diff --git a/sources/tech/20150420 Managing file and directory attributes in linux using chattr and lsattr command.md b/sources/tech/20150420 Managing file and directory attributes in linux using chattr and lsattr command.md new file mode 100644 index 0000000000..4fe935a568 --- /dev/null +++ b/sources/tech/20150420 Managing file and directory attributes in linux using chattr and lsattr command.md @@ -0,0 +1,200 @@ +Managing file & directory attributes in linux using chattr & lsattr command +================================================================================ +There are certain control attributes that may be set on a file or directory in order to allow data to be appended, to prevent it from being changed or deleted, etc. For example, you can enable attributes on a critical system file or directory so that no users, including root, can delete or change it, disallow a backup utility such as the dump command to back up a specific file or directory, and so on. These attributes can only be set on files and directories located in an ext2, ext3, or an ext4 file system + +There are two commands **lsattr** and **chattr** that are used for attribute management. The following is the list of commonly used attributes + +注：表格代码 + +++ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+

Attributes

+		 +

Description

+
+

a (append)

+		 +

Append operation is allowed on the file

+
+

A

+		 +

This attribute will not allow to update access time of a file

+
+

c (compressed)

+		 +

When this attribute is enable then file is compressed on the disk automatically

+
+

d (dump)

+		 +

File cannot be backed up using the dump command.

+
+

D

+		 +

When D attribute is set on directory then changes are stored synchronously on the disk

+
+

e (extent format)

+		 +

It shows that the file is using extents for mapping the blocks on disk

+
+

i (immutable)

+		 +

When this attribute is enable on file then we cannot be altered, renamed and delete file.

+
+

j (journaling)

+		 +

When this attribute is set then file’s data is stored in journal first then written to file.

+
+

S (synchronous)

+		 +

When this attribute is set , then changes or modifications are stored synchronously on the disk

+
+ +Different Options that can be used in chattr Command : + +- **-R** change attributes of directory and its sub-directories recursively +- **-V** Verbose output of chattr command along with version. +- **-f** Suppress most error messages. + +**Operators** that are used in chattr command to set and unset attributes + +- The ‘+’ sign is used to set attribute on the files and directories, +- The ‘-‘ sign is used to remove or unset the attribute +- The ‘=’ sign causes them to be the only attributes that the files have. + +Basic Syntax of **chattr** and **lsattr** command : + + # chattr + + # lsattr + +### Example:1 Make a file immutable using ‘i’ attribute ### + + [root@linuxtechi ~]# chattr +i dummy_data + [root@linuxtechi ~]# lsattr dummy_data + ----i----------- dummy_data + +Now try to remove and edit the File + + [root@linuxtechi ~]# rm -f dummy_data + rm: cannot remove ‘dummy_data’: Operation not permitted + + [root@linuxtechi ~]# echo "test" >> dummy_data + -bash: dummy_data: Permission denied + +### Example:2 Remove the immutable attribute ### + + [root@linuxtechi ~]# chattr -i dummy_data + [root@linuxtechi ~]# lsattr dummy_data + ---------------- dummy_data + +### Example:3 To allow only append operations on the file ### + + [root@linuxtechi ~]# chattr +a dummy_data + [root@linuxtechi ~]# lsattr dummy_data + -----a---------- dummy_data + +Now try to append the contents of fstab file in dummy_data file + + [root@linuxtechi ~]# cat /etc/fstab >> dummy_data + [root@linuxtechi ~]# + +### Example :4 Secure Directory and its sub-directories using -R option and ‘+i’ attribute. ### + +Let’s create a directory sysadmin and its subdirectories + + [root@linuxtechi ~]# mkdir sysadmin + [root@linuxtechi ~]# mkdir sysadmin/admim_{1,2,3,4,5} + [root@linuxtechi ~]# ls -l sysadmin/ + total 0 + drwxr-xr-x. 2 root root 6 Apr 19 09:50 admim_1 + drwxr-xr-x. 2 root root 6 Apr 19 09:50 admim_2 + drwxr-xr-x. 2 root root 6 Apr 19 09:50 admim_3 + drwxr-xr-x. 2 root root 6 Apr 19 09:50 admim_4 + drwxr-xr-x. 2 root root 6 Apr 19 09:50 admim_5 + +Set immutable attribute Recursively on the directory sysadmin + + [root@linuxtechi ~]# chattr -R +i sysadmin + + [root@linuxtechi ~]# lsattr -R sysadmin/ + ----i----------- sysadmin/admim_1 + sysadmin/admim_1: + ----i----------- sysadmin/admim_2 + sysadmin/admim_2: + ----i----------- sysadmin/admim_3 + sysadmin/admim_3: + ----i----------- sysadmin/admim_4 + sysadmin/admim_4: + ----i----------- sysadmin/admim_5 + sysadmin/admim_5: + [root@linuxtechi ~]# + +Now try to delete directories using rm command + + [root@linuxtechi ~]# rm -rf sysadmin + rm: cannot remove ‘sysadmin/admim_1’: Permission denied + rm: cannot remove ‘sysadmin/admim_2’: Permission denied + rm: cannot remove ‘sysadmin/admim_3’: Permission denied + rm: cannot remove ‘sysadmin/admim_4’: Permission denied + rm: cannot remove ‘sysadmin/admim_5’: Permission denied + [root@linuxtechi ~]# + +To unset the the attributes recursively use the below command + + [root@linuxtechi ~]# chattr -R -i sysadmin + +-------------------------------------------------------------------------------- + +via: http://www.linuxtechi.com/file-directory-attributes-in-linux-using-chattr-lsattr-command/ + +作者：[Pradeep Kumar][a] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创翻译，[Linux中国](http://linux.cn/) 荣誉推出 + +[a]:http://www.linuxtechi.com/author/pradeep/ \ No newline at end of file