神马文学网chattr、lsattr
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NAME
chattr - change file attributes on a Linux second extended file systemSYNOPSIS
chattr[-RV][-vversion][mode]files...DESCRIPTION
chattrchanges the file attributes on a Linux second extended file system.The format of a symbolic mode is +-=[ASacDdIijsTtu].
The operator `+' causes the selected attributes to be added to theexisting attributes of the files; `-' causes them to be removed; and`=' causes them to be the only attributes that the files have.
The letters `acdijsuADST' select the new attributes for the files:append only (a), compressed (c), no dump (d), 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).
OPTIONS
- -R
- Recursively change attributes of directories and their contents.Symbolic links encountered during recursive directory traversals areignored.
- -V
- Be verbose with chattr's output and print the program version.
- -v version
- Set the file's version/generation number.
ATTRIBUTES
When a file with the 'A' attribute set is accessed, its atime record isnot modified. This avoids a certain amount of disk I/O for laptopsystems.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_IMMUTABLEcapability can set or clear this attribute. ///设置之后只能追加数据而不能删除
A file with the `c' attribute set is automatically compressed on the diskby the kernel. A read from this file returns uncompressed data. A write tothis file compresses data before storing them on the disk.
When a directory with the `D' attribute set is modified,the changes are written synchronously on the disk; this is equivalent tothe `dirsync' mount option applied to a subset of the files.
A file with the `d' attribute set is not candidate for backup when thedump(8)program is run. 不懂
The 'E' attribute is used by the experimental compression patches toindicate that a compressed file has a compression error. It may not beset or reset usingchattr(1),although it can be displayed bylsattr(1).
The 'I' attribute is used by the htree code to indicate that a directoryis behind indexed using hashed trees. It may not be set or reset usingchattr(1),although it can be displayed bylsattr(1).
A file with the `i' attribute cannot be modified: it cannot be deleted orrenamed, no link can be created to this file and no data can be writtento the file. Only the superuser or a process possessing theCAP_LINUX_IMMUTABLE capability can set or clear this attribute.
A file with the `j' attribute has all of its data written to the ext3journal before being written to the file itself, if the filesystem ismounted with the "data=ordered" or "data=writeback" options. When thefilesystem is mounted with the "data=journal" option all file datais already journalled and this attribute has no effect.Only the superuser or a process possessing the CAP_SYS_RESOURCEcapability can set or clear this attribute.
When a file with the `s' attribute set is deleted, its blocks are zeroed andwritten back to the disk.
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s ：當檔案設定了 s 屬性時，如果這個檔案被刪除，他將會被完全的移除出這個硬碟
空間，所以如果誤刪了，完全無法救回來了喔！
When a file with the `S' attribute set is modified,the changes are written synchronously on the disk; this is equivalent tothe `sync' mount option applied to a subset of the files.
A directory with the 'T' attribute will be deemed to be the top ofdirectory hierarchies for the purposes of the Orlov block allocator(which is used in on systems with Linux 2.5.46 or later).
A file with the 't' attribute will not have a partial block fragment atthe end of the file merged with other files (for those filesystems whichsupport tail-merging). This is necessary for applications such as LILOwhich read the filesystem directly, and which don't understand tail-mergedfiles. Note: As of this writing, the ext2 or ext3 filesystems do not(yet, except in very experimental patches) support tail-merging.
When a file with the `u' attribute set is deleted, its contents are saved.This allows the user to ask for its undeletion.
The 'X' attribute is used by the experimental compression patches toindicate that a raw contents of a compressed file can be accesseddirectly. It currently may not be set or reset usingchattr(1),although it can be displayed bylsattr(1).
The 'Z' attribute is used by the experimental compression patches toindicate a compressed file is dirty. It may not be set or reset usingchattr(1),although it can be displayed bylsattr(1).
AUTHOR
chattrwas written by Remy CardBUGS AND LIMITATIONS
The `c', 's', and `u' attributes are not honoredby the ext2 and ext3 filesystems as implemented in the current mainlineLinux kernels. These attributes may be implementedin future versions ext2 and ext3.The `j' option is only useful if the filesystem is mounted as ext3.
The `D' option is only useful on Linux kernel 2.5.19 and later.
AVAILABILITY
chattris part of the e2fsprogs package and is available fromhttp://e2fsprogs.sourceforge.net.NAME
lsattr - list file attributes on a Linux second extended file systemSYNOPSIS
lsattr[-RVadv][files...]DESCRIPTION
lsattrlists the file attributes on a second extended file system. Seechattr(1)for a description of the attributes and what they mean.OPTIONS
- -R
- Recursively list attributes of directories and their contents.
- -V
- Display the program version.
- -a
- List all files in directories, including files that start with `.'.
- -d
- List directories like other files, rather than listing their contents.
- -v
- List the file's version/generation number.
AUTHOR
lsattrwas written by Remy CardBUGS
There are none :-).AVAILABILITY
lsattris part of the e2fsprogs package and is available fromhttp://e2fsprogs.sourceforge.net.SEE ALSO
chattr(1)*****************eg***************
[root@zao2 tmp]# touch chattr_test
[root@zao2 tmp]# chattr +i chattr_test
[root@zao2 tmp]# lsattr chattr_test
-------------e- chattr_test
[root@zao2 tmp]# rm chattr_test
rm: cannot remove `chattr_test': Operation not permitted
[root@zao2 tmp]# chattr -i chattr_test
[root@zao2 tmp]# rm -f chattr_test