594 lines
27 KiB
XML
594 lines
27 KiB
XML
<?xml version="1.0" encoding='UTF-8'?>
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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<sect1 id="using-pathnames"><title>Mapping path names</title>
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<sect2 id="pathnames-intro"><title>Introduction</title>
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<para>The Cygwin DLL supports both POSIX- and Win32-style paths. Directory
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delimiters may be either forward slashes or backslashes. Paths using
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backslashes or starting with a drive letter are always handled as
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Win32 paths. POSIX paths must only use forward slashes as delimiter,
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otherwise they are treated as Win32 paths and file access might fail
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in surprising ways.</para>
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<note><para>Although the Cygwin DLL supports Win32 paths, not all
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Cygwin applications support them. Moreover, the usage of Win32 paths
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circumvents important internal path handling mechanisms. This usage
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is therefore strongly deprecated and may be removed in a future
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release of Cygwin.
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See <xref linkend="pathnames-win32"></xref> and
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<xref linkend="pathnames-win32-api"></xref> for more information.
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</para></note>
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<para>POSIX operating systems (such as Linux) do not have the concept
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of drive letters. Instead, all absolute paths begin with a
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slash (instead of a drive letter such as "c:") and all file systems
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appear as subdirectories (for example, you might buy a new disk and
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make it be the <filename>/disk2</filename> directory).</para>
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<para>Because many programs written to run on UNIX systems assume
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the existence of a single unified POSIX file system structure, Cygwin
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maintains a special internal POSIX view of the Win32 file system
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that allows these programs to successfully run under Windows. Cygwin
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uses this mapping to translate from POSIX to Win32 paths as
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necessary.</para>
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</sect2>
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<sect2 id="mount-table"><title>The Cygwin Mount Table</title>
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<para>The <filename>/etc/fstab</filename> file is used to map Win32
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drives and network shares into Cygwin's internal POSIX directory tree.
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This is a similar concept to the typical UNIX fstab file. The mount
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points stored in <filename>/etc/fstab</filename> are globally set for
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all users. Sometimes there's a requirement to have user specific
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mount points. The Cygwin DLL supports user specific fstab files.
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These are stored in the directory <filename>/etc/fstab.d</filename>
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and the name of the file is the Cygwin username of the user, as it's
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created from the Windows account database or stored in the
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<filename>/etc/passwd</filename> file (see
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<xref linkend="ntsec-mapping"></xref>). The structure of the
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user specific file is identical to the system-wide
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<filename>fstab</filename> file.</para>
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<para>The file fstab contains descriptive information about the various file
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systems. fstab is only read by programs, and not written; it is the
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duty of the system administrator to properly create and maintain this
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file. Each filesystem is described on a separate line; fields on each
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line are separated by tabs or spaces. Lines starting with '#' are
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comments.</para>
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<para>The first field describes the block special device or
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remote filesystem to be mounted. On Cygwin, this is the native Windows
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path which the mount point links in. As path separator you MUST use a
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slash. Usage of a backslash might lead to unexpected results. UNC
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paths (using slashes, not backslashes) are allowed. If the path
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contains spaces these can be escaped as <literal>'\040'</literal>.</para>
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<para>The second field describes the mount point for the filesystem.
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If the name of the mount point contains spaces these can be
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escaped as '\040'.</para>
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<para>The third field describes the type of the filesystem. Cygwin supports
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any string here, since the file system type is usually not evaluated. So it
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doesn't matter if you write <literal>FAT</literal> into this field even if
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the filesystem is NTFS. Cygwin figures out the filesystem type and its
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capabilities by itself.</para>
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<para>The only two exceptions are the file system types cygdrive and usertemp.
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The cygdrive type is used to set the cygdrive prefix. For a description of
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the cygdrive prefix see <xref linkend="cygdrive"></xref>, for a description of
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the usertemp file system type see <xref linkend="usertemp"></xref></para>
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<para>The fourth field describes the mount options associated
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with the filesystem. It is formatted as a comma separated list of
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options. It contains at least the type of mount (binary or text) plus
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any additional options appropriate to the filesystem type. The list of
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the options, including their meaning, follows.</para>
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<screen>
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acl - Cygwin uses the filesystem's access control lists (ACLs) to
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implement real POSIX permissions (default). This flag only
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affects filesystems supporting ACLs (NTFS, for instance) and
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is ignored otherwise.
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auto - Ignored.
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binary - Files default to binary mode (default).
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bind - Allows to remount part of the file hierarchy somewhere else.
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In contrast to other entries, the first field in the fstab
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line specifies an absolute POSIX path. This path is remounted
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to the POSIX path specified as the second path. The conversion
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to a Win32 path is done on the fly. Only the root path and
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paths preceding the bind entry in the fstab file are used to
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convert the POSIX path in the first field to an absolute Win32
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path. Note that symlinks are ignored while performing this path
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conversion.
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cygexec - Treat all files below mount point as cygwin executables.
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dos - Always convert leading spaces and trailing dots and spaces to
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characters in the UNICODE private use area. This allows to use
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broken filesystems which only allow DOS filenames, even if they
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are not recognized as such by Cygwin.
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exec - Treat all files below mount point as executable.
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ihash - Always fake inode numbers rather than using the ones returned
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by the filesystem. This allows to use broken filesystems which
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don't return unambiguous inode numbers, even if they are not
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recognized as such by Cygwin.
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noacl - Cygwin ignores filesystem ACLs and only fakes a subset of
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permission bits based on the DOS readonly attribute. This
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behaviour is the default on FAT and FAT32. The flag is
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ignored on NFS filesystems.
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nosuid - No suid files are allowed (currently unimplemented).
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notexec - Treat all files below mount point as not executable.
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nouser - Mount is a system-wide mount.
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override - Force the override of an immutable mount point (currently "/").
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posix=0 - Switch off case sensitivity for paths under this mount point
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(default for the cygdrive prefix).
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posix=1 - Switch on case sensitivity for paths under this mount point
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(default for all other mount points).
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sparse - Switch on support for sparse files. This option only makes
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sense on NTFS and then only if you really need sparse files.
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Cygwin does not try to create sparse files by default for
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performance reasons.
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text - Files default to CRLF text mode line endings.
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user - Mount is a user mount.
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</screen>
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<para>While normally the execute permission bits are used to evaluate
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executability, this is not possible on filesystems which don't support
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permissions at all (like FAT/FAT32), or if ACLs are ignored on filesystems
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supporting them (see the aforementioned <literal>acl</literal> mount option).
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In these cases, the following heuristic is used to evaluate if a file is
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executable: Files ending in certain extensions (.exe, .com, .lnk) are
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assumed to be executable. Files whose first two characters are "#!", "MZ",
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or ":\n" are also considered to be executable.
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The <literal>exec</literal> option is used to instruct Cygwin that the
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mounted file is "executable". If the <literal>exec</literal> option is used
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with a directory then all files in the directory are executable.
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This option allows other files to be marked as executable and avoids the
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overhead of opening each file to check for "magic" bytes. The
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<literal>cygexec</literal> option is very similar to <literal>exec</literal>,
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but also prevents Cygwin from setting up commands and environment variables
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for a normal Windows program, adding another small performance gain. The
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opposite of these options is the <literal>notexec</literal> option, which
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means that no files should be marked as executable under that mount point.</para>
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<para>A correct root directory is quite essential to the operation of
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Cygwin. A default root directory is evaluated at startup so a
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<filename>fstab</filename> entry for the root directory is not necessary.
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If it's wrong, nothing will work as expected. Therefore, the root directory
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evaluated by Cygwin itself is treated as an immutable mount point and can't
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be overridden in /etc/fstab... unless you think you really know what you're
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doing. In this case, use the <literal>override</literal> flag in the options
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field in the <filename>/etc/fstab</filename> file. Since this is a dangerous
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thing to do, do so at your own risk.</para>
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<para><filename>/usr/bin</filename> and <filename>/usr/lib</filename> are
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by default also automatic mount points generated by the Cygwin DLL similar
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to the way the root directory is evaluated. <filename>/usr/bin</filename>
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points to the directory the Cygwin DLL is installed in,
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<filename>/usr/lib</filename> is supposed to point to the
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<filename>/lib</filename> directory. This choice is safe and usually
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shouldn't be changed. An fstab entry for them is not required.</para>
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<para><literal>nouser</literal> mount points are not overridable by a later
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call to <command>mount</command>.
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Mount points given in <filename>/etc/fstab</filename> are by default
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<literal>nouser</literal> mount points, unless you specify the option
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<literal>user</literal>. This allows the administrator to set certain
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paths so that they are not overridable by users. In contrast, all mount
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points in the user specific fstab file are <literal>user</literal> mount
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points.</para>
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<para>The fifth and sixth field are ignored. They are
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so far only specified to keep a Linux-like fstab file layout.</para>
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<para>Note that you don't have to specify an fstab entry for the root dir,
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unless you want to have the root dir pointing to somewhere entirely
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different (hopefully you know what you're doing), or if you want to
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mount the root dir with special options (for instance, as text mount).</para>
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<para>Example entries:</para>
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<itemizedlist spacing="compact">
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<listitem>
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<para>Just a normal mount point:</para>
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<screen> c:/foo /bar fat32 binary 0 0</screen>
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</listitem>
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<listitem>
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<para>A mount point for a textmode mount with case sensitivity switched off:</para>
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<screen> C:/foo /bar/baz ntfs text,posix=0 0 0</screen>
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</listitem>
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<listitem>
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<para>A mount point for a Windows directory with spaces in it:</para>
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<screen> C:/Documents\040and\040Settings /docs ext3 binary 0 0</screen>
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</listitem>
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<listitem>
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<para>A mount point for a remote directory, don't store POSIX permissions in ACLs:</para>
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<screen> //server/share/subdir /srv/subdir smbfs binary,noacl 0 0</screen>
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</listitem>
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<listitem>
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<para>This is just a comment:</para>
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<screen> # This is just a comment</screen>
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</listitem>
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<listitem>
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<para>Set the cygdrive prefix to /mnt:</para>
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<screen> none /mnt cygdrive binary 0 0</screen>
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</listitem>
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<listitem>
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<para>Remount /var to /usr/var:</para>
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<screen> /var /usr/var none bind</screen>
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<para>Assuming <filename>/var</filename> points to
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<filename>C:/cygwin/var</filename>, <filename>/usr/var</filename> now
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also points to <filename>C:/cygwin/var</filename>. This is equivalent
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to the Linux <literal>bind</literal> option available since
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Linux 2.4.0.</para>
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</listitem>
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</itemizedlist>
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<para>Whenever Cygwin generates a Win32 path from a POSIX one, it uses
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the longest matching prefix in the mount table. Thus, if
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<filename>C:</filename> is mounted as <filename>/c</filename> and also
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as <filename>/</filename>, then Cygwin would translate
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<filename>C:/foo/bar</filename> to <filename>/c/foo/bar</filename>.
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This translation is normally only used when trying to derive the
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POSIX equivalent current directory. Otherwise, the handling of MS-DOS
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filenames bypasses the mount table.
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</para>
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<para>If you want to see the current set of mount points valid in your
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session, you can invoke the Cygwin tool <command>mount</command> without
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arguments:</para>
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<example id="pathnames-mount-ex">
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<title>Displaying the current set of mount points</title>
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<screen>
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<prompt>bash$</prompt> <userinput>mount</userinput>
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f:/cygwin/bin on /usr/bin type ntfs (binary,auto)
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f:/cygwin/lib on /usr/lib type ntfs (binary,auto)
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f:/cygwin on / type ntfs (binary,auto)
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e:/src on /usr/src type vfat (binary)
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c: on /cygdrive/c type ntfs (binary,posix=0,user,noumount,auto)
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e: on /cygdrive/e type vfat (binary,posix=0,user,noumount,auto)
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</screen>
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</example>
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<para>You can also use the <command>mount</command> command to add
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new mount points, and the <command>umount</command> to delete
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them. However, since they are only stored in memory, these mount
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points will disappear as soon as your last Cygwin process ends.
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See <xref linkend="mount"></xref> and <xref linkend="umount"></xref> for more
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information.</para>
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</sect2>
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<sect2 id="unc-paths"><title>UNC paths</title>
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<para>Apart from the unified POSIX tree starting at the <filename>/</filename>
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directory, UNC pathnames starting with two slashes and a server name
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(<filename>//machine/share/...</filename>) are supported as well.
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They are handled as POSIX paths if only containing forward slashes. There's
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also a virtual directory <filename>//</filename> which allows to enumerate
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the fileservers known to the local machine with <command>ls</command>.
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Same goes for the UNC paths of the type <filename>//machine</filename>,
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which allow to enumerate the shares provided by the server
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<literal>machine</literal>. For often used UNC paths it makes sense to
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add them to the mount table (see <xref linkend="mount-table"></xref> so
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they are included in the unified POSIX path tree.</para>
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</sect2>
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<sect2 id="cygdrive"><title>The cygdrive path prefix</title>
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<para>As already outlined in <xref linkend="ov-hi-files"></xref>, you can
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access arbitary drives on your system by using the cygdrive path prefix.
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The default value for this prefix is <filename>/cygdrive</filename>, and
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a path to any drive can be constructed by using the cygdrive prefix and
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appending the drive letter as subdirectory, like this:</para>
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<screen>
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bash$ ls -l /cygdrive/f/somedir
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</screen>
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<para>This lists the content of the directory F:\somedir.</para>
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<para>The cygdrive prefix is a virtual directory under which all drives
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on a system are subsumed. The mount options of the cygdrive prefix is
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used for all file access through the cygdrive prefixed drives. For instance,
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assuming the cygdrive mount options are <literal>binary,posix=0</literal>,
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then any file <filename>/cygdrive/x/file</filename> will be opened in
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binary mode by default (mount option <literal>binary</literal>), and the case
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of the filename doesn't matter (mount option <literal>posix=0</literal>).
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</para>
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<para>The cygdrive prefix flags are also used for all UNC paths starting with
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two slashes, unless they are accessed through a mount point. For instance,
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consider these <filename>/etc/fstab</filename> entries:</para>
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<screen>
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//server/share /mysrv ntfs posix=1,acl 0 0
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none /cygdrive cygdrive posix=0,noacl 0 0
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</screen>
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<para>Assume there's a file <filename>\\server\share\foo</filename> on the
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share. When accessing it as <filename>/mysrv/foo</filename>, then the flags
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<literal>posix=1,acl</literal> of the /mysrv mount point are used. When
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accessing it as <filename>//server/share/foo</filename>, then the flags
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for the cygdrive prefix, <literal>posix=0,noacl</literal> are used.</para>
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<note><para>This only applies to UNC paths using forward slashes. When
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using backslashes the flags for native paths are used. See
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<xref linkend="pathnames-win32"></xref>.</para></note>
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<para>The cygdrive prefix may be changed in the fstab file as outlined above.
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Please note that you must not use the cygdrive prefix for any other mount
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point. For instance this:</para>
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<screen>
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none /cygdrive cygdrive binary 0 0
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D: /cygdrive/d somefs text 0 0
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</screen>
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<para>will not make file access using the /mnt/d path prefix suddenly using
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textmode. If you want to mount any drive explicitly in another mode than
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the cygdrive prefix, use a distinct path prefix:</para>
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<screen>
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none /cygdrive cygdrive binary 0 0
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D: /mnt/d somefs text 0 0
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</screen>
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<para>To simplify scripting, Cygwin also provides a
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<filename>/proc/cygdrive</filename> symlink, which allows to use a fixed path
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in scripts, even if the actual cygdrive prefix has been changed, or is different
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between different users. So, in scripts, conveniently use the
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<filename>/proc/cygdrive</filename> symlink to successfully access files
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independently from the current cygdrive prefix:</para>
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<screen>
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$ mount -p
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Prefix Type Flags
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/mnt user binmode
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$ cat > x.sh <<EOF
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cd /proc/cygdrive/c/Windows/System32/Drivers/etc
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ls -l hosts
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EOF
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$ sh -c ./x.sh
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-rwxrwx---+ 1 SYSTEM SYSTEM 826 Sep 4 22:43 hosts
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</screen>
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</sect2>
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<sect2 id="usertemp"><title>The usertemp file system type</title>
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<para>On Windows, the environment variable <literal>TEMP</literal> specifies
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the location of the temp folder. It serves the same purpose as the /tmp/
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directory in Unix systems. In contrast to /tmp/, it is by default a
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different folder for every Windows user. By using the special purpose usertemp
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file system, that temp folder can be mapped to /tmp/. This is particularly
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useful in setups where the administrator wants to write-protect the entire
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Cygwin directory. The usertemp file system can be configured in /etc/fstab
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like this:</para>
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<screen>
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none /tmp usertemp binary,posix=0 0 0
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</screen>
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</sect2>
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<sect2 id="pathnames-symlinks"><title>Symbolic links</title>
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<para>Symbolic links are not present and supported on Windows until Windows
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Vista/Server 2008, and then only on some filesystems. Since POSIX applications
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are rightfully expecting to use symlinks and the
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<literal>symlink(2)</literal> system call, Cygwin had to find a
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workaround for this Windows flaw.</para>
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<para>Cygwin creates symbolic links potentially in multiple different
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ways:</para>
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<itemizedlist mark="bullet">
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<listitem>
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<para>The default symlinks are plain files containing a magic cookie
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followed by the path to which the link points. They are marked with the
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DOS SYSTEM attribute so that only files with that attribute have to be
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read to determine whether or not the file is a symbolic link.</para>
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<note><para>Cygwin symbolic links are using UTF-16 to encode the filename of
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the target file, to better support internationalization. Symlinks created by
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old Cygwin releases can be read just fine. However, you could run into
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problems with them if you're now using another character set than the one you
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used when creating these symlinks
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(see <xref linkend="setup-locale-problems"></xref>).
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</para></note>
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</listitem>
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<listitem>
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<para>The shortcut style symlinks are Windows <literal>.lnk</literal>
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shortcut files with a special header and the DOS READONLY attribute set.
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This symlink type is created if the environment variable
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<literal>CYGWIN</literal> (see <xref linkend="using-cygwinenv"></xref>)
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is set to contain the string <literal>winsymlinks</literal> or
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<literal>winsymlinks:lnk</literal>. On the MVFS filesystem, which does
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not support the DOS SYSTEM attribute, this is the one and only supported
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symlink type, independently from the <literal>winsymlinks</literal>
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setting.</para>
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</listitem>
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<listitem>
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<para>Native Windows symlinks are only created on Windows Vista/2008 and later,
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and only on filesystems supporting reparse points. Due to to their weird
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restrictions and behaviour, they are only created if the user
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|
explicitely requests creating them. This is done by setting the
|
|
environment variable <literal>CYGWIN</literal> to contain the string
|
|
<literal>winsymlinks:native</literal> or
|
|
<literal>winsymlinks:nativestrict</literal>. For the difference between
|
|
these two settings, see <xref linkend="using-cygwinenv"></xref>.
|
|
On AFS, native symlinks are the only supported type of symlink due to
|
|
AFS lacking support for DOS attributes. This is independent from the
|
|
<literal>winsymlinks</literal> setting.</para>
|
|
<para>Creation of native symlinks follows special rules to ensure the links
|
|
are usable outside of Cygwin. This includes dereferencing any Cygwin-only
|
|
symlinks that lie in the target path.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>On the NFS filesystem, Cygwin always creates real NFS symlinks.</para>
|
|
</listitem>
|
|
|
|
</itemizedlist>
|
|
|
|
<para>All of the above four symlink types are recognized and used as symlinks
|
|
under all circumstances. However, if the default plain file symlink type
|
|
is lacking its DOS SYSTEM bit, or if the shortcut file is lacking the DOS
|
|
READONLY attribute, they are not recognized as symlink.</para>
|
|
|
|
<para>Apart from these four types, there's also a fifth type, which is
|
|
recognized as symlink but never generated by Cygwin, directory
|
|
junctions. This is an older reparse point type, supported by Windows
|
|
since Windows 2000. Filesystem junctions on the other hand are not
|
|
handled as symlinks, since otherwise they would not be recognized as
|
|
filesystem borders by commands like <command>find -xdev</command>.</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="pathnames-win32"><title>Using native Win32 paths</title>
|
|
|
|
<para>Using native Win32 paths in Cygwin, while often possible, is generally
|
|
inadvisable. Those paths circumvent all internal integrity checking and
|
|
bypass the information given in the Cygwin mount table.</para>
|
|
|
|
<para>The following paths are treated as native Win32 paths by the
|
|
Cygwin DLL (but not necessarily by Cygwin applications):</para>
|
|
|
|
<itemizedlist spacing="compact">
|
|
<listitem>
|
|
<para>All paths starting with a drive specifier</para>
|
|
<screen>
|
|
C:\foo
|
|
C:/foo
|
|
</screen>
|
|
</listitem>
|
|
<listitem>
|
|
<para>All paths containing at least one backslash as path component</para>
|
|
<screen>
|
|
C:/foo/bar<emphasis role='bold'>\</emphasis>baz/...
|
|
</screen>
|
|
</listitem>
|
|
<listitem>
|
|
<para>UNC paths using backslashes</para>
|
|
<screen>
|
|
\\server\share\...
|
|
</screen>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>When accessing files using native Win32 paths as above, Cygwin uses a
|
|
default setting for the mount flags. All paths using DOS notation will be
|
|
treated as case insensitive, and permissions are just faked as if the
|
|
underlying drive is a FAT drive. This also applies to NTFS and other
|
|
filesystems which usually are capable of case sensitivity and storing
|
|
permissions.</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="pathnames-win32-api"><title>Using the Win32 file API in Cygwin applications</title>
|
|
|
|
<para>Special care must be taken if your application uses Win32 file API
|
|
functions like <function>CreateFile</function> to access files using
|
|
relative pathnames, or if your application uses functions like
|
|
<function>CreateProcess</function> or <function>ShellExecute</function>
|
|
to start other applications.</para>
|
|
|
|
<para>When a Cygwin application is started, the Windows idea of the current
|
|
working directory (CWD) is not necessarily the same as the Cygwin CWD.
|
|
There are a couple of restrictions in the Win32 API, which disallow certain
|
|
directories as Win32 CWD:</para>
|
|
|
|
<itemizedlist spacing="compact">
|
|
<listitem>
|
|
<para>The Windows subsystem only supports CWD paths of up to 258 chars.
|
|
This restriction doesn't apply for Cygwin processes, at least not as
|
|
long as they use the POSIX API (chdir, getcwd). This means, if a Cygwin
|
|
process has a CWD using an absolute path longer than 258 characters, the
|
|
Cygwin CWD and the Windows CWD differ.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>The Win32 API call to set the current directory,
|
|
<function>SetCurrentDirectory</function>, fails for directories for which
|
|
the user has no permissions, even if the user is an administrator. This
|
|
restriction doesn't apply for Cygwin processes, if they are running under
|
|
an administrator account.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para><function>SetCurrentDirectory</function> does not support
|
|
case-sensitive filenames.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>Last, but not least, <function>SetCurrentDirectory</function> can't
|
|
work on virtual Cygwin paths like /proc or /cygdrive. These paths only
|
|
exists in the Cygwin realm so they have no meaning to a native Win32
|
|
process.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>As long as the Cygwin CWD is usable as Windows CWD, the Cygwin and
|
|
Windows CWDs are in sync within a process. However, if the Cygwin process
|
|
changes its working directory into one of the directories which are
|
|
unusable as Windows CWD, we're in trouble. If the process uses the
|
|
Win32 API to access a file using a relative pathname, the resulting
|
|
absolute path would not match the expectations of the process. In the
|
|
worst case, the wrong files are deleted.</para>
|
|
|
|
<para>To workaround this problem, Cygwin sets the Windows CWD to a special
|
|
directory in this case. This special directory points to a virtual
|
|
filesystem within the native NT namespace (<filename>\??\PIPE\</filename>).
|
|
Since it's not a real filesystem, the deliberate effect is that a call to,
|
|
for instance, <function>CreateFile ("foo", ...);</function> will fail,
|
|
as long as the processes CWD doesn't work as Windows CWD.</para>
|
|
|
|
<para>So, in general, don't use the Win32 file API in Cygwin applications.
|
|
If you <emphasis role='bold'>really</emphasis> need to access files using
|
|
the Win32 API, or if you <emphasis role='bold'>really</emphasis> have to use
|
|
<function>CreateProcess</function> to start applications, rather than
|
|
the POSIX <function>exec(3)</function> family of functions, you have to
|
|
make sure that the Cygwin CWD is set to some directory which is valid as
|
|
Win32 CWD.</para>
|
|
|
|
</sect2>
|
|
|
|
<sect2 id="pathnames-additional"><title>Additional Path-related Information</title>
|
|
|
|
<para>The <command>cygpath</command> program provides the ability to
|
|
translate between Win32 and POSIX pathnames in shell scripts. See
|
|
<xref linkend="cygpath"></xref> for the details.</para>
|
|
|
|
<para>The <envar>HOME</envar>, <envar>PATH</envar>, and
|
|
<envar>LD_LIBRARY_PATH</envar> environment variables are automatically
|
|
converted from Win32 format to POSIX format (e.g. from
|
|
<filename>c:/cygwin\bin</filename> to <filename>/bin</filename>, if
|
|
there was a mount from that Win32 path to that POSIX path) when a Cygwin
|
|
process first starts.</para>
|
|
|
|
<para>Symbolic links can also be used to map Win32 pathnames to POSIX.
|
|
For example, the command
|
|
<command>ln -s //pollux/home/joe/data /data</command> would have about
|
|
the same effect as creating a mount point from
|
|
<filename>//pollux/home/joe/data</filename> to <filename>/data</filename>
|
|
using <command>mount</command>, except that symbolic links cannot set
|
|
the default file access mode. Other differences are that the mapping is
|
|
distributed throughout the file system and proceeds by iteratively
|
|
walking the directory tree instead of matching the longest prefix in a
|
|
kernel table. Note that symbolic links will only work on network
|
|
drives that are properly configured to support the "system" file
|
|
attribute. Many do not do so by default (the Unix Samba server does
|
|
not by default, for example).</para>
|
|
|
|
</sect2>
|
|
|
|
</sect1>
|