cbtm.md

WARNING

Use at your own risk as with any tool that uses xfs_db | debugfs. No warranty, express or implied.

Motivation

Hardware hosting filesystems can change. It can be nice to save & restore ctime & btime rather than always wiping file life cycle history.

There is no OS/FS-portable way to do this. (settimeofday can do ctime, but with system-disruptive time storms.) This utility fills the gap for XFS/ext4 on Linux.

Basic usage for an XFS on DEV mounted at MNT

cbtm save /MNT >MNT.stDat

This basically just saves all the statx data (which tends to compress very well if you want).

Then, sometime later, on e.g. a brand new device:

cbtm filt -qr/MNT <MNT.stDat | cbtm resto >CMDS
umount /MNT
xfs_db -x DEV <CMDS >CMDS.log 2>&1

Here, xfs_db does the hard work. NOTE: Does not yet work for ext4.

WARNING AGAIN

Note that until you become comfortable with this tool, you should look over generated CMDS and perhaps manually run just the first few against a (backed up!) FS. { While xfs_db does have a path command as well as inode and even has escape/quote-sensitive tokenization code, unfortunately it does not de-escape or de-quote things before internal use. So, one must use inode to get pathname generality. Well, or patch xfsprogs. But stat(1) does report inodes for you. }

More details

Usage:
  cbtm {SUBCMD}  [sub-command options & parameters]
where {SUBCMD} is one of:
  help     print comprehensive or per-cmd help
  save     Save all statx metadata for all paths under roots to output.
  print    Print metadata stored in input in a human-readable format.
  filter   Remove input records if source & target differ|same [bc]time.
  restore  Generate commands to restore [cb]time input

save [optional-params] [roots: string...]
  Save all statx metadata for all paths under roots to output.

  Output format is back-to-back (statx, 2B-pathLen, NUL-term path) records.
  To be more selective than full recursion on roots, you can use the output of
  find -print[0] if you like (& file=/dev/stdin to avoid temp files).
    -f=, --file=   string ""            optional input ("-"|!tty=stdin)
    -d=, --delim=  char   '\n'          input file record delimiter
    -o=, --output= string "/dev/stdout" output file
    -q, --quiet    bool   false         suppress most OS error messages

print [optional-params]
  Print metadata stored in input in a human-readable format.
    -i=, --input= string "/dev/stdin" metadata archive/backup path
    -d=, --delim= string "\t"         set delim

filter [optional-params] PCRE path patterns to *INCLUDE*
  Remove input records if source & target differ|same [bc]time.
    -i=, --input=  string     "/dev/stdin"  metadata archive/backup path
    -o=, --output= string     "/dev/stdout" output file
    -r=, --root=   string     ""            target FS root
    -q, --quiet    bool       false         do not stderr.emit mismatches
    -m=, --match=  set(Match) {}            {}=>all else: name, size,perm,
                                            owner,links,mtime,timeSame, re
    -d=, --drop=   string     ""            PCRE path pattern to EXCLUDE

restore [optional-params]
  Generate commands to restore [cb]time input
    -i=, --input= string "/dev/stdin" metadata archive/backup path
    -k=, --kind=  FSKind xfs          xfs: gen for xfs_db -x myImage
                                      ext4: gen for debugfs -w myImage