How to modify squashfs image

/**********************************************************************
 *                  How to modify squashfs image
 * 说明：
 *     本文如何使用squashfs-tools对squashfs image进行解压及合成。
 *
 *                                    2016-4-27 深圳 南山平山村 曾剑锋
 *********************************************************************/

参考文档：
    How to modify squashfs image
        https://blog.sleeplessbeastie.eu/2012/05/27/how-to-modify-squashfs-image/


You cannot modify squashfs image directly but you can uncompress it, apply changes and compress it again.
你不能直接修改squashfs镜像，当时你可以解压他，然后修改文件，最后在压缩他。

Create temporary directory and enter it:
创建暂存文件夹，并进入：
    $ mkdir squashfs-temp
    $ cd squashfs-temp

To uncompress squashfs image (into squashfs-root directory) use unsquashfs command:
解压squashfs镜像(进入squashfs-root文件夹)使用unsquashfs命令：
    $ unsquashfs /live/image/livefs.squashfs 
    Parallel unsquashfs: Using 4 processors
    79505 inodes (89340 blocks) to write

    [===========================================================-] 89340/89340 100%
    created 72260 files
    created 9630 directories
    created 7245 symlinks
    created 0 devices
    created 0 fifos

After applying required changes you can compress it using mksquashfs command:
修改完你的需求之后，重新压缩并制作squashfs镜像：
    $ mksquashfs squashfs-root/ livefs.squashfs -noappend -always-use-fragments
    Parallel mksquashfs: Using 4 processors
    Creating 4.0 filesystem on livefs.squashfs, block size 131072.
    [===========================================================|] 82095/82095 100%
    Exportable Squashfs 4.0 filesystem, gzip compressed, data block size 131072
          compressed data, compressed metadata, compressed fragments, compressed xattrs
          duplicates are removed
    Filesystem size 1191282.88 Kbytes (1163.36 Mbytes)
          46.01% of uncompressed filesystem size (2589278.95 Kbytes)
    Inode table size 905038 bytes (883.83 Kbytes)
          29.51% of uncompressed inode table size (3066958 bytes)
    Directory table size 917125 bytes (895.63 Kbytes)
          44.02% of uncompressed directory table size (2083295 bytes)
    Number of duplicate files found 9152
    Number of inodes 89135
    Number of files 72260
    Number of fragments 6406
    Number of symbolic links  7246
    Number of device nodes 0
    Number of fifo nodes 0
    Number of socket nodes 0
    Number of directories 9629
    Number of ids (unique uids + gids) 19
    Number of uids 6
          root (0)
          daemon (1)
          milosz (1000)
          kdm (106)
          libuuid (100)
          man (6)
    Number of gids 17
          root (0)
          daemon (1)
          fuse (105)
          shadow (42)
          milosz (1000)
          vboxsf (104)
          tty (5)
          crontab (102)
          mail (8)
          mlocate (107)
          ssh (108)
          messagebus (106)
          nogroup (65534)
          utmp (43)
          utempter (112)
          staff (50)
          libuuid (101)