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33 .\" $DragonFly: src/usr.bin/undo/undo.1,v 1.5 2008/07/16 21:38:10 dillon Exp $
39 .Nd Undo changes made to files on HAMMER filesystems
44 .Op Fl t Ar transaction-id
45 .Op Fl t Ar transaction-id
50 utility acquires an older version of the specified files and can output
51 them to stdout, generate a file with the previous contents, or generate
52 a diff to stdout. A history can also be generated.
54 The options are as follows:
55 .Bl -tag -width indent
57 Generate a unified diff from the older version to the current version.
59 Generate a unified diff from the current version to the older version.
61 Generate a single line giving the transaction id and converted timestamp
62 of the version of the file requested, rather than dumping the contents
65 Iterate through the file's entire history generating undo files, diffs,
66 output, etc. Execute the generation operation for each version.
68 Output to a file with name synthesized from the input filename postfixed with ".undo".
69 If not specified output is either to stdout or, if a single file argument
70 is given, the file specified by the
76 Output to the specified file instead of to stdout. If iterating through
77 a file's entire history
79 will be postfixed with an iteration number in the form "outfile.%04d".
80 If multiple files are specified
82 is used as a template where '%s' is replaced with the last component of
83 each file path. When used with multiple files '%%' must be used in the
85 specification to indicate a '%'. When used with a single file the
87 string is used verbatim.
88 .It Fl t Ar transaction-id
89 Specify how far to go back in time, by giving a HAMMER
90 transaction id (0x16chars). If not specified
91 the program will attempt to locate the most recent version of the
92 file(s) prior to the current version.
93 This option does not apply if
99 specification may be given when the
103 option is used, to provide two end-points for the diff. The file as-of
106 is used instead of the current version of the file.
109 .Li "undo -d mytextfile"
111 .Li "undo -o mytextfile.old mytextfile"
113 Exit status is 0 on success and 1 on error.
119 utility first appeared in
122 .An Matthew Dillon Aq dillon@backplane.com
124 HAMMER only synchronizes information to disk every 30 seconds or so and
125 a quick file create / delete is done entirely in system memory and cannot
126 be undone. This can be worked around by running
127 .Dq Ar hammer synctid Op filesystem .