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* Revamp documentation for Cygwin 1.7, part 1.

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Corinna Vinschen
2008-07-17 11:49:45 +00:00
parent b2dab9e8bc
commit 85f1119b7b
16 changed files with 908 additions and 746 deletions
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winsup/doc/filemodes.sgml
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@@ -1,34 +1,33 @@
<sect1 id="using-filemodes"><title>File permissions</title>
<para>On Windows 9x systems, files are always readable, and Cygwin uses the
native read-only mode to determine if they are writable. Files are
<para>On FAT or FAT32 filesystems, files are always readable, and Cygwin
uses the DOS read-only attribute to determine if they are writable. Files are
considered to be executable if the filename ends with .bat, .com or .exe, or
if its content starts with #!. Consequently <command>chmod</command> can
only affect the "w" mode, it silently ignores actions involving the other
modes. This means that <command>ls -l</command>
needs to open and read files. It can thus be relatively slow.</para>
<para>Under NT, file permissions default to the same behavior as Windows
9x but there is optional functionality in Cygwin that can make file
systems behave more like on UNIX systems. This is turned on by adding
the "ntea" option to the <envar>CYGWIN</envar> environment variable.</para>
<para>On NTFS, file permissions are evaluated using the Access Control
Lists (ACLs) attached to a file. This can be switched off by using the
"noacl" option to the respective mount point in the
<filename>/etc/fstab</filename> or <filename>/etc/fstab.d/$USER</filename>
file. For more information on file permissions, see
<para>When the "ntea" feature is activated, Cygwin will start with basic
permissions as determined above, but can store POSIX file permissions in NT
Extended Attributes. This feature works quite well on NTFS partitions
because the attributes can be stored sensibly inside the normal NTFS
filesystem structure. However, on a FAT partition, NT stores extended
attributes in a flat file at the root of the partition called <filename>EA
DATA. SF</filename>. This file can grow to extremely large sizes if you
have a large number of files on the partition in question, slowing the
system to a crawl. In addition, the <filename>EA DATA. SF</filename> file
can only be deleted outside of Windows because of its "in use" status. For
these reasons, the use of NT Extended Attributes is off by default in
Cygwin. Finally, note that specifying "ntea" in <envar>CYGWIN</envar> has no
effect under Windows 9x. </para>
<!-- TODO: Put the file permission stuff from ntsec here??? -->
<para>Under NT, the test "[ -w filename]" is only true if filename is
writable across the board, e.g. <command>chmod +w filename</command>. </para>
<xref linkend="ntsec"></xref>.
</para>
<!-- TODO -->
<para>On NFS shares, file permissions are exactly the POSIX permissions
transmitted from the server using the NFSv3 protocol, if the NFS client
is the one from Microsoft's "Services For Unix", or the one built into
Windows Vista or later.
</para>
<para>Only the user and group ownership is not necessarily correct.</para>
</sect1>