mount-zip - Mount ZIP archives as FUSE file systems.

• mount-zip [options] zip-file
• mount-zip [options] zip-file mount-point
• mount-zip [options] zip-file-1 zip-file-2 ... mount-point

mount-zip mounts one or several ZIP archives as a read-only FUSE file system. It starts quickly, uses little memory, decodes encrypted files, and provides on-the-go decompression and caching for maximum efficiency.

mount-zip automatically creates the target mount point if needed. If no mount point is specified, mount-zip creates a mount point in the current working directory.

--help or -h : Print help.

--version or -V : Print program version.

-o quiet or -q : Print fewer log messages.

-o verbose or -v : Print more detailed log messages.

-o redact : Redact file names from log messages.

-o force : Continue even if the given password is wrong or missing, or if the encryption or compression method is unsupported.

-o precache : Preemptively decompress and cache the whole ZIP archive(s).

-o cache=DIR : Use a different cache directory (default is $TMPDIR or /tmp).

-o memcache : Cache the decompressed data in memory.

-o nocache : Do not cache the decompressed data.

-o encoding=CHARSET : Original encoding of file names.

-o notrim : Do not trim the base of the tree. Keep all the intermediate directories as specified in the ZIP archive(s).

-o nomerge : Do not merge multiple ZIP archives on top of each other. Instead, create a subdirectory for each ZIP archive inside the mount point.

-o nospecials : Hide special files (FIFOs, sockets, devices).

-o nosymlinks : Hide symbolic links.

-o nohardlinks : Hide hard links.

-o dmask=M : Directory permission mask in octal (default 0022).

-o fmask=M : File permission mask in octal (default 0022).

-o uid=N : Set the user ID of all the items in the mounted archive (default is current user).

-o gid=N : Set the group ID of all the items in the mounted archive (default is current group).

-o default_permissions : Use the user ID, group ID and permissions stored with each item in the archive.

-f : Foreground mode.

-d : Foreground mode with debug output.

Mount a ZIP archive:

$ mount-zip foobar.zip mnt 

The mounted ZIP archive can be explored and read using any application:

$ tree mnt mnt └── foo 0 directories, 1 file $ cat mnt/foo bar 

When finished, unmount the file system:

$ fusermount -u mnt 

• Read-only view
• Instant mounting, even with big ZIP archives
• Compression methods: deflate, bzip2
• Encryption methods: AES and legacy ZIP encryption
• Asks for decryption password if necessary
• Detects file name encoding
• Converts file names to Unicode UTF-8
• Deduplicates files in case of name collisions
• Unpacks files when reading them (on-the-go decompression)
• Supports all file types, including named sockets, FIFOs, block and character devices, symbolic links and hard links
• Supports Unix access modes and DOS file permissions
• Supports owner and group information (UID and GID)
• Supports relative and absolute paths
• Supports high precision timestamps
• Works on 32-bit and 64-bit devices
• Supports ZIP64 extensions, even on 32-bit devices:
  • Supports ZIP archives containing more than 65,535 files
  • Supports ZIP archives and files bigger than 4 GB
• Supports the following ZIP format extensions:
  • 000A PKWARE NTFS high-precision timestamps
  • 000D PKWARE Unix file type
  • 5455 Unix timestamps
  • 5855 Info-ZIP Unix extra fields (type 1)
  • 7855 Info-ZIP Unix extra fields (type 2)
  • 7875 Info-ZIP Unix extra fields (type 3): UID and GID

mount-zip is fully Unicode compliant. It converts the file names stored in the ZIP archive from their original encoding to UTF-8.

In order to interpret these file names correctly, mount-zip needs to determine their original encoding. By default mount-zip tries to guess this encoding using the detection feature provided by the ICU library. It can automatically recognize the following encodings:

• UTF-8
• CP437
• Shift JIS
• Big5
• EUC-JP
• EUC-KR
• GB18030
• ISO-2022-CN
• ISO-2022-JP
• ISO-2022-KR
• KOI8-R

For example, when mounting a ZIP containing a Shift JIS-encoded file name, the encoding is correctly detected:

$ mount-zip sjis-filename.zip mnt $ tree mnt mnt └── 新しいテキスト ドキュメント.txt 0 directories, 1 file 

This system is not foolproof, and doesn't recognize a number of popular encodings. For example, when mounting a ZIP containing file names encoded in CP866, they are interpreted as CP437 and rendered as Mojibake:

$ mount-zip cp866.zip mnt $ tree mnt mnt ├── äáΓá └── ÆѬßΓ«óδ⌐ ñ«¬π¼Ñ¡Γ.txt 0 directories, 2 files 

In this case, the user needs to explicitly specify the original file name encoding using the -o encoding mount option:

$ mount-zip -o encoding=cp866 cp866.zip mnt $ tree mnt mnt ├── Дата └── Текстовый документ.txt 0 directories, 2 files 

In case of name collision, mount-zip adds a number to deduplicate the conflicting file name:

$ unzip -l file-dir-same-name.zip Length Date Time Name --------- ---------- ----- ---- 25 2021-10-29 14:22 pet/cat 21 2021-10-29 14:22 pet 30 2021-10-29 14:22 pet/cat/fish 0 2021-10-29 14:22 pet/cat/fish/ 26 2021-10-29 14:22 pet/cat 22 2021-10-29 14:22 pet 31 2021-10-29 14:22 pet/cat/fish --------- ------- 155 7 files $ mount-zip file-dir-same-name.zip mnt $ tree -F mnt mnt ├── pet/ │   ├── cat/ │   │   ├── fish/ │   │   ├── fish (1) │   │   └── fish (2) │   ├── cat (1) │   └── cat (2) ├── pet (1) └── pet (2) 3 directories, 6 files 

Directories are never renamed. If a file is colliding with a directory, the file will be the one getting renamed.

mount-zip supports encrypted ZIP archives. It understands the legacy ZIP encryption scheme, as well as the more recent AES encryption schemes (AES-128, AES-192 and AES-256).

When mount-zip finds an encrypted file while mounting a ZIP archive, it asks for a password. If the given password does not decrypt the file, then mount-zip refuses to mount the ZIP archive and returns an error:

$ unzip -l different-encryptions.zip Archive: different-encryptions.zip Length Date Time Name --------- ---------- ----- ---- 23 2020-08-28 15:22 ClearText.txt 32 2020-08-28 15:23 Encrypted AES-128.txt 32 2020-08-28 15:23 Encrypted AES-192.txt 32 2020-08-28 15:23 Encrypted AES-256.txt 34 2020-08-28 15:23 Encrypted ZipCrypto.txt --------- ------- 153 5 files $ mount-zip different-encryptions.zip mnt Need password for File [1] '/Encrypted AES-128.txt' Password > Got it! Use the -o force option to mount an encrypted ZIP with a wrong password Cannot open File [1] '/Encrypted AES-128.txt': Wrong password provided 

Providing the correct password allows mount-zip to mount the ZIP archive and decode the files:

$ mount-zip different-encryptions.zip mnt Need password for File [1] '/Encrypted AES-128.txt' Password > Got it! Password is Ok $ tree mnt mnt ├── ClearText.txt ├── Encrypted AES-128.txt ├── Encrypted AES-192.txt ├── Encrypted AES-256.txt └── Encrypted ZipCrypto.txt 0 directories, 5 files $ md5sum mnt/* 7a542815e2c51837b3d8a8b2ebf36490 mnt/ClearText.txt 07c4edd2a55c9d5614457a21fb40aa56 mnt/Encrypted AES-128.txt e48d57930ef96ff2ad45867202d3250d mnt/Encrypted AES-192.txt ca5e064a0835d186f2f6326f88a7078f mnt/Encrypted AES-256.txt 275e8c5aed7e7ce2f32dd1e5e9ee4a5b mnt/Encrypted ZipCrypto.txt $ cat mnt/* This is not encrypted. This is encrypted with AES-128. This is encrypted with AES-192. This is encrypted with AES-256. This is encrypted with ZipCrypto. 

You can force mount-zip to mount an encrypted ZIP even without providing the right password by using the -o force option:

$ mount-zip -o force different-encryptions.zip mnt Need password for File [1] '/Encrypted AES-128.txt' Password > Got it! Continuing despite wrong password because of -o force option 

In this case, the files can be listed, but trying to open an encrypted file for which the given password doesn't work results in an I/O error:

$ tree mnt mnt ├── ClearText.txt ├── Encrypted AES-128.txt ├── Encrypted AES-192.txt ├── Encrypted AES-256.txt └── Encrypted ZipCrypto.txt 0 directories, 5 files $ md5sum mnt/* 7a542815e2c51837b3d8a8b2ebf36490 mnt/ClearText.txt md5sum: 'mnt/Encrypted AES-128.txt': Input/output error md5sum: 'mnt/Encrypted AES-192.txt': Input/output error md5sum: 'mnt/Encrypted AES-256.txt': Input/output error md5sum: 'mnt/Encrypted ZipCrypto.txt': Input/output error $ cat mnt/* This is not encrypted. cat: 'mnt/Encrypted AES-128.txt': Input/output error cat: 'mnt/Encrypted AES-192.txt': Input/output error cat: 'mnt/Encrypted AES-256.txt': Input/output error cat: 'mnt/Encrypted ZipCrypto.txt': Input/output error 

For security reasons, mount-zip doesn't allow the password to be specified on the command line. However, it is possible to pipe the password to mount-zip's standard input:

$ echo password | mount-zip different-encryptions.zip mnt Need password for File [1] '/Encrypted AES-128.txt' Password is Ok 

mount-zip shows symbolic links recorded in the ZIP archive:

$ mount-zip symlink.zip mnt $ tree mnt mnt ├── date └── symlink -> ../tmp/date 

Note that symbolic links can refer to files located outside the mounted ZIP archive. In some circumstances, these links could pose a security risk.

Symbolic links can be suppressed with the -o nosymlinks option:

$ mount-zip -o nosymlinks symlink.zip mnt Skipped Symlink [1] '/symlink' 2021-10-28 20:05:01 laptop ~/mount-zip/tests/blackbox/data (intrusive) $ tree mnt mnt └── date 0 directories, 1 file 

mount-zip shows special files (sockets, FIFOs or pipes, character and block devices) recorded in the ZIP archive:

$ mount-zip -o default_permissions pkware-specials.zip mnt $ ls -n mnt brw-rw---- 1 0 6 8, 1 Aug 3 2019 block crw--w---- 1 0 5 4, 0 Aug 3 2019 char prw-r--r-- 1 1000 1000 0 Aug 15 2019 fifo -rw-r--r-- 3 1000 1000 32 Aug 9 2019 regular srw------- 1 1000 1000 0 Aug 3 2019 socket lrwxrwxrwx 1 1000 1000 7 Aug 3 2019 symlink -> regular lrwxrwxrwx 1 1000 1000 7 Aug 25 2019 symlink2 -> regular -rw-r--r-- 3 1000 1000 32 Aug 9 2019 z-hardlink1 -rw-r--r-- 3 1000 1000 32 Aug 9 2019 z-hardlink2 brw-rw---- 1 0 6 8, 1 Aug 3 2019 z-hardlink-block crw--w---- 1 0 5 4, 0 Aug 3 2019 z-hardlink-char prw-r--r-- 1 1000 1000 0 Aug 15 2019 z-hardlink-fifo srw------- 1 1000 1000 0 Aug 3 2019 z-hardlink-socket lrwxrwxrwx 1 1000 1000 7 Aug 3 2019 z-hardlink-symlink -> regular 

Special files can be suppressed with the -o nospecials option:

$ mount-zip -o default_permissions -o nospecials pkware-specials.zip mnt Skipped Block Device [0] '/block' Skipped Character Device [1] '/char' Skipped Pipe [2] '/fifo' Skipped Socket [4] '/socket' Skipped Block Device [7] '/z-hardlink-block' Skipped Character Device [8] '/z-hardlink-char' Skipped Pipe [9] '/z-hardlink-fifo' Skipped Socket [10] '/z-hardlink-socket' $ ls -n mnt -rw-r--r-- 3 1000 1000 32 Aug 9 2019 regular lrwxrwxrwx 1 1000 1000 7 Aug 3 2019 symlink -> regular lrwxrwxrwx 1 1000 1000 7 Aug 25 2019 symlink2 -> regular -rw-r--r-- 3 1000 1000 32 Aug 9 2019 z-hardlink1 -rw-r--r-- 3 1000 1000 32 Aug 9 2019 z-hardlink2 lrwxrwxrwx 1 1000 1000 7 Aug 3 2019 z-hardlink-symlink -> regular 

mount-zip shows hard links recorded in the ZIP archive.

In this example, the three file entries 0regular, hlink1 and hlink2 point to the same inode number (2) and their reference count is 3:

$ mount-zip hlink-chain.zip mnt $ ls -ni mnt 2 -rw-r--r-- 3 0 0 10 Aug 14 2019 0regular 2 -rw-r--r-- 3 0 0 10 Aug 14 2019 hlink1 2 -rw-r--r-- 3 0 0 10 Aug 14 2019 hlink2 $ md5sum mnt/* e09c80c42fda55f9d992e59ca6b3307d mnt/0regular e09c80c42fda55f9d992e59ca6b3307d mnt/hlink1 e09c80c42fda55f9d992e59ca6b3307d mnt/hlink2 

Some tools can use the inode number to detect duplicated hard links. In this example, du only counts the size of the inode (2) once, even though there are three file entries pointing to it, and only reports 10 bytes instead of 30 bytes:

$ du -b mnt 10 mnt 

Duplicated hard links can be suppressed with the -o nohardlinks option:

$ mount-zip -o nohardlinks hlink-chain.zip mnt mount-zip: Skipped File [1] '/hlink1' mount-zip: Skipped File [2] '/hlink2' $ ls -ni mnt 2 -rw-r--r-- 1 0 0 10 Aug 14 2019 0regular 

mount-zip can show the Unix file permissions and ownership (UIDs and GIDs) as recorded in the ZIP archive when used with -o default_permissions:

$ mount-zip -o default_permissions unix-perm.zip mnt $ ls -n mnt -rw-r----- 1 1000 1000 0 Jan 5 2014 640 -rw-r---w- 1 1000 1000 0 Jan 5 2014 642 -rw-rw-rw- 1 1000 1000 0 Jan 5 2014 666 -rwsrwsr-x 1 1000 1000 0 Jan 5 2014 6775 -rwxrwxrwx 1 1000 1000 0 Jan 5 2014 777 $ md5sum mnt/* md5sum: mnt/640: Permission denied md5sum: mnt/642: Permission denied d41d8cd98f00b204e9800998ecf8427e mnt/666 d41d8cd98f00b204e9800998ecf8427e mnt/6775 d41d8cd98f00b204e9800998ecf8427e mnt/777 

mount-zip only does the minimum amount of work required to serve the requested data. When reading a compressed file, mount-zip only decompresses enough data to serve the reading application. This is called lazy or on-the-go decompression.

Accessing the beginning of a big compressed file is therefore instantaneous:

$ mount-zip 'Big One.zip' mnt $ ls -lh mnt/ -rw-rw-r-- 1 root root 6.4G Mar 26 2020 'Big One.txt' $ time head -4 'mnt/Big One.txt' We're going on a bear hunt. We're going to catch a big one. What a beautiful day! We're not scared. real 0m0.030s user 0m0.015s sys 0m0.014s 

mount-zip generally avoids caching decompressed data. If you read a compressed file several times, it is getting decompressed each time:

$ dd if='mnt/Big One.txt' of=/dev/null status=progress 6777995272 bytes (6.8 GB, 6.3 GiB) copied, 24.9395 s, 272 MB/s $ dd if='mnt/Big One.txt' of=/dev/null status=progress 6777995272 bytes (6.8 GB, 6.3 GiB) copied, 24.961 s, 272 MB/s 

But mount-zip will start caching a file if it detects that this file is getting read in a non-sequential way (ie the reading application starts jumping to different positions of the file).

For example, tail jumps to the end of the file. The first time this happens, mount-zip decompresses the whole file and caches the decompressed data (in about 13 seconds in this instance):

$ time tail -1 'mnt/Big One.txt' The End real 0m12.631s user 0m0.024s sys 0m0.656s 

A subsequent call to tail is instantaneous, because mount-zip has now cached the decompressed data:

$ time tail -1 'mnt/Big One.txt' The End real 0m0.032s user 0m0.018s sys 0m0.018s 

Decompressed data is cached in a temporary file located in the cache directory ($TMPDIR or /tmp by default). The cache directory can be changed with the -o cache=DIR option. The cache file is only created if necessary, and automatically deleted when the ZIP is unmounted.

Alternatively, the -o memcache option caches the decompressed data in memory. Be cautious with this option since it can cause mount-zip to use a lot of memory.

You can preemtively cache data at mount time by using the -o precache option. The cost of decompression in incurred upfront, and this ensures that any subsequent access to the mounted data is fast.

If mount-zip cannot create and expand the cache file, or if it was passed the -o nocache option, it will do its best using a small rolling buffer in memory. However, some data access patterns might then result in poor performance, especially if mount-zip has to repeatedly extract the same file.

mount-zip works well with large archives containing many files. For example on my laptop, a ZIP archive containing more than 70,000 files is mounted in half a second:

$ ls -lh linux-5.14.15.zip -rw-r--r-- 1 fdegros primarygroup 231M Oct 28 15:48 linux-5.14.15.zip $ time mount-zip linux-5.14.15.zip mnt real 0m0.561s user 0m0.344s sys 0m0.212s $ tree mnt mnt └── linux-5.14.15 ├── arch ... 4817 directories, 72539 files $ du -sh mnt 1.1G mnt 

The full contents of this mounted ZIP, totalling 1.1 GB, can be extracted with cp -R in 14 seconds:

$ time cp -R mnt out real 0m13.810s user 0m0.605s sys 0m5.356s 

For comparison, unzip extracts the contents of the same ZIP in 8.5 seconds:

$ time unzip -q -d out linux-5.14.15.zip real 0m8.411s user 0m6.067s sys 0m2.270s 

Mounting an 8-GB ZIP containing only a few files is instantaneous:

$ ls -lh bru.zip -rw-r----- 1 fdegros primarygroup 7.9G Sep 2 22:37 bru.zip $ time mount-zip bru.zip mnt real 0m0.033s user 0m0.018s sys 0m0.011s $ tree -h mnt mnt ├── [2.0M] bios ├── [ 25G] disk └── [ 64M] tools 0 directories, 3 files 

Decompressing and reading the 25-GB file from this mounted ZIP takes less than two minutes:

$ dd if=mnt/disk of=/dev/null status=progress 26843545600 bytes (27 GB, 25 GiB) copied, 104.586 s, 257 MB/s 

There is no lag when opening and reading the file, and only a moderate amount of memory is used. The file is getting lazily decompressed by mount-zip as it is getting read by the dd program.

mount-zip records log messages into /var/log/user.log. They can help troubleshooting issues, especially if you are facing I/O errors when reading files from the mounted ZIP.

To read mount-zip's log messages:

$ grep mount-zip /var/log/user.log | less -S 

To follow mount-zip's log messages as they are being written:

$ tail -F /var/log/user.log | grep mount-zip 

Alternatively, you can run mount-zip in foreground mode with the -f option and read all the log messages on the terminal.

By default, mount-zip writes INFO and ERROR messages. You can decrease the logging level to just ERROR messages with the -o quiet option. Or you can increase the logging level to include DEBUG messages with the -o verbose option:

$ mount-zip -f -o verbose foobar.zip mnt Indexing 'foobar.zip'... Allocating 16 buckets Detected encoding UTF-8 with 15% confidence Indexed 'foobar.zip' in 0 ms Mounted 'foobar.zip' on 'mnt' in 2 ms Reader 1: Opened File [0] Reader 1: Closed Unmounting 'foobar.zip' from 'mnt'... Unmounted 'foobar.zip' in 0 ms 

To prevent file names from being recorded in mount-zip's log messages, use the -o redact option:

$ mount-zip -f -o verbose -o redact bad-crc.zip mnt Indexing (redacted)... Allocating 16 buckets Indexed (redacted) in 0 ms Mounted (redacted) on (redacted) in 2 ms Reader 1: Opened File [0] Cannot read (redacted): Cannot read file: CRC error Reader 1: Closed Unmounting (redacted) from (redacted)... Unmounted (redacted) in 0 ms 

mount-zip returns distinct error codes for different error conditions related to the ZIP archives themselves:

0 : Success.

1 : Generic error code for: missing argument, unknown option, unknown file name encoding, mount point cannot be created, mount point is not empty, etc.

11 : An archive is a multipart ZIP.

15 : A ZIP archive cannot be read.

19 : A ZIP archive cannot be found.

21 : A ZIP archive cannot be opened.

23 : Decompression error. This is probably the sign of a wrong password. Use -o force to bypass the password verification.

26 : Unsupported compression method. Use -o force to bypass the compression method verification.

29 : An archive is not recognized as a valid ZIP.

31 : A ZIP archive has an inconsistent structure.

34 : Unsupported encryption method. Use -o force to bypass the encryption method verification.

36 : Password needed. A ZIP archive contains an encrypted file, but no password was provided. Use -o force to bypass the password verification.

37 : Wrong password. A ZIP archive contains an encrypted file, and the provided password does not decrypt it. Use -o force to bypass the password verification.

45 : Possibly truncated or corrupted ZIP archive, as detected by libzip 1.11 or higher.

mount-zip started as a fork of fuse-zip.

The original fuse-zip project was created in 2008 by Alexander Galanin and is available on Bitbucket.

The mount-zip project was then forked from fuse-zip in 2021 and further developed by François Degros. The ability to write and modify ZIP archives has been removed, but a number of optimisations and features have been added:

• François Degros
• Alexander Galanin

mount-zip is released under the GNU General Public License Version 3 or later.

fuse-archive(1), fuse-zip(1), fusermount(1), fuse(8), umount(8)