unpack squashfs, modify, and repack

 - Unpack cmd

unsquashfs -d c12_rootfs c12_rootfs.bin

Parallel unsquashfs: Using 4 processors

274 inodes (410 blocks) to write

[==============================================================================================================================================|] 410/410 100%

created 157 files

created 51 directories

created 117 symlinks

created 0 devices

created 0 fifos

- Get squashfs information

unsquashfs -s c12_rootfs.bin

Found a valid SQUASHFS 4:0 superblock on c12_rootfs.bin.

Creation or last append time Wed Jul 25 08:41:03 2018

Filesystem size 5699.83 Kbytes (5.57 Mbytes)

Compression xz

        Dictionary size 131072

        Filters selected: arm

Block size 131072

Filesystem is exportable via NFS

Inodes are compressed

Data is compressed

Fragments are compressed

Always-use-fragments option is not specified

Xattrs are compressed

Duplicates are removed

Number of fragments 27

Number of inodes 325

Number of ids 1

-Repack again

  mksquashfs c12_rootfs c12_rootfs_mod.bin -comp xz -Xdict-size 131072 -Xbcj arm -b 131072

Parallel mksquashfs: Using 4 processors

Creating 4.0 filesystem on c12_rootfs_mod.bin, block size 131072.

[==============================================================================================================================================-] 294/294 100%

Exportable Squashfs 4.0 filesystem, xz compressed, data block size 131072

        compressed data, compressed metadata, compressed fragments, compressed xattrs

        duplicates are removed

Filesystem size 5703.36 Kbytes (5.57 Mbytes)

        25.62% of uncompressed filesystem size (22258.76 Kbytes)

Inode table size 2568 bytes (2.51 Kbytes)

        22.61% of uncompressed inode table size (11359 bytes)

Directory table size 2842 bytes (2.78 Kbytes)

        52.02% of uncompressed directory table size (5463 bytes)

Number of duplicate files found 26

Number of inodes 326

Number of files 158

Number of fragments 27

Number of symbolic links  117

Number of device nodes 0

Number of fifo nodes 0

Number of socket nodes 0

Number of directories 51

Number of ids (unique uids + gids) 1

Number of uids 1

        sun89 (1000)

Number of gids 1

        sun89 (1000)

- Compare original and modify version 

unsquashfs -s c12_rootfs.bin

Found a valid SQUASHFS 4:0 superblock on c12_rootfs.bin.

Creation or last append time Wed Jul 25 08:41:03 2018

Filesystem size 5699.83 Kbytes (5.57 Mbytes)

Compression xz

        Dictionary size 131072

        Filters selected: arm

Block size 131072

Filesystem is exportable via NFS

Inodes are compressed

Data is compressed

Fragments are compressed

Always-use-fragments option is not specified

Xattrs are compressed

Duplicates are removed

Number of fragments 27

Number of inodes 325

Number of ids 1

 

unsquashfs -s c12_rootfs_mod.bin

Found a valid SQUASHFS 4:0 superblock on c12_rootfs_mod.bin.

Creation or last append time Sun Aug 22 14:45:41 2021

Filesystem size 5703.36 Kbytes (5.57 Mbytes)

Compression xz

        Dictionary size 131072

        Filters selected: arm

Block size 131072

Filesystem is exportable via NFS

Inodes are compressed

Data is compressed

Fragments are compressed

Always-use-fragments option is not specified

Xattrs are compressed

Duplicates are removed

Number of fragments 27

Number of inodes 326

Number of ids 1