每天一个Linux命令 (2) chattr
chattr
chat + tr 聊 行 ？？
no
change attributes 改变属性
那么他是改变什么的属性呢？？？
在Linux里面，只有文件，所以是改变文件的属性。
chattr -RV+/-/=<属性>
-R 递归处理，将指定目录下的所有文件及子目录一并处理。
-v<版本编号> 设置文件或目录版本。
-V 显示指令执行过程。
+<属性> 开启文件或目录的该项属性。
-<属性> 关闭文件或目录的该项属性。
=<属性> 指定文件或目录的该项属性。
1.a：让文件或目录仅供附加用途。
2.b：不更新文件或目录的最后存取时间。
3.c：将文件或目录压缩后存放。
4.d：将文件或目录排除在倾倒操作之外。
5.i：不得任意更动文件或目录。
6.s：保密性删除文件或目录。
7.S：即时更新文件或目录。
8.u：预防意外删除
CHGRP(1) User Commands CHGRP(1)
NAME
chgrp - change group ownership
SYNOPSIS
chgrp [OPTION]... GROUP FILE...
chgrp [OPTION]... --reference=RFILE FILE...
DESCRIPTION
Change the group of each FILE to GROUP. With --reference,
change the group of each FILE to that of RFILE.
-c, --changes
like verbose but report only when a change is made
-f, --silent, --quiet
suppress most error messages
-v, --verbose
output a diagnostic for every file processed
--dereferenceManual page chgrp(1) line 1 (press h for help or q to quit)...skipping...
CHGRP(1) User Commands CHGRP(1)
NAME
chgrp - change group ownership
SYNOPSIS
chgrp [OPTION]... GROUP FILE...
chgrp [OPTION]... --reference=RFILE FILE...
DESCRIPTION
Change the group of each FILE to GROUP. With --reference,
change the group of each FILE to that of RFILE.
-c, --changes
like verbose but report only when a change is made
-f, --silent, --quiet
suppress most error messages
-v, --verbose
output a diagnostic for every file processed
--dereference
affect the referent of each symbolic link (this is the
default), rather than the symbolic link itself
-h, --no-dereference
affect symbolic links instead of any referenced file
(useful only on systems that can change the ownership of
a symlink)
--no-preserve-root
do not treat '/' specially (the default)
--preserve-root
fail to operate recursively on '/'
--reference=RFILE
use RFILE's group rather than specifying a GROUP value
-R, --recursive
operate on files and directories recursively
The following options modify how a hierarchy is traversed when
the -R option is also specified. If more than one is specified,
only the final one takes effect.
-H if a command line argument is a symbolic link to a direc‐
tory, traverse it
-L traverse every symbolic link to a directory encountered
-P do not traverse any symbolic links (default)
--help display this help and exit
--version
output version information and exit
EXAMPLES
chgrp staff /u
Change the group of /u to "staff".
chgrp -hR staff /u
Change the group of /u and subfiles to "staff".
GNU coreutils online help: <http://www.gnu.org/software/core‐
utils/> Report chgrp translation bugs to <http://translationpro‐
ject.org/team/>
AUTHOR
Written by David MacKenzie and Jim Meyering.
COPYRIGHT
Copyright © 2013 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute
it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
The full documentation for chgrp is maintained as a Texinfo man‐
ual. If the info and chgrp programs are properly installed at
your site, the command
info coreutils 'chgrp invocation'
should give you access to the complete manual.
GNU coreutils 8.22 April 2018 CHGRP(1)
[root@VM_0_12_centos ~]#
[root@VM_0_12_centos ~]# man chattr
CHATTR(1) General Commands Manual CHATTR(1)
NAME
chattr - change file attributes on a Linux file system
SYNOPSIS
chattr [ -RVf ] [ -v version ] [ mode ] files...
DESCRIPTION
chattr changes the file attributes on a Linux file system.
The format of a symbolic mode is +-=[aAcCdDeijsStTu].
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.
The letters 'aAcCdDeijsStTu' select the new attributes for the files: append only (a), no atime updates (A), compressed (c), no copy on write (C), no dump (d), synchronous
directory updates (D), extent format (e), immutable (i), data journalling (j), secure deletion (s), synchronous updates (S), no tail-merging (t), top of directory hierarchy
(T), and undeletable (u).
The following attributes are read-only, and may be listed by lsattr(1) but not modified by chattr: compression error (E), huge file (h), indexed directory (I), inline data
(N), compression raw access (X), and compressed dirty file (Z).
Not all flags are supported or utilized by all filesystems; refer to filesystem-specific man pages such as btrfs(5), ext4(5), and xfs(5) for more filesystem-specific details.
OPTIONS
-R Recursively change attributes of directories and their contents.
-V Be verbose with chattr's output and print the program version.
-f Suppress most error messages.
-v version
Set the file's version/generation number.
ATTRIBUTES
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.
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.
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. Note: please make sure to read the bugs and limitations section at the end of this document.
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.)
A file with the 'd' attribute set is not candidate for backup when the dump(8) program is run.
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 sub‐
set of the files.
The 'e' attribute indicates that the file is using extents for mapping the blocks on disk. It may not be removed using chattr(1).
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 chattr(1),
although it can be displayed by lsattr(1).
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 chattr(1), although it can be displayed by lsattr(1).
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 supe‐
ruser or a process possessing the CAP_LINUX_IMMUTABLE capability can set or clear this attribute.
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 chattr(1), although it can be
displayed by lsattr(1).
A file with the 'j' attribute has all of its data written to the ext3 or ext4 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.
A file with the 'N' attribute set indicates that the file has data stored inline, within the inode itself. It may not be set or reset using chattr(1), although it can be dis‐
played by lsattr(1).
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.
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.
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.
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.
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 limi‐
tations section at the end of this document.
The 'X' attribute is used by the experimental compression patches to indicate that the raw contents of a compressed file can be accessed directly. It currently may not be
set or reset using chattr(1), although it can be displayed by lsattr(1).
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 chattr(1), although it can be dis‐
played by lsattr(1).
AUTHOR
chattr was written by Remy Card <Remy.Card@linux.org>. It is currently being maintained by Theodore Ts'o <tytso@alum.mit.edu>.
BUGS AND LIMITATIONS
The 'c', 's', and 'u' attributes are not honored by the ext2, ext3, and ext4 filesystems as implemented in the current mainline Linux kernels.
The 'j' option is only useful if the filesystem is mounted as ext3 or ext4.
The 'D' option is only useful on Linux kernel 2.5.19 and later.
AVAILABILITY
chattr is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net.
SEE ALSO
lsattr(1), btrfs(5), ext4(5), xfs(5).
E2fsprogs version 1.42.9
相关链接：
每天一个Linux命令(1) cat