misc/chattr.1.in

   1 .\" -*- nroff -*-
   2 .TH CHATTR 1 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
   3 .SH NAME
   4 chattr \- change file attributes on a Linux second extended file system
   5 .SH SYNOPSIS
   6 .B chattr
   7 [
   8 .B \-RV
   9 ]
  10 [
  11 .B \-v
  12 .I version
  13 ]
  14 [
  15 .I mode
  16 ]
  17 .I files...
  18 .SH DESCRIPTION
  19 .B chattr
  20 changes the file attributes on a Linux second extended file system.
  21 .PP
  22 The format of a symbolic mode is +-=[ASacDdIijsTtu].
  23 .PP
  24 The operator `+' causes the selected attributes to be added to the
  25 existing attributes of the files; `-' causes them to be removed; and
  26 `=' causes them to be the only attributes that the files have.
  27 .PP
  28 The letters `ASacDdijsu' select the new attributes for the files:
  29 don't update atime (A), synchronous updates (S), synchronous directory
  30 updates (D), append only (a), compressed (c), no dump (d), immutable (i),
  31 data journalling (j), secure deletion (s), top of directory hierarchy
  32 (T), no tail-merging (t), and undeletable (u).
  33 .SH OPTIONS
  34 .TP
  35 .B \-R
  36 Recursively change attributes of directories and their contents.
  37 Symbolic links encountered during recursive directory traversals are
  38 ignored.
  39 .TP
  40 .B \-V
  41 Be verbose with chattr's output and print the program version.
  42 .TP
  43 .BI \-v " version"
  44 Set the file's version/generation number.
  45 .SH ATTRIBUTES
  46 When a file with the 'A' attribute set is accessed, its atime record is
  47 not modified.  This avoids a certain amount of disk I/O for laptop
  48 systems.
  49 .PP
  50 A file with the `a' attribute set can only be open in append mode for writing.
  51 Only the superuser or a process possessing the CAP_LINUX_IMMUTABLE
  52 capability can set or clear this attribute.
  53 .PP
  54 A file with the `c' attribute set is automatically compressed on the disk
  55 by the kernel.  A read from this file returns uncompressed data.  A write to
  56 this file compresses data before storing them on the disk.
  57 .PP
  58 When a directory with the `D' attribute set is modified,
  59 the changes are written synchronously on the disk; this is equivalent to
  60 the `dirsync' mount option applied to a subset of the files.
  61 .PP
  62 A file with the `d' attribute set is not candidate for backup when the
  63 .BR dump (8)
  64 program is run.
  65 .PP
  66 The 'E' attribute is used by the experimental compression patches to
  67 indicate that a compressed file has a compression error.  It may not be
  68 set or reset using
  69 .BR chattr (1),
  70 although it can be displayed by
  71 .BR lsattr (1).
  72 .PP
  73 The 'I' attribute is used by the htree code to indicate that a directory
  74 is behind indexed using hashed trees.  It may not be set or reset using
  75 .BR chattr (1),
  76 although it can be displayed by
  77 .BR lsattr (1).
  78 .PP
  79 A file with the `i' attribute cannot be modified: it cannot be deleted or
  80 renamed, no link can be created to this file and no data can be written
  81 to the file.  Only the superuser or a process possessing the
  82 CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
  83 .PP
  84 A file with the `j' attribute has all of its data written to the ext3
  85 journal before being written to the file itself, if the filesystem is
  86 mounted with the "data=ordered" or "data=writeback" options.  When the
  87 filesystem is mounted with the "data=journal" option all file data
  88 is already journalled and this attribute has no effect.
  89 Only the superuser or a process possessing the CAP_SYS_RESOURCE
  90 capability can set or clear this attribute.
  91 .PP
  92 When a file with the `s' attribute set is deleted, its blocks are zeroed and
  93 written back to the disk.
  94 .PP
  95 When a file with the `S' attribute set is modified,
  96 the changes are written synchronously on the disk; this is equivalent to
  97 the `sync' mount option applied to a subset of the files.
  98 .PP
  99 A directory with the 'T' attribute will be deemed to be the top of
 100 directory hierarchies for the purposes of the Orlov block allocator
 101 (which is used in on systems with Linux 2.5.46 or later).
 102 .PP
 103 A file with the 't' attribute will not have a partial block fragment at
 104 the end of the file merged with other files (for those filesystems which
 105 support tail-merging).  This is necessary for applications such as LILO
 106 which read the filesystem directly, and which don't understand tail-merged
 107 files.  Note: As of this writing, the ext2 or ext3 filesystems do not
 108 (yet, except in very experimental patches) support tail-merging.
 109 .PP
 110 When a file with the `u' attribute set is deleted, its contents are saved.
 111 This allows the user to ask for its undeletion.
 112 .PP
 113 The 'X' attribute is used by the experimental compression patches to
 114 indicate that a raw contents of a compressed file can be accessed
 115 directly.  It currently may not be set or reset using
 116 .BR chattr (1),
 117 although it can be displayed by
 118 .BR lsattr (1).
 119 .PP
 120 The 'Z' attribute is used by the experimental compression patches to
 121 indicate a compressed file is dirty.  It may not be set or reset using
 122 .BR chattr (1),
 123 although it can be displayed by
 124 .BR lsattr (1).
 125 .PP
 126 .SH AUTHOR
 127 .B chattr
 128 was written by Remy Card <Remy.Card@linux.org>.
 129 .SH BUGS AND LIMITATIONS
 130 As of Linux 2.2, the `c', 's',  and `u' attribute are not honored
 131 by the kernel filesystem code.    These attributes will be implemented
 132 in a future ext2 fs version.
 133 .PP
 134 The `j' option is only useful if the filesystem is mounted as ext3.
 135 .PP
 136 The `D' option is only useful on Linux kernel 2.5.19 and later.
 137 .SH AVAILABILITY
 138 .B chattr
 139 is part of the e2fsprogs package and is available from
 140 http://e2fsprogs.sourceforge.net.
 141 .SH SEE ALSO
 142 .BR lsattr (1)