update README

1 files changed, 25 insertions, 11 deletions

diff --git a/README.rst b/README.rst
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+++ b/README.rst
@@ -2,17 +2,31 @@ tmpoverlay
 ==========
 
 tmpoverlay is a small, almost-POSIX shell script to create tmpfs-backed
-overlayfs mounts. tmpoverlay automatically detects and uses index=on and
-volatile, as well as redirect_dir and metacopy if only a single lowerdir is
-used. See tmpoverlay --help for usage information.
-
-One important thing to note is that like any other Linux mount, an overlayfs
-mount only affects new directory lookups. If a process has its current
-directory or has files open inside the mount point, it continues to access the
-original directory, not the overlaid one. Each process also has a cached root
-directory pointer, which can only be modified by chroot (internally) or
-pivot_root (globally). The pivot_root(2)_ and pivot_root(8)_ man pages should
-be fully read and understood before using tmpoverlay to overmount ``/``.
+overlayfs mounts.
+
+Features
+--------
+
+- minimal requirements (sh, mount, getopt, stat)
+
+Benefits over manually calling ``mkdir /tmp/x; mount ...``
+
+- separate tmpfs allows size limit (``tmpoverlay -t size=SIZE``)
+- upperdir and workdir automatically managed
+- tmpfs cleanup after mount so that umount frees RAM
+- synchronizes owner, permissions, and xattrs (including lowerdir ACL)
+- autodetects optimization flags (redirect_dir, metacopy, index, volatile)
+
+Overmounting notes
+------------------
+
+Like any other Linux mount, an overlayfs mount only affects new directory
+lookups. If a process has its current directory or has files open inside the
+mount point, it continues to access the original directory, not the overlaid
+one. Each process also has a cached root directory pointer, which can only be
+modified by chroot (internally) or pivot_root (globally). The pivot_root(2)_
+and pivot_root(8)_ man pages should be fully read and understood before using
+tmpoverlay to overmount ``/``.
 
 .. _pivot_root(2): https://man7.org/linux/man-pages/man2/pivot_root.2.html
 .. _pivot_root(8): https://man7.org/linux/man-pages/man8/pivot_root.8.html