chattr: add the -C option to the usage message

[tools/e2fsprogs.git] / misc / chattr.1.in

diff --git a/misc/chattr.1.in b/misc/chattr.1.in
index 1e17bd8..2500561 100644 (file)
--- a/misc/chattr.1.in
+++ b/misc/chattr.1.in
@@ -1,11 +1,11 @@
 .\" -*- nroff -*-
 .TH CHATTR 1 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
 .SH NAME
 .\" -*- nroff -*-
 .TH CHATTR 1 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
 .SH NAME

-chattr \- change file attributes on a Linux second extended file system
+chattr \- change file attributes on a Linux file system

 .SH SYNOPSIS
 .B chattr
 [
 .SH SYNOPSIS
 .B chattr
 [

-.B \-RV
+.B \-RVf

 ]
 [
 .B \-v
 ]
 [
 .B \-v


@@ -17,29 +17,36 @@ chattr \- change file attributes on a Linux second extended file system
 .I files...
 .SH DESCRIPTION
 .B chattr
 .I files...
 .SH DESCRIPTION
 .B chattr

-changes the file attributes on a Linux second extended file system.
+changes the file attributes on a Linux file system.

 .PP
 .PP

-The format of a symbolic mode is +-=[ASacDdisTtu].
+The format of a symbolic mode is +-=[acdeijstuADST].

 .PP
 The operator `+' causes the selected attributes to be added to the
 existing attributes of the files; `-' causes them to be removed; and
 `=' causes them to be the only attributes that the files have.
 .PP
 .PP
 The operator `+' causes the selected attributes to be added to the
 existing attributes of the files; `-' causes them to be removed; and
 `=' causes them to be the only attributes that the files have.
 .PP

-The letters `ASacDdijsu' select the new attributes for the files: 
-don't update atime (A), synchronous updates (S), synchronous directory
-updates (D), append only (a), compressed (c), no dump (d), immutable (i),
-data journalling (j), secure deletion (s), top of directory hierarchy
-(T), no tail-merging (t), and undeletable (u).
+The letters `acdeijstuADST' select the new attributes for the files:
+append only (a), compressed (c), no dump (d), extent format (e), immutable (i),
+data journalling (j), secure deletion (s), no tail-merging (t),
+undeletable (u), no atime updates (A), synchronous directory updates (D),
+synchronous updates (S), and top of directory hierarchy (T).
+.PP
+The following attributes are read-only, and may be listed by
+.BR lsattr (1)
+but not modified by chattr: huge file (h), compression error (E),
+indexed directory (I), compression raw access (X), and compressed dirty
+file (Z).

 .SH OPTIONS
 .TP
 .B \-R
 Recursively change attributes of directories and their contents.
 .SH OPTIONS
 .TP
 .B \-R
 Recursively change attributes of directories and their contents.

-Symbolic links encountered during recursive directory traversals are
-ignored.

 .TP
 .B \-V
 Be verbose with chattr's output and print the program version.
 .TP
 .TP
 .B \-V
 Be verbose with chattr's output and print the program version.
 .TP

+.B \-f
+Suppress most error messages.
+.TP

 .BI \-v " version"
 Set the file's version/generation number.
 .SH ATTRIBUTES
 .BI \-v " version"
 Set the file's version/generation number.
 .SH ATTRIBUTES


@@ -48,11 +55,23 @@ not modified.  This avoids a certain amount of disk I/O for laptop
 systems.
 .PP
 A file with the `a' attribute set can only be open in append mode for writing.
 systems.
 .PP
 A file with the `a' attribute set can only be open in append mode for writing.

-Only the superuser can set or clear this attribute.
+Only the superuser or a process possessing the CAP_LINUX_IMMUTABLE
+capability can set or clear this attribute.

 .PP
 A file with the `c' attribute set is automatically compressed on the disk
 .PP
 A file with the `c' attribute set is automatically compressed on the disk

-by the kernel. A read from this file returns uncompressed data. A write to
-this file compresses data before storing them on the disk.
+by the kernel.  A read from this file returns uncompressed data.  A write to
+this file compresses data before storing them on the disk.  Note: please
+make sure to read the bugs and limitations section at the end of this
+document.
+.PP
+A file with the 'C' attribute set will not be subject to copy-on-write
+updates.  This flag is only supported on file systems which perform
+copy-on-write.  (Note: For btrfs, the 'C' flag should be
+set on new or empty files.  If it is set on a file which already has
+data blocks, it is undefined when the blocks assigned to the file will
+be fully stable.  If the 'C' flag is set on a directory, it will have no
+effect on the directory, but new files created in that directory will
+the No_COW attribute.)

 .PP
 When a directory with the `D' attribute set is modified,
 the changes are written synchronously on the disk; this is equivalent to
 .PP
 When a directory with the `D' attribute set is modified,
 the changes are written synchronously on the disk; this is equivalent to


@@ -62,63 +81,94 @@ A file with the `d' attribute set is not candidate for backup when the
 .BR dump (8)
 program is run.
 .PP
 .BR dump (8)
 program is run.
 .PP

-The 'E' attribute is used by the experimental compression patches to 
+The 'E' attribute is used by the experimental compression patches to

 indicate that a compressed file has a compression error.  It may not be
 indicate that a compressed file has a compression error.  It may not be

-set or reset using 
+set or reset using
+.BR chattr (1),
+although it can be displayed by
+.BR lsattr (1).
+.PP
+The 'e' attribute indicates that the file is using extents for mapping
+the blocks on disk.  It may not be removed using
+.BR chattr (1).
+.PP
+The 'I' attribute is used by the htree code to indicate that a directory
+is being indexed using hashed trees.  It may not be set or reset using
+.BR chattr (1),
+although it can be displayed by
+.BR lsattr (1).
+.PP
+The 'h' attribute indicates the file is storing its blocks in units of the
+filesystem blocksize instead of in units of sectors, and means that the file
+is (or at one time was) larger than 2TB.  It may not be set or reset using

 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP
 A file with the `i' attribute cannot be modified: it cannot be deleted or
 renamed, no link can be created to this file and no data can be written
 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP
 A file with the `i' attribute cannot be modified: it cannot be deleted or
 renamed, no link can be created to this file and no data can be written

-to the file. Only the superuser can set or clear this attribute.
+to the file.  Only the superuser or a process possessing the
+CAP_LINUX_IMMUTABLE capability can set or clear this attribute.

 .PP
 A file with the `j' attribute has all of its data written to the ext3
 journal before being written to the file itself, if the filesystem is
 mounted with the "data=ordered" or "data=writeback" options.  When the
 .PP
 A file with the `j' attribute has all of its data written to the ext3
 journal before being written to the file itself, if the filesystem is
 mounted with the "data=ordered" or "data=writeback" options.  When the

-filesystem is mounted with the "data=journalled" option all file data
-is already journalled and this attribute has no effect.
+filesystem is mounted with the "data=journal" option all file data
+is already journalled and this attribute has no effect.  Only
+the superuser or a process possessing the CAP_SYS_RESOURCE
+capability can set or clear this attribute.

 .PP
 .PP

-When a file with the `s' attribute set is deleted, its blocks are zeroed and
-written back to the disk.
+When a file with the `s' attribute set is deleted, its blocks are zeroed
+and written back to the disk.  Note: please make sure to read the bugs
+and limitations section at the end of this document.

 .PP
 When a file with the `S' attribute set is modified,
 the changes are written synchronously on the disk; this is equivalent to
 the `sync' mount option applied to a subset of the files.
 .PP
 .PP
 When a file with the `S' attribute set is modified,
 the changes are written synchronously on the disk; this is equivalent to
 the `sync' mount option applied to a subset of the files.
 .PP

-A directory with the 'T' attribute will be deemed to be the top of 
-directory hierarchies for the purposes of the Orlov block allocator
-(which is used in newer kernels).
+A directory with the 'T' attribute will be deemed to be the top of
+directory hierarchies for the purposes of the Orlov block allocator.
+This is a hint to the block allocator used by ext3 and ext4 that the
+subdirectories under this directory are not related, and thus should be
+spread apart for allocation purposes.   For example it is a very good
+idea to set the 'T' attribute on the /home directory, so that /home/john
+and /home/mary are placed into separate block groups.  For directories
+where this attribute is not set, the Orlov block allocator will try to
+group subdirectories closer together where possible.

 .PP
 A file with the 't' attribute will not have a partial block fragment at
 .PP
 A file with the 't' attribute will not have a partial block fragment at

-the of the file merged with other files (for those filesystems which
-support tail-merging).  This is necessary for applications such as LILO 
-which read the filesystem directly, and who don't understand tail-merged
-files.
-.PP
-When a file with the `u' attribute set is deleted, its contents are saved.
-This allows the user to ask for its undeletion.
-.PP
-The 'X' attribute is used by the experimental compression patches to 
+the end of the file merged with other files (for those filesystems which
+support tail-merging).  This is necessary for applications such as LILO
+which read the filesystem directly, and which don't understand tail-merged
+files.  Note: As of this writing, the ext2 or ext3 filesystems do not
+(yet, except in very experimental patches) support tail-merging.
+.PP
+When a file with the `u' attribute set is deleted, its contents are
+saved.  This allows the user to ask for its undeletion.  Note: please
+make sure to read the bugs and limitations section at the end of this
+document.
+.PP
+The 'X' attribute is used by the experimental compression patches to

 indicate that a raw contents of a compressed file can be accessed
 indicate that a raw contents of a compressed file can be accessed

-directly.  It currently may not be set or reset using 
+directly.  It currently may not be set or reset using

 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP
 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP

-The 'Z' attribute is used by the experimental compression patches to 
-indicate a compressed file is dirty.  It may not be set or reset using 
+The 'Z' attribute is used by the experimental compression patches to
+indicate a compressed file is dirty.  It may not be set or reset using

 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP
 .SH AUTHOR
 .B chattr
 .BR chattr (1),
 although it can be displayed by
 .BR lsattr (1).
 .PP
 .SH AUTHOR
 .B chattr

-was written by Remy Card <Remy.Card@linux.org>.
+was written by Remy Card <Remy.Card@linux.org>.  It is currently being
+maintained by Theodore Ts'o <tytso@alum.mit.edu>.

 .SH BUGS AND LIMITATIONS
 .SH BUGS AND LIMITATIONS

-As of Linux 2.2, the `c', 's',  and `u' attribute are not honored 
-by the kernel filesystem code.    These attributes will be implemented
-in a future ext2 fs version.
+The `c', 's',  and `u' attributes are not honored
+by the ext2 and ext3 filesystems as implemented in the current mainline
+Linux kernels.

 .PP
 The `j' option is only useful if the filesystem is mounted as ext3.
 .PP
 .PP
 The `j' option is only useful if the filesystem is mounted as ext3.
 .PP