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 +-=[ASacDdistu].
  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), and undeletable (u).
  32 .SH OPTIONS
  33 .TP
  34 .B \-R
  35 Recursively change attributes of directories and their contents.
  36 Symbolic links encountered during recursive directory traversals are
  37 ignored.
  38 .TP
  39 .B \-V
  40 Be verbose with chattr's output and print the program version.
  41 .TP
  42 .BI \-v " version"
  43 Set the file's version/generation number.
  44 .SH ATTRIBUTES
  45 When a file with the 'A' attribute set is accessed, its atime record is
  46 not modified.  This avoids a certain amount of disk I/O for laptop
  47 systems.
  48 .PP
  49 A file with the `a' attribute set can only be open in append mode for writing.
  50 Only the superuser can set or clear this attribute.
  51 .PP
  52 A file with the `c' attribute set is automatically compressed on the disk
  53 by the kernel. A read from this file returns uncompressed data. A write to
  54 this file compresses data before storing them on the disk.
  55 .PP
  56 When a directory with the `D' attribute set is modified,
  57 the changes are written synchronously on the disk; this is equivalent to
  58 the `dirsync' mount option applied to a subset of the files.
  59 .PP
  60 A file with the `d' attribute set is not candidate for backup when the
  61 .BR dump (8)
  62 program is run.
  63 .PP
  64 The 'E' attribute is used by the experimental compression patches to
  65 indicate that a compressed file has a compression error.  It may not be
  66 set or reset using
  67 .BR chattr (1),
  68 although it can be displayed by
  69 .BR lsattr (1).
  70 .PP
  71 A file with the `i' attribute cannot be modified: it cannot be deleted or
  72 renamed, no link can be created to this file and no data can be written
  73 to the file. Only the superuser can set or clear this attribute.
  74 .PP
  75 A file with the `j' attribute has all of its data written to the ext3
  76 journal before being written to the file itself, if the filesystem is
  77 mounted with the "data=ordered" or "data=writeback" options.  When the
  78 filesystem is mounted with the "data=journalled" option all file data
  79 is already journalled and this attribute has no effect.
  80 .PP
  81 When a file with the `s' attribute set is deleted, its blocks are zeroed and
  82 written back to the disk.
  83 .PP
  84 When a file with the `S' attribute set is modified,
  85 the changes are written synchronously on the disk; this is equivalent to
  86 the `sync' mount option applied to a subset of the files.
  87 .PP
  88 A file with the 't' attribute will not have a partial block fragment at
  89 the of the file merged with other files (for those filesystems which
  90 support tail-merging).  This is necessary for applications such as LILO
  91 which read the filesystem directly, and who don't understand tail-merged
  92 files.
  93 .PP
  94 When a file with the `u' attribute set is deleted, its contents are saved.
  95 This allows the user to ask for its undeletion.
  96 .PP
  97 The 'X' attribute is used by the experimental compression patches to
  98 indicate that a raw contents of a compressed file can be accessed
  99 directly.  It currently may not be set or reset using
 100 .BR chattr (1),
 101 although it can be displayed by
 102 .BR lsattr (1).
 103 .PP
 104 The 'Z' attribute is used by the experimental compression patches to
 105 indicate a compressed file is dirty.  It may not be set or reset using
 106 .BR chattr (1),
 107 although it can be displayed by
 108 .BR lsattr (1).
 109 .PP
 110 .SH AUTHOR
 111 .B chattr
 112 was written by Remy Card <Remy.Card@linux.org>.
 113 .SH BUGS AND LIMITATIONS
 114 As of Linux 2.2, the `c', 's',  and `u' attribute are not honored
 115 by the kernel filesystem code.    These attributes will be implemented
 116 in a future ext2 fs version.
 117 .PP
 118 The `j' option is only useful if the filesystem is mounted as ext3.
 119 .PP
 120 The `D' option is only useful on Linux kernel 2.5.19 and later.
 121 .SH AVAILABILITY
 122 .B chattr
 123 is part of the e2fsprogs package and is available from
 124 http://e2fsprogs.sourceforge.net.
 125 .SH SEE ALSO
 126 .BR lsattr (1)