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cshatag is a tool to detect silent data corruption. It is meant to run periodically and stores the SHA256 of each file as an extended attribute. See the Man Page below for details.
$ git clone https://github.com/rfjakob/cshatag.git
$ cd cshatag
$ make
CSHATAG(1) User Manuals CSHATAG(1)
NAME
cshatag - compiled shatag
SYNOPSIS
cshatag [OPTIONS] FILE [FILE...]
DESCRIPTION
cshatag 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).
cshatag is a tool to detect silent data corruption. It writes the mtime
and the sha256 checksum of a file into the file's extended attributes.
The filesystem needs to be mounted with user_xattr enabled for this to
work. When run again, it compares stored mtime and checksum. 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outdated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
cshatag aims to be format-compatible with shatag and uses the same ex‐
tended attributes (see the COMPATIBILITY section).
cshatag was written in C in 2012 and has been rewritten in Go in 2019.
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
-new-only update new files only, skip files with existing hashes
-ignore <pattern>
regular expression pattern for files to ignore.
-stats report statistics upon completion
EXAMPLES
Check all regular files in the file tree below the current working di‐
rectory:
# cshatag -qq -recursive .
Errors like corrupt files will be printed to stderr. Run without "-qq"
to see progress output.
To remove the extended attributes from all files:
# cshatag -recursive -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
130 Program interrupted with SIGTERM (CTRL+C)
COMPATIBILITY
cshatag writes the user.shatag.ts field with full integer nanosecond
precision, while python uses a double for the whole mtime and loses the
last few digits.
AUTHOR
Jakob Unterwurzacher <jakobunt@gmail.com>, https://github.com/rf‐
jakob/cshatag
COPYRIGHT
Copyright 2012 Jakob Unterwurzacher. MIT License.
SEE ALSO
shatag(1), sha256sum(1), getfattr(1), setfattr(1)
Linux MAY 2012 CSHATAG(1)