mksquashfs

TLDR

Create a squashfs filesystem from files and directories

$ mksquashfs [path/to/source1] [path/to/source2] [filesystem.squashfs]

Create squashfs using a specific compression algorithm

$ mksquashfs [path/to/source] [filesystem.squashfs] -comp [gzip|lzo|lz4|xz|zstd]

Exclude specific files or directories

$ mksquashfs [path/to/source] [filesystem.squashfs] -e [file_or_dir1] [file_or_dir2]

Exclude files matching wildcard pattern

$ mksquashfs [path/to/source] [filesystem.squashfs] -wildcards -e "[*.gz]"

Exclude files matching regex pattern

$ mksquashfs [path/to/source] [filesystem.squashfs] -regex -e "[pattern]"

Set custom block size (default 128KB, max 1MB)

$ mksquashfs [path/to/source] [filesystem.squashfs] -b [256K]

SYNOPSIS

mksquashfs source1 [source2...] filesystem [-comp method] [-b blocksize] [-e excludes] [options]

mksquashfs creates and appends to squashfs filesystems. Squashfs is a highly compressed, read-only filesystem commonly used for live CDs, embedded systems, and application packaging (AppImage, snap).
The tool compresses files, inodes, and directories using configurable algorithms. It supports deduplication, extended attributes, and efficient storage of sparse files. Block compression allows random access to compressed data.

PARAMETERS

-comp _method_

Compression algorithm: gzip (default), lzo, lz4, xz, zstd, lzma

-b _size_

Data block size; default 128KB, maximum 1MB

-e _items_

Exclude specified files and directories

-wildcards

Enable glob pattern matching for exclusions

-regex

Use POSIX regular expressions for exclusions

-all-root

Make all files owned by root

-force-uid _user_

Override file owner user

-force-gid _group_

Override file owner group

-processors _num_

Number of compression threads

-mem _size_

Set cache memory size

-noI

Disable inode compression

-noD

Disable data compression

-noF

Disable fragment compression

-xattrs

Store extended attributes (default)

-no-xattrs

Do not store extended attributes

-tar

Read uncompressed tar archive from stdin

-quiet

Suppress verbose output

-progress

Display progress bar

CAVEATS

Squashfs filesystems are read-only and require the squashfs kernel module. Appending to existing archives may increase fragmentation. Very high compression levels significantly increase creation time. Maximum file size depends on block size configuration.

HISTORY

Squashfs was created by Phillip Lougher and first released in 2002. It was merged into the Linux kernel mainline in version 2.6.29 (2009). The filesystem is widely used in Linux distributions for live media, container images, and read-only root filesystems.