X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=misc%2Fchattr.1.in;h=92f6d7031ba76801bd934975d935a8cf6d0c9606;hb=8f92c4a2ffd342b518c3101074fe00e16b5740d0;hp=cfd4ff7d3bda88e0b23cbe789d320b1560586bf2;hpb=74becf3c0a065f8d64e07ce4d31f9fe53be91d62;p=tools%2Fe2fsprogs.git diff --git a/misc/chattr.1.in b/misc/chattr.1.in index cfd4ff7..92f6d70 100644 --- a/misc/chattr.1.in +++ b/misc/chattr.1.in @@ -1,79 +1,173 @@ .\" -*- 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 [ -.B \-RV +.B \-RVf ] [ -.B -v -version +.B \-v +.I version ] [ -mode +.I mode ] .I files... .SH DESCRIPTION .B chattr -changes the files attributes on an second extended file system. +changes the file attributes on a Linux file system. .PP -The format of a symbolic mode is +-=[Sacdisu]. +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 -The letters `Sacdisu' select the new attributes for the files: synchronous -updates (S), append only (a), compressed (c), immutable (i), no dump (d), -secure deletion (s), 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 -.I -R +.B \-R Recursively change attributes of directories and their contents. .TP -.I -V -Verbosely describe changed attributes. +.B \-V +Be verbose with chattr's output and print the program version. +.TP +.B \-f +Suppress most error messages. .TP -.I -v version -Set the files version. +.BI \-v " version" +Set the file's version/generation number. .SH ATTRIBUTES +When a file with the 'A' attribute set is accessed, its atime record is +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. - +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 -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 +When a directory with the `D' attribute set is modified, +the changes are written synchronously on the disk; this is equivalent to +the `dirsync' mount option applied to a subset of the files. +.PP A file with the `d' attribute set is not candidate for backup when the .BR dump (8) program is run. - +.PP +The 'E' attribute is used by the experimental compression patches to +indicate that a compressed file has a compression error. It may not be +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 -to the file. Only the superuser can set or clear this attribute. - -When a file with the `s' attribute set is deleted, its blocks are zeroed and -written back to the disk. - +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 +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 +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. - -When a file with the `u' attribute set is deleted, its contents is saved. -This allows the user to ask for its undeletion. +.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. +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 +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 +directly. It currently may not be set or reset using +.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 +.BR chattr (1), +although it can be displayed by +.BR lsattr (1). +.PP .SH AUTHOR .B chattr -has been written by Remy Card , the developer and maintainer -of the ext2 fs. +was written by Remy Card . It is currently being +maintained by Theodore Ts'o . .SH BUGS AND LIMITATIONS -As of ext2 fs 0.5a, the `c' and `u' attribute are not honoured by the kernel -code. +The `c', 's', and `u' attributes are not honored +by the ext2 and ext3 filesystems as implemented in the current mainline +Linux kernels. These attributes may be implemented +in future versions of the ext2 and ext3 filesystems. +.PP +The `j' option is only useful if the filesystem is mounted as ext3. .PP -These attributes will be implemented in a future ext2 fs version. +The `D' option is only useful on Linux kernel 2.5.19 and later. .SH AVAILABILITY .B chattr -is available for anonymous ftp from ftp.ibp.fr and tsx-11.mit.edu in -/pub/linux/packages/ext2fs. +is part of the e2fsprogs package and is available from +http://e2fsprogs.sourceforge.net. .SH SEE ALSO .BR lsattr (1)