| can be useful for debugging. Defaults to not set. |
| </p><p> |
| <code class="filename">Win32filepath</code> is typically set to <span class="command"><strong>gdb</strong></span> or |
| <span class="command"><strong>dumper</strong></span>. If giving a path in |
| <code class="filename">Win32filepath</code>, note that it is a Windows-style path and not |
| a Cygwin path. |
| </p><p> |
| The filename of the executing program and it's Windows process id are appended |
| to the command as arguments. |
| </p><p> |
| Note: This takes priority over writing core dump or .stackdump files, if |
| enabled by <code class="function">setrlimit(RLIMIT_CORE)</code> (e.g. via |
| <span class="command"><strong>ulimit -c</strong></span>). |
| </p><p> |
| Note: This has no effect if a debugger is already attached when the fatal |
| error occurs. |
| </p><p> |
| Note: The command invoked must either (i) attach to the errored process with |
| <code class="function">DebugActiveProcess()</code>, or (ii) forcibly terminate the |
| errored process (with <code class="function">TerminateProcess()</code> or similar), as |
| otherwise the errored process will wait forever for a debugger to attach. |
| </p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)glob[:ignorecase]</code> - if set, command line arguments |
| containing UNIX-style file wildcard characters (brackets, braces, question mark, |
| asterisk, escaped with \) are expanded into lists of files that match |
| those wildcards. |
| This is applicable only to programs run from non-Cygwin programs such as a CMD prompt. |
| That means that this setting does not affect globbing operations for shells such as |
| bash, sh, tcsh, zsh, etc. |
| Default is set.</p><p>This option also accepts an optional <code class="literal">[no]ignorecase</code> modifer. |
| If supplied, wildcard matching is case insensitive. The default is <code class="literal">noignorecase</code></p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)pipe_byte</code> - if set, Cygwin opens pipes in byte mode rather than |
| message mode. This is the default starting with Cygwin 3.4.0. |
| </p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">proc_retry:n</code> - causes <code class="function">fork()</code> and |
| <code class="function">exec*()</code> to retry n times when a child process fails |
| due to certain windows-specific errors. These errors usually occur when |
| processes are being started while a user is logging off. |
| </p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)reset_com</code> - if set, serial ports are reset |
| to 9600-8-N-1 with no flow control when used. This is done at open |
| time and when handles are inherited. Defaults to set.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)wincmdln</code> - if set, the windows complete command |
| line (truncated to ~32K) will be passed on any processes that it creates |
| in addition to the normal UNIX argv list. Defaults to set.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)winjitdebug</code> - if set, non-Cygwin executables |
| started from a Cygwin process will have their error mode reset to the |
| system default. That means, if they don't call SetErrorMode() |
| explicitly, the OS will display error dialog boxes in the GUI if some |
| fatal error occurs. Defaults to not set, so fatal errors in a |
| non-Cygwin child process will just result in an error code be propagated |
| back to the parent process.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">winsymlinks:{lnk,native,nativestrict,sys}</code></p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: square; "><li class="listitem" style="list-style-type: square"><p>If set to just |
| <code class="literal">winsymlinks</code> or <code class="literal">winsymlinks:lnk</code>, |
| Cygwin creates symlinks as Windows shortcuts with a special header and |
| the R/O attribute set.</p></li><li class="listitem" style="list-style-type: square"><p>If set to <code class="literal">winsymlinks:native</code> or |
| <code class="literal">winsymlinks:nativestrict</code>, Cygwin creates symlinks as |
| native Windows symlinks on filesystems and OS versions supporting them.</p><p>The difference between <code class="literal">winsymlinks:native</code> and |
| <code class="literal">winsymlinks:nativestrict</code> is this: If the filesystem |
| supports native symlinks and Cygwin fails to create a native symlink for |
| some reason, it will fall back to creating Cygwin default symlinks |
| with <code class="literal">winsymlinks:native</code>, while with |
| <code class="literal">winsymlinks:nativestrict</code> the <code class="literal">symlink(2)</code> |
| system call will immediately fail.</p></li><li class="listitem" style="list-style-type: square"><p>If set to <code class="literal">winsymlinks:sys</code>, Cygwin creates symlinks as |
| plain files with the <code class="literal">system</code> attribute, containing a magic |
| cookie followed by the path to which the link points.</p></li></ul></div><p>Note that this setting has no effect where Cygwin knows that the |
| filesystem only supports a creating symlinks in a specific way.</p><p>For more information on symbolic links, see |
| <a class="xref" href="using.html#pathnames-symlinks" title="Symbolic links">the section called “Symbolic links”</a>.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">disable_pcon</code> - if set, pseudo console support in |
| pty will be disabled. This is for programs which do not work properly |
| under pty with pseudo console enabled. Defaults to not set.</p></li></ul></div></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="cygwinenv-removed-options"></a>Obsolete options</h3></div></div></div><p> |
| Certain CYGWIN options available in past releases have been removed over |
| time for one reason or another. These obsolete options are listed |
| below.</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: bullet; "><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)binmode</code> - This option has been removed because |
| all file opens default to binary mode, unless the open mode has been specified |
| explicitly in the open(2) call. |
| </p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)detect_bloda</code> - No case of a BLODA found by this |
| option has been reported in years.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)dosfilewarning</code> - This option had been disabled for |
| quite some time and nobody missed it.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">check_case</code> - This option has been removed in favor of |
| real case sensitivity and the per-mount option "posix=[0|1]". For more |
| information, read the documentation in <a class="xref" href="using.html#mount-table" title="The Cygwin Mount Table">the section called “The Cygwin Mount Table”</a> and |
| <a class="xref" href="using-specialnames.html#pathnames-casesensitive" title="Case sensitive filenames">the section called “Case sensitive filenames”</a>.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">codepage:[ansi|oem]</code> - This option controlled |
| which character set is used for file and console operations. Since Cygwin |
| is now doing all character conversion by itself, depending on the |
| application call to the <code class="function">setlocale()</code> function, and in |
| turn by the setting of the environment variables <code class="envar">$LANG</code>, |
| <code class="envar">$LC_ALL</code>, or <code class="envar">$LC_CTYPE</code>, this setting |
| became superfluous.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)envcache</code> - Originally, <code class="envar">envcache</code> |
| controlled caching of environment variable conversion between Win32 and |
| POSIX. The default setting works fine, the option was just useless.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">forkchunk:[intval]</code> - This option allowed to influence |
| the <code class="function">fork()</code> function in the way the memory of the |
| parent process gets copied to the child process. This functionality was |
| only useful for Windows 95/98/Me. |
| </p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)ntea</code> - This option has been removed since it |
| only fakes security which is considered dangerous and useless. It also |
| created an uncontrollably large file on FAT and was entirely useless |
| on FAT32.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)ntsec</code> - This option has been removed in favor of |
| the per-mount option "acl"/"noacl". For more information, read the |
| documentation in <a class="xref" href="using.html#mount-table" title="The Cygwin Mount Table">the section called “The Cygwin Mount Table”</a>.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)server</code> - Originally this option had to be |
| enabled on the client side to use features only available when running |
| <span class="command"><strong>cygserver</strong></span>. This option has been removed because Cygwin now |
| always tries to contact cygserver if a function is called which requires |
| cygserver being available. For more information, read the documentation |
| in <a class="xref" href="using-cygserver.html" title="Cygserver">the section called “Cygserver”</a>.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)smbntsec</code> - This option has been removed in favor of |
| the per-mount option "acl"/"noacl". For more information, read the |
| documentation in <a class="xref" href="using.html#mount-table" title="The Cygwin Mount Table">the section called “The Cygwin Mount Table”</a>.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)strip_title</code> - Removed because setting the Window title |
| can be controlled by the application via Escape sequences.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)title</code> - Removed because setting the Window title |
| can be controlled by the application via Escape sequences.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)transparent_exe</code> - This option has been removed |
| because the behaviour it switched on is now the standard behaviour in |
| Cygwin.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)traverse</code> - This option has been removed because |
| traverse checking is not quite correctly implemented by Microsoft and |
| it's behaviour has been getting worse with each new OS version. This |
| complicates its usage so the option has been removed for now.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)tty</code> - If set, Cygwin enabled extra support |
| (i.e., termios) for UNIX-like ttys in the Windows console. This option |
| has been removed because it can be easily replaced by using a terminal |
| like <span class="command"><strong>mintty</strong></span>, and it does not work well with some |
| Windows programs.</p></li><li class="listitem" style="list-style-type: disc"><p><code class="envar">(no)upcaseenv</code> - This option could be used to convert |
| all environment variables to uppercase. This was the default behavior in |
| older releases of Cygwin. Since keeping the case of environment variables |
| intact is POSIXly correct, Cygwin now does not change the case |
| of environment variables, except for a restricted set to maintain minimal |
| backward compatibility. The current list of always uppercased variables is: |
| </p><pre class="screen"> |
| COMMONPROGRAMFILES |
| COMSPEC |
| PATH |
| SYSTEMDRIVE |
| SYSTEMROOT |
| TEMP |
| TMP |
| WINDIR |
| </pre></li></ul></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="proc.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ntsec.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">proc </td><td width="20%" align="center"><a accesskey="h" href="cygwin-ug-net.html">Home</a></td><td width="40%" align="right" valign="top"> POSIX accounts, permission, and security</td></tr></table></div></body></html> |
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