$ git clone https://github.com/rfjakob/cshatag.git
$ cd cshatag
$ make

GOSHATAG(1)                      User Manuals                      GOSHATAG(1)

NAME
       goshatag - tag files with sha256 hashes to detect bitrot

SYNOPSIS
       goshatag [OPTIONS] FILE [FILE...]

DESCRIPTION
       goshatag is a minimal and fast re-implementation of shatag
       (  https://github.com/maugier/shatag  ,  written  in  Python  by Maxime
       Augier)
       in a compiled language (since v2.0: Go, earlier versions: C).

       goshatag is a tool to detect silent  data  corruption.  It  writes  the
       mtime  and  the  sha256 checksum of a file into the file's extended at‐
       tributes. The filesystem needs to be mounted  with  user_xattr  enabled
       for  this to work.  When run again, it compares stored mtime and check‐
       sum. If it finds that the mtime  is  unchanged  but  the  checksum  has
       changed,  it  warns  on stderr.  In any case, the status of the file is
       printed to stdout and the stored checksum is updated.

       File statuses that appear on stdout are:
            <new>         file is missing both attributes
            <outdated>    both mtime and checksum have changed
            <ok>          both checksum and mtime stayed the same
            <timechange>  only mtime has changed, checksum stayed the same
            <corrupt>     mtime stayed the same but checksum changed

       goshatag no longer aims to be format-compatible with (c)shatag.  If you
       want  to  use  a  cshatag filesystem with goshatag, please run goshatag
       with the argument -migrate to completion at least once.  The  migration
       process can be interrupted safely.  (see the COMPATIBILITY section).

       cshatag  was written in C in 2012 and has been rewritten in Go in 2019.
       goshatag was forked in 2025.

OPTIONS
       -dry-run    don't make any changes
       -recursive  recursively process the contents of directories
       -remove     remove cshatag's xattrs from FILE
       -q          quiet mode - don't report <ok> files
       -qq         quiet2 mode - only report <corrupt> files and errors
       -fix        fix the stored sha256 on corrupt files
       -migrate    migrate from  user.shatag.{sha256,ts}  to  user.hash  (ext4
       compatibility)
       -plaintext   use  user.shatag.{sha256,ts} instead of user.hash (cshatag
       compatibility)
       -printok    print sha256 and ts for <ok> files
       -mt <num_threads>   number of threads to read files across (0 preserves
       ordering, careful going higher than 1 with spinning rust!)

EXAMPLES
       Check all regular files in the current working directory's file tree on
       an SSD across 8 threads:
       # goshatag -qq -recursive -mt 8 .
       Errors like corrupt files will be printed to stderr.  Run without "-qq"
       to see progress output.

       To remove extended attributes from all files:
       # goshatag -recursive -remove .

       To migrate from cshatag to goshatag:
       # goshatag -qq -recursive -migrate .

       To  remove  extended attributes from all files, including (c)shatag at‐
       tributes:
       # goshatag -recursive -plaintext -remove .

RETURN VALUE
       0 Success
       1 Wrong number of arguments
       2 One or more files could not be opened
       3 One or more files is not a regular file
       4 Extended attributes could not be written to one or more files
       5 At least one file was found to be corrupt
       6 More than one type of error occurred

COMPATIBILITY
       goshatag writes the extended attribute user.hash with both  the  sha256
       hash  and  the  ASCII  encoded  time,  whereas the original cshatag and
       shatag use the attribut  names  user.shatag.sha256  and  user.shatag.ts
       goshatag and cshatag use higher precision timestamps as compared to the
       shatag (python) version

AUTHORS
       somehibs <@github>
       https://github.com/somehibs/goshatag

       Jakob Unterwurzacher <[email protected]>
       https://github.com/rfjakob/cshatag

COPYRIGHT
       Copyright 2025 somehibs. MIT  License.   Copyright  2012  Jakob  Unter‐
       wurzacher. MIT License.

SEE ALSO
       cshatag(1), shatag(1), sha256sum(1), getfattr(1), setfattr(1)

Version 3.0.0                      MAY 2012                        GOSHATAG(1)