1GIT-FAST-IMPORT(1)                Git Manual                GIT-FAST-IMPORT(1)
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NAME

6       git-fast-import - Backend for fast Git data importers
7

SYNOPSIS

9       frontend | git fast-import [<options>]
10
11

DESCRIPTION

13       This program is usually not what the end user wants to run directly.
14       Most end users want to use one of the existing frontend programs, which
15       parses a specific type of foreign source and feeds the contents stored
16       there to git fast-import.
17
18       fast-import reads a mixed command/data stream from standard input and
19       writes one or more packfiles directly into the current repository. When
20       EOF is received on standard input, fast import writes out updated
21       branch and tag refs, fully updating the current repository with the
22       newly imported data.
23
24       The fast-import backend itself can import into an empty repository (one
25       that has already been initialized by git init) or incrementally update
26       an existing populated repository. Whether or not incremental imports
27       are supported from a particular foreign source depends on the frontend
28       program in use.
29

OPTIONS

31       --force
32           Force updating modified existing branches, even if doing so would
33           cause commits to be lost (as the new commit does not contain the
34           old commit).
35
36       --quiet
37           Disable the output shown by --stats, making fast-import usually be
38           silent when it is successful. However, if the import stream has
39           directives intended to show user output (e.g.  progress
40           directives), the corresponding messages will still be shown.
41
42       --stats
43           Display some basic statistics about the objects fast-import has
44           created, the packfiles they were stored into, and the memory used
45           by fast-import during this run. Showing this output is currently
46           the default, but can be disabled with --quiet.
47
48   Options for Frontends
49       --cat-blob-fd=<fd>
50           Write responses to get-mark, cat-blob, and ls queries to the file
51           descriptor <fd> instead of stdout. Allows progress output intended
52           for the end-user to be separated from other output.
53
54       --date-format=<fmt>
55           Specify the type of dates the frontend will supply to fast-import
56           within author, committer and tagger commands. See “Date Formats”
57           below for details about which formats are supported, and their
58           syntax.
59
60       --done
61           Terminate with error if there is no done command at the end of the
62           stream. This option might be useful for detecting errors that cause
63           the frontend to terminate before it has started to write a stream.
64
65   Locations of Marks Files
66       --export-marks=<file>
67           Dumps the internal marks table to <file> when complete. Marks are
68           written one per line as :markid SHA-1. Frontends can use this file
69           to validate imports after they have been completed, or to save the
70           marks table across incremental runs. As <file> is only opened and
71           truncated at checkpoint (or completion) the same path can also be
72           safely given to --import-marks.
73
74       --import-marks=<file>
75           Before processing any input, load the marks specified in <file>.
76           The input file must exist, must be readable, and must use the same
77           format as produced by --export-marks. Multiple options may be
78           supplied to import more than one set of marks. If a mark is defined
79           to different values, the last file wins.
80
81       --import-marks-if-exists=<file>
82           Like --import-marks but instead of erroring out, silently skips the
83           file if it does not exist.
84
85       --[no-]relative-marks
86           After specifying --relative-marks the paths specified with
87           --import-marks= and --export-marks= are relative to an internal
88           directory in the current repository. In git-fast-import this means
89           that the paths are relative to the .git/info/fast-import directory.
90           However, other importers may use a different location.
91
92           Relative and non-relative marks may be combined by interweaving
93           --(no-)-relative-marks with the --(import|export)-marks= options.
94
95   Performance and Compression Tuning
96       --active-branches=<n>
97           Maximum number of branches to maintain active at once. See “Memory
98           Utilization” below for details. Default is 5.
99
100       --big-file-threshold=<n>
101           Maximum size of a blob that fast-import will attempt to create a
102           delta for, expressed in bytes. The default is 512m (512 MiB). Some
103           importers may wish to lower this on systems with constrained
104           memory.
105
106       --depth=<n>
107           Maximum delta depth, for blob and tree deltification. Default is
108           50.
109
110       --export-pack-edges=<file>
111           After creating a packfile, print a line of data to <file> listing
112           the filename of the packfile and the last commit on each branch
113           that was written to that packfile. This information may be useful
114           after importing projects whose total object set exceeds the 4 GiB
115           packfile limit, as these commits can be used as edge points during
116           calls to git pack-objects.
117
118       --max-pack-size=<n>
119           Maximum size of each output packfile. The default is unlimited.
120
121       fastimport.unpackLimit
122           See git-config(1)
123

PERFORMANCE

125       The design of fast-import allows it to import large projects in a
126       minimum amount of memory usage and processing time. Assuming the
127       frontend is able to keep up with fast-import and feed it a constant
128       stream of data, import times for projects holding 10+ years of history
129       and containing 100,000+ individual commits are generally completed in
130       just 1-2 hours on quite modest (~$2,000 USD) hardware.
131
132       Most bottlenecks appear to be in foreign source data access (the source
133       just cannot extract revisions fast enough) or disk IO (fast-import
134       writes as fast as the disk will take the data). Imports will run faster
135       if the source data is stored on a different drive than the destination
136       Git repository (due to less IO contention).
137

DEVELOPMENT COST

139       A typical frontend for fast-import tends to weigh in at approximately
140       200 lines of Perl/Python/Ruby code. Most developers have been able to
141       create working importers in just a couple of hours, even though it is
142       their first exposure to fast-import, and sometimes even to Git. This is
143       an ideal situation, given that most conversion tools are throw-away
144       (use once, and never look back).
145

PARALLEL OPERATION

147       Like git push or git fetch, imports handled by fast-import are safe to
148       run alongside parallel git repack -a -d or git gc invocations, or any
149       other Git operation (including git prune, as loose objects are never
150       used by fast-import).
151
152       fast-import does not lock the branch or tag refs it is actively
153       importing. After the import, during its ref update phase, fast-import
154       tests each existing branch ref to verify the update will be a
155       fast-forward update (the commit stored in the ref is contained in the
156       new history of the commit to be written). If the update is not a
157       fast-forward update, fast-import will skip updating that ref and
158       instead prints a warning message. fast-import will always attempt to
159       update all branch refs, and does not stop on the first failure.
160
161       Branch updates can be forced with --force, but it’s recommended that
162       this only be used on an otherwise quiet repository. Using --force is
163       not necessary for an initial import into an empty repository.
164

TECHNICAL DISCUSSION

166       fast-import tracks a set of branches in memory. Any branch can be
167       created or modified at any point during the import process by sending a
168       commit command on the input stream. This design allows a frontend
169       program to process an unlimited number of branches simultaneously,
170       generating commits in the order they are available from the source
171       data. It also simplifies the frontend programs considerably.
172
173       fast-import does not use or alter the current working directory, or any
174       file within it. (It does however update the current Git repository, as
175       referenced by GIT_DIR.) Therefore an import frontend may use the
176       working directory for its own purposes, such as extracting file
177       revisions from the foreign source. This ignorance of the working
178       directory also allows fast-import to run very quickly, as it does not
179       need to perform any costly file update operations when switching
180       between branches.
181

INPUT FORMAT

183       With the exception of raw file data (which Git does not interpret) the
184       fast-import input format is text (ASCII) based. This text based format
185       simplifies development and debugging of frontend programs, especially
186       when a higher level language such as Perl, Python or Ruby is being
187       used.
188
189       fast-import is very strict about its input. Where we say SP below we
190       mean exactly one space. Likewise LF means one (and only one) linefeed
191       and HT one (and only one) horizontal tab. Supplying additional
192       whitespace characters will cause unexpected results, such as branch
193       names or file names with leading or trailing spaces in their name, or
194       early termination of fast-import when it encounters unexpected input.
195
196   Stream Comments
197       To aid in debugging frontends fast-import ignores any line that begins
198       with # (ASCII pound/hash) up to and including the line ending LF. A
199       comment line may contain any sequence of bytes that does not contain an
200       LF and therefore may be used to include any detailed debugging
201       information that might be specific to the frontend and useful when
202       inspecting a fast-import data stream.
203
204   Date Formats
205       The following date formats are supported. A frontend should select the
206       format it will use for this import by passing the format name in the
207       --date-format=<fmt> command-line option.
208
209       raw
210           This is the Git native format and is <time> SP <offutc>. It is also
211           fast-import’s default format, if --date-format was not specified.
212
213           The time of the event is specified by <time> as the number of
214           seconds since the UNIX epoch (midnight, Jan 1, 1970, UTC) and is
215           written as an ASCII decimal integer.
216
217           The local offset is specified by <offutc> as a positive or negative
218           offset from UTC. For example EST (which is 5 hours behind UTC)
219           would be expressed in <tz> by “-0500” while UTC is “+0000”. The
220           local offset does not affect <time>; it is used only as an
221           advisement to help formatting routines display the timestamp.
222
223           If the local offset is not available in the source material, use
224           “+0000”, or the most common local offset. For example many
225           organizations have a CVS repository which has only ever been
226           accessed by users who are located in the same location and time
227           zone. In this case a reasonable offset from UTC could be assumed.
228
229           Unlike the rfc2822 format, this format is very strict. Any
230           variation in formatting will cause fast-import to reject the value.
231
232       rfc2822
233           This is the standard email format as described by RFC 2822.
234
235           An example value is “Tue Feb 6 11:22:18 2007 -0500”. The Git parser
236           is accurate, but a little on the lenient side. It is the same
237           parser used by git am when applying patches received from email.
238
239           Some malformed strings may be accepted as valid dates. In some of
240           these cases Git will still be able to obtain the correct date from
241           the malformed string. There are also some types of malformed
242           strings which Git will parse wrong, and yet consider valid.
243           Seriously malformed strings will be rejected.
244
245           Unlike the raw format above, the time zone/UTC offset information
246           contained in an RFC 2822 date string is used to adjust the date
247           value to UTC prior to storage. Therefore it is important that this
248           information be as accurate as possible.
249
250           If the source material uses RFC 2822 style dates, the frontend
251           should let fast-import handle the parsing and conversion (rather
252           than attempting to do it itself) as the Git parser has been well
253           tested in the wild.
254
255           Frontends should prefer the raw format if the source material
256           already uses UNIX-epoch format, can be coaxed to give dates in that
257           format, or its format is easily convertible to it, as there is no
258           ambiguity in parsing.
259
260       now
261           Always use the current time and time zone. The literal now must
262           always be supplied for <when>.
263
264           This is a toy format. The current time and time zone of this system
265           is always copied into the identity string at the time it is being
266           created by fast-import. There is no way to specify a different time
267           or time zone.
268
269           This particular format is supplied as it’s short to implement and
270           may be useful to a process that wants to create a new commit right
271           now, without needing to use a working directory or git
272           update-index.
273
274           If separate author and committer commands are used in a commit the
275           timestamps may not match, as the system clock will be polled twice
276           (once for each command). The only way to ensure that both author
277           and committer identity information has the same timestamp is to
278           omit author (thus copying from committer) or to use a date format
279           other than now.
280
281   Commands
282       fast-import accepts several commands to update the current repository
283       and control the current import process. More detailed discussion (with
284       examples) of each command follows later.
285
286       commit
287           Creates a new branch or updates an existing branch by creating a
288           new commit and updating the branch to point at the newly created
289           commit.
290
291       tag
292           Creates an annotated tag object from an existing commit or branch.
293           Lightweight tags are not supported by this command, as they are not
294           recommended for recording meaningful points in time.
295
296       reset
297           Reset an existing branch (or a new branch) to a specific revision.
298           This command must be used to change a branch to a specific revision
299           without making a commit on it.
300
301       blob
302           Convert raw file data into a blob, for future use in a commit
303           command. This command is optional and is not needed to perform an
304           import.
305
306       checkpoint
307           Forces fast-import to close the current packfile, generate its
308           unique SHA-1 checksum and index, and start a new packfile. This
309           command is optional and is not needed to perform an import.
310
311       progress
312           Causes fast-import to echo the entire line to its own standard
313           output. This command is optional and is not needed to perform an
314           import.
315
316       done
317           Marks the end of the stream. This command is optional unless the
318           done feature was requested using the --done command-line option or
319           feature done command.
320
321       get-mark
322           Causes fast-import to print the SHA-1 corresponding to a mark to
323           the file descriptor set with --cat-blob-fd, or stdout if
324           unspecified.
325
326       cat-blob
327           Causes fast-import to print a blob in cat-file --batch format to
328           the file descriptor set with --cat-blob-fd or stdout if
329           unspecified.
330
331       ls
332           Causes fast-import to print a line describing a directory entry in
333           ls-tree format to the file descriptor set with --cat-blob-fd or
334           stdout if unspecified.
335
336       feature
337           Enable the specified feature. This requires that fast-import
338           supports the specified feature, and aborts if it does not.
339
340       option
341           Specify any of the options listed under OPTIONS that do not change
342           stream semantic to suit the frontend’s needs. This command is
343           optional and is not needed to perform an import.
344
345   commit
346       Create or update a branch with a new commit, recording one logical
347       change to the project.
348
349                   'commit' SP <ref> LF
350                   mark?
351                   original-oid?
352                   ('author' (SP <name>)? SP LT <email> GT SP <when> LF)?
353                   'committer' (SP <name>)? SP LT <email> GT SP <when> LF
354                   data
355                   ('from' SP <commit-ish> LF)?
356                   ('merge' SP <commit-ish> LF)?
357                   (filemodify | filedelete | filecopy | filerename | filedeleteall | notemodify)*
358                   LF?
359
360       where <ref> is the name of the branch to make the commit on. Typically
361       branch names are prefixed with refs/heads/ in Git, so importing the CVS
362       branch symbol RELENG-1_0 would use refs/heads/RELENG-1_0 for the value
363       of <ref>. The value of <ref> must be a valid refname in Git. As LF is
364       not valid in a Git refname, no quoting or escaping syntax is supported
365       here.
366
367       A mark command may optionally appear, requesting fast-import to save a
368       reference to the newly created commit for future use by the frontend
369       (see below for format). It is very common for frontends to mark every
370       commit they create, thereby allowing future branch creation from any
371       imported commit.
372
373       The data command following committer must supply the commit message
374       (see below for data command syntax). To import an empty commit message
375       use a 0 length data. Commit messages are free-form and are not
376       interpreted by Git. Currently they must be encoded in UTF-8, as
377       fast-import does not permit other encodings to be specified.
378
379       Zero or more filemodify, filedelete, filecopy, filerename,
380       filedeleteall and notemodify commands may be included to update the
381       contents of the branch prior to creating the commit. These commands may
382       be supplied in any order. However it is recommended that a
383       filedeleteall command precede all filemodify, filecopy, filerename and
384       notemodify commands in the same commit, as filedeleteall wipes the
385       branch clean (see below).
386
387       The LF after the command is optional (it used to be required).
388
389       author
390           An author command may optionally appear, if the author information
391           might differ from the committer information. If author is omitted
392           then fast-import will automatically use the committer’s information
393           for the author portion of the commit. See below for a description
394           of the fields in author, as they are identical to committer.
395
396       committer
397           The committer command indicates who made this commit, and when they
398           made it.
399
400           Here <name> is the person’s display name (for example “Com M
401           Itter”) and <email> is the person’s email address
402           (“cm@example.com”). LT and GT are the literal less-than (\x3c) and
403           greater-than (\x3e) symbols. These are required to delimit the
404           email address from the other fields in the line. Note that <name>
405           and <email> are free-form and may contain any sequence of bytes,
406           except LT, GT and LF. <name> is typically UTF-8 encoded.
407
408           The time of the change is specified by <when> using the date format
409           that was selected by the --date-format=<fmt> command-line option.
410           See “Date Formats” above for the set of supported formats, and
411           their syntax.
412
413       from
414           The from command is used to specify the commit to initialize this
415           branch from. This revision will be the first ancestor of the new
416           commit. The state of the tree built at this commit will begin with
417           the state at the from commit, and be altered by the content
418           modifications in this commit.
419
420           Omitting the from command in the first commit of a new branch will
421           cause fast-import to create that commit with no ancestor. This
422           tends to be desired only for the initial commit of a project. If
423           the frontend creates all files from scratch when making a new
424           branch, a merge command may be used instead of from to start the
425           commit with an empty tree. Omitting the from command on existing
426           branches is usually desired, as the current commit on that branch
427           is automatically assumed to be the first ancestor of the new
428           commit.
429
430           As LF is not valid in a Git refname or SHA-1 expression, no quoting
431           or escaping syntax is supported within <commit-ish>.
432
433           Here <commit-ish> is any of the following:
434
435           ·   The name of an existing branch already in fast-import’s
436               internal branch table. If fast-import doesn’t know the name,
437               it’s treated as a SHA-1 expression.
438
439           ·   A mark reference, :<idnum>, where <idnum> is the mark number.
440
441               The reason fast-import uses : to denote a mark reference is
442               this character is not legal in a Git branch name. The leading :
443               makes it easy to distinguish between the mark 42 (:42) and the
444               branch 42 (42 or refs/heads/42), or an abbreviated SHA-1 which
445               happened to consist only of base-10 digits.
446
447               Marks must be declared (via mark) before they can be used.
448
449           ·   A complete 40 byte or abbreviated commit SHA-1 in hex.
450
451           ·   Any valid Git SHA-1 expression that resolves to a commit. See
452               “SPECIFYING REVISIONS” in gitrevisions(7) for details.
453
454           ·   The special null SHA-1 (40 zeros) specifies that the branch is
455               to be removed.
456
457           The special case of restarting an incremental import from the
458           current branch value should be written as:
459
460                       from refs/heads/branch^0
461
462
463           The ^0 suffix is necessary as fast-import does not permit a branch
464           to start from itself, and the branch is created in memory before
465           the from command is even read from the input. Adding ^0 will force
466           fast-import to resolve the commit through Git’s revision parsing
467           library, rather than its internal branch table, thereby loading in
468           the existing value of the branch.
469
470       merge
471           Includes one additional ancestor commit. The additional ancestry
472           link does not change the way the tree state is built at this
473           commit. If the from command is omitted when creating a new branch,
474           the first merge commit will be the first ancestor of the current
475           commit, and the branch will start out with no files. An unlimited
476           number of merge commands per commit are permitted by fast-import,
477           thereby establishing an n-way merge.
478
479           Here <commit-ish> is any of the commit specification expressions
480           also accepted by from (see above).
481
482       filemodify
483           Included in a commit command to add a new file or change the
484           content of an existing file. This command has two different means
485           of specifying the content of the file.
486
487           External data format
488               The data content for the file was already supplied by a prior
489               blob command. The frontend just needs to connect it.
490
491                           'M' SP <mode> SP <dataref> SP <path> LF
492
493               Here usually <dataref> must be either a mark reference
494               (:<idnum>) set by a prior blob command, or a full 40-byte SHA-1
495               of an existing Git blob object. If <mode> is 040000` then
496               <dataref> must be the full 40-byte SHA-1 of an existing Git
497               tree object or a mark reference set with --import-marks.
498
499           Inline data format
500               The data content for the file has not been supplied yet. The
501               frontend wants to supply it as part of this modify command.
502
503                           'M' SP <mode> SP 'inline' SP <path> LF
504                           data
505
506               See below for a detailed description of the data command.
507
508           In both formats <mode> is the type of file entry, specified in
509           octal. Git only supports the following modes:
510
511           ·   100644 or 644: A normal (not-executable) file. The majority of
512               files in most projects use this mode. If in doubt, this is what
513               you want.
514
515           ·   100755 or 755: A normal, but executable, file.
516
517           ·   120000: A symlink, the content of the file will be the link
518               target.
519
520           ·   160000: A gitlink, SHA-1 of the object refers to a commit in
521               another repository. Git links can only be specified by SHA or
522               through a commit mark. They are used to implement submodules.
523
524           ·   040000: A subdirectory. Subdirectories can only be specified by
525               SHA or through a tree mark set with --import-marks.
526
527           In both formats <path> is the complete path of the file to be added
528           (if not already existing) or modified (if already existing).
529
530           A <path> string must use UNIX-style directory separators (forward
531           slash /), may contain any byte other than LF, and must not start
532           with double quote (").
533
534           A path can use C-style string quoting; this is accepted in all
535           cases and mandatory if the filename starts with double quote or
536           contains LF. In C-style quoting, the complete name should be
537           surrounded with double quotes, and any LF, backslash, or double
538           quote characters must be escaped by preceding them with a backslash
539           (e.g., "path/with\n, \\ and \" in it").
540
541           The value of <path> must be in canonical form. That is it must not:
542
543           ·   contain an empty directory component (e.g.  foo//bar is
544               invalid),
545
546           ·   end with a directory separator (e.g.  foo/ is invalid),
547
548           ·   start with a directory separator (e.g.  /foo is invalid),
549
550           ·   contain the special component .  or ..  (e.g.  foo/./bar and
551               foo/../bar are invalid).
552
553           The root of the tree can be represented by an empty string as
554           <path>.
555
556           It is recommended that <path> always be encoded using UTF-8.
557
558       filedelete
559           Included in a commit command to remove a file or recursively delete
560           an entire directory from the branch. If the file or directory
561           removal makes its parent directory empty, the parent directory will
562           be automatically removed too. This cascades up the tree until the
563           first non-empty directory or the root is reached.
564
565                       'D' SP <path> LF
566
567           here <path> is the complete path of the file or subdirectory to be
568           removed from the branch. See filemodify above for a detailed
569           description of <path>.
570
571       filecopy
572           Recursively copies an existing file or subdirectory to a different
573           location within the branch. The existing file or directory must
574           exist. If the destination exists it will be completely replaced by
575           the content copied from the source.
576
577                       'C' SP <path> SP <path> LF
578
579           here the first <path> is the source location and the second <path>
580           is the destination. See filemodify above for a detailed description
581           of what <path> may look like. To use a source path that contains SP
582           the path must be quoted.
583
584           A filecopy command takes effect immediately. Once the source
585           location has been copied to the destination any future commands
586           applied to the source location will not impact the destination of
587           the copy.
588
589       filerename
590           Renames an existing file or subdirectory to a different location
591           within the branch. The existing file or directory must exist. If
592           the destination exists it will be replaced by the source directory.
593
594                       'R' SP <path> SP <path> LF
595
596           here the first <path> is the source location and the second <path>
597           is the destination. See filemodify above for a detailed description
598           of what <path> may look like. To use a source path that contains SP
599           the path must be quoted.
600
601           A filerename command takes effect immediately. Once the source
602           location has been renamed to the destination any future commands
603           applied to the source location will create new files there and not
604           impact the destination of the rename.
605
606           Note that a filerename is the same as a filecopy followed by a
607           filedelete of the source location. There is a slight performance
608           advantage to using filerename, but the advantage is so small that
609           it is never worth trying to convert a delete/add pair in source
610           material into a rename for fast-import. This filerename command is
611           provided just to simplify frontends that already have rename
612           information and don’t want bother with decomposing it into a
613           filecopy followed by a filedelete.
614
615       filedeleteall
616           Included in a commit command to remove all files (and also all
617           directories) from the branch. This command resets the internal
618           branch structure to have no files in it, allowing the frontend to
619           subsequently add all interesting files from scratch.
620
621                       'deleteall' LF
622
623           This command is extremely useful if the frontend does not know (or
624           does not care to know) what files are currently on the branch, and
625           therefore cannot generate the proper filedelete commands to update
626           the content.
627
628           Issuing a filedeleteall followed by the needed filemodify commands
629           to set the correct content will produce the same results as sending
630           only the needed filemodify and filedelete commands. The
631           filedeleteall approach may however require fast-import to use
632           slightly more memory per active branch (less than 1 MiB for even
633           most large projects); so frontends that can easily obtain only the
634           affected paths for a commit are encouraged to do so.
635
636       notemodify
637           Included in a commit <notes_ref> command to add a new note
638           annotating a <commit-ish> or change this annotation contents.
639           Internally it is similar to filemodify 100644 on <commit-ish> path
640           (maybe split into subdirectories). It’s not advised to use any
641           other commands to write to the <notes_ref> tree except
642           filedeleteall to delete all existing notes in this tree. This
643           command has two different means of specifying the content of the
644           note.
645
646           External data format
647               The data content for the note was already supplied by a prior
648               blob command. The frontend just needs to connect it to the
649               commit that is to be annotated.
650
651                           'N' SP <dataref> SP <commit-ish> LF
652
653               Here <dataref> can be either a mark reference (:<idnum>) set by
654               a prior blob command, or a full 40-byte SHA-1 of an existing
655               Git blob object.
656
657           Inline data format
658               The data content for the note has not been supplied yet. The
659               frontend wants to supply it as part of this modify command.
660
661                           'N' SP 'inline' SP <commit-ish> LF
662                           data
663
664               See below for a detailed description of the data command.
665
666           In both formats <commit-ish> is any of the commit specification
667           expressions also accepted by from (see above).
668
669   mark
670       Arranges for fast-import to save a reference to the current object,
671       allowing the frontend to recall this object at a future point in time,
672       without knowing its SHA-1. Here the current object is the object
673       creation command the mark command appears within. This can be commit,
674       tag, and blob, but commit is the most common usage.
675
676                   'mark' SP ':' <idnum> LF
677
678       where <idnum> is the number assigned by the frontend to this mark. The
679       value of <idnum> is expressed as an ASCII decimal integer. The value 0
680       is reserved and cannot be used as a mark. Only values greater than or
681       equal to 1 may be used as marks.
682
683       New marks are created automatically. Existing marks can be moved to
684       another object simply by reusing the same <idnum> in another mark
685       command.
686
687   original-oid
688       Provides the name of the object in the original source control system.
689       fast-import will simply ignore this directive, but filter processes
690       which operate on and modify the stream before feeding to fast-import
691       may have uses for this information
692
693                   'original-oid' SP <object-identifier> LF
694
695       where <object-identifer> is any string not containing LF.
696
697   tag
698       Creates an annotated tag referring to a specific commit. To create
699       lightweight (non-annotated) tags see the reset command below.
700
701                   'tag' SP <name> LF
702                   'from' SP <commit-ish> LF
703                   original-oid?
704                   'tagger' (SP <name>)? SP LT <email> GT SP <when> LF
705                   data
706
707       where <name> is the name of the tag to create.
708
709       Tag names are automatically prefixed with refs/tags/ when stored in
710       Git, so importing the CVS branch symbol RELENG-1_0-FINAL would use just
711       RELENG-1_0-FINAL for <name>, and fast-import will write the
712       corresponding ref as refs/tags/RELENG-1_0-FINAL.
713
714       The value of <name> must be a valid refname in Git and therefore may
715       contain forward slashes. As LF is not valid in a Git refname, no
716       quoting or escaping syntax is supported here.
717
718       The from command is the same as in the commit command; see above for
719       details.
720
721       The tagger command uses the same format as committer within commit;
722       again see above for details.
723
724       The data command following tagger must supply the annotated tag message
725       (see below for data command syntax). To import an empty tag message use
726       a 0 length data. Tag messages are free-form and are not interpreted by
727       Git. Currently they must be encoded in UTF-8, as fast-import does not
728       permit other encodings to be specified.
729
730       Signing annotated tags during import from within fast-import is not
731       supported. Trying to include your own PGP/GPG signature is not
732       recommended, as the frontend does not (easily) have access to the
733       complete set of bytes which normally goes into such a signature. If
734       signing is required, create lightweight tags from within fast-import
735       with reset, then create the annotated versions of those tags offline
736       with the standard git tag process.
737
738   reset
739       Creates (or recreates) the named branch, optionally starting from a
740       specific revision. The reset command allows a frontend to issue a new
741       from command for an existing branch, or to create a new branch from an
742       existing commit without creating a new commit.
743
744                   'reset' SP <ref> LF
745                   ('from' SP <commit-ish> LF)?
746                   LF?
747
748       For a detailed description of <ref> and <commit-ish> see above under
749       commit and from.
750
751       The LF after the command is optional (it used to be required).
752
753       The reset command can also be used to create lightweight
754       (non-annotated) tags. For example:
755
756           reset refs/tags/938
757           from :938
758
759       would create the lightweight tag refs/tags/938 referring to whatever
760       commit mark :938 references.
761
762   blob
763       Requests writing one file revision to the packfile. The revision is not
764       connected to any commit; this connection must be formed in a subsequent
765       commit command by referencing the blob through an assigned mark.
766
767                   'blob' LF
768                   mark?
769                   original-oid?
770                   data
771
772       The mark command is optional here as some frontends have chosen to
773       generate the Git SHA-1 for the blob on their own, and feed that
774       directly to commit. This is typically more work than it’s worth
775       however, as marks are inexpensive to store and easy to use.
776
777   data
778       Supplies raw data (for use as blob/file content, commit messages, or
779       annotated tag messages) to fast-import. Data can be supplied using an
780       exact byte count or delimited with a terminating line. Real frontends
781       intended for production-quality conversions should always use the exact
782       byte count format, as it is more robust and performs better. The
783       delimited format is intended primarily for testing fast-import.
784
785       Comment lines appearing within the <raw> part of data commands are
786       always taken to be part of the body of the data and are therefore never
787       ignored by fast-import. This makes it safe to import any file/message
788       content whose lines might start with #.
789
790       Exact byte count format
791           The frontend must specify the number of bytes of data.
792
793                       'data' SP <count> LF
794                       <raw> LF?
795
796           where <count> is the exact number of bytes appearing within <raw>.
797           The value of <count> is expressed as an ASCII decimal integer. The
798           LF on either side of <raw> is not included in <count> and will not
799           be included in the imported data.
800
801           The LF after <raw> is optional (it used to be required) but
802           recommended. Always including it makes debugging a fast-import
803           stream easier as the next command always starts in column 0 of the
804           next line, even if <raw> did not end with an LF.
805
806       Delimited format
807           A delimiter string is used to mark the end of the data. fast-import
808           will compute the length by searching for the delimiter. This format
809           is primarily useful for testing and is not recommended for real
810           data.
811
812                       'data' SP '<<' <delim> LF
813                       <raw> LF
814                       <delim> LF
815                       LF?
816
817           where <delim> is the chosen delimiter string. The string <delim>
818           must not appear on a line by itself within <raw>, as otherwise
819           fast-import will think the data ends earlier than it really does.
820           The LF immediately trailing <raw> is part of <raw>. This is one of
821           the limitations of the delimited format, it is impossible to supply
822           a data chunk which does not have an LF as its last byte.
823
824           The LF after <delim> LF is optional (it used to be required).
825
826   checkpoint
827       Forces fast-import to close the current packfile, start a new one, and
828       to save out all current branch refs, tags and marks.
829
830                   'checkpoint' LF
831                   LF?
832
833       Note that fast-import automatically switches packfiles when the current
834       packfile reaches --max-pack-size, or 4 GiB, whichever limit is smaller.
835       During an automatic packfile switch fast-import does not update the
836       branch refs, tags or marks.
837
838       As a checkpoint can require a significant amount of CPU time and disk
839       IO (to compute the overall pack SHA-1 checksum, generate the
840       corresponding index file, and update the refs) it can easily take
841       several minutes for a single checkpoint command to complete.
842
843       Frontends may choose to issue checkpoints during extremely large and
844       long running imports, or when they need to allow another Git process
845       access to a branch. However given that a 30 GiB Subversion repository
846       can be loaded into Git through fast-import in about 3 hours, explicit
847       checkpointing may not be necessary.
848
849       The LF after the command is optional (it used to be required).
850
851   progress
852       Causes fast-import to print the entire progress line unmodified to its
853       standard output channel (file descriptor 1) when the command is
854       processed from the input stream. The command otherwise has no impact on
855       the current import, or on any of fast-import’s internal state.
856
857                   'progress' SP <any> LF
858                   LF?
859
860       The <any> part of the command may contain any sequence of bytes that
861       does not contain LF. The LF after the command is optional. Callers may
862       wish to process the output through a tool such as sed to remove the
863       leading part of the line, for example:
864
865           frontend | git fast-import | sed 's/^progress //'
866
867       Placing a progress command immediately after a checkpoint will inform
868       the reader when the checkpoint has been completed and it can safely
869       access the refs that fast-import updated.
870
871   get-mark
872       Causes fast-import to print the SHA-1 corresponding to a mark to stdout
873       or to the file descriptor previously arranged with the --cat-blob-fd
874       argument. The command otherwise has no impact on the current import;
875       its purpose is to retrieve SHA-1s that later commits might want to
876       refer to in their commit messages.
877
878                   'get-mark' SP ':' <idnum> LF
879
880       This command can be used anywhere in the stream that comments are
881       accepted. In particular, the get-mark command can be used in the middle
882       of a commit but not in the middle of a data command.
883
884       See “Responses To Commands” below for details about how to read this
885       output safely.
886
887   cat-blob
888       Causes fast-import to print a blob to a file descriptor previously
889       arranged with the --cat-blob-fd argument. The command otherwise has no
890       impact on the current import; its main purpose is to retrieve blobs
891       that may be in fast-import’s memory but not accessible from the target
892       repository.
893
894                   'cat-blob' SP <dataref> LF
895
896       The <dataref> can be either a mark reference (:<idnum>) set previously
897       or a full 40-byte SHA-1 of a Git blob, preexisting or ready to be
898       written.
899
900       Output uses the same format as git cat-file --batch:
901
902           <sha1> SP 'blob' SP <size> LF
903           <contents> LF
904
905       This command can be used anywhere in the stream that comments are
906       accepted. In particular, the cat-blob command can be used in the middle
907       of a commit but not in the middle of a data command.
908
909       See “Responses To Commands” below for details about how to read this
910       output safely.
911
912   ls
913       Prints information about the object at a path to a file descriptor
914       previously arranged with the --cat-blob-fd argument. This allows
915       printing a blob from the active commit (with cat-blob) or copying a
916       blob or tree from a previous commit for use in the current one (with
917       filemodify).
918
919       The ls command can be used anywhere in the stream that comments are
920       accepted, including the middle of a commit.
921
922       Reading from the active commit
923           This form can only be used in the middle of a commit. The path
924           names a directory entry within fast-import’s active commit. The
925           path must be quoted in this case.
926
927                       'ls' SP <path> LF
928
929       Reading from a named tree
930           The <dataref> can be a mark reference (:<idnum>) or the full
931           40-byte SHA-1 of a Git tag, commit, or tree object, preexisting or
932           waiting to be written. The path is relative to the top level of the
933           tree named by <dataref>.
934
935                       'ls' SP <dataref> SP <path> LF
936
937       See filemodify above for a detailed description of <path>.
938
939       Output uses the same format as git ls-tree <tree> -- <path>:
940
941           <mode> SP ('blob' | 'tree' | 'commit') SP <dataref> HT <path> LF
942
943       The <dataref> represents the blob, tree, or commit object at <path> and
944       can be used in later get-mark, cat-blob, filemodify, or ls commands.
945
946       If there is no file or subtree at that path, git fast-import will
947       instead report
948
949           missing SP <path> LF
950
951       See “Responses To Commands” below for details about how to read this
952       output safely.
953
954   feature
955       Require that fast-import supports the specified feature, or abort if it
956       does not.
957
958                   'feature' SP <feature> ('=' <argument>)? LF
959
960       The <feature> part of the command may be any one of the following:
961
962       date-format, export-marks, relative-marks, no-relative-marks, force
963           Act as though the corresponding command-line option with a leading
964           -- was passed on the command line (see OPTIONS, above).
965
966       import-marks, import-marks-if-exists
967           Like --import-marks except in two respects: first, only one
968           "feature import-marks" or "feature import-marks-if-exists" command
969           is allowed per stream; second, an --import-marks= or
970           --import-marks-if-exists command-line option overrides any of these
971           "feature" commands in the stream; third, "feature
972           import-marks-if-exists" like a corresponding command-line option
973           silently skips a nonexistent file.
974
975       get-mark, cat-blob, ls
976           Require that the backend support the get-mark, cat-blob, or ls
977           command respectively. Versions of fast-import not supporting the
978           specified command will exit with a message indicating so. This lets
979           the import error out early with a clear message, rather than
980           wasting time on the early part of an import before the unsupported
981           command is detected.
982
983       notes
984           Require that the backend support the notemodify (N) subcommand to
985           the commit command. Versions of fast-import not supporting notes
986           will exit with a message indicating so.
987
988       done
989           Error out if the stream ends without a done command. Without this
990           feature, errors causing the frontend to end abruptly at a
991           convenient point in the stream can go undetected. This may occur,
992           for example, if an import front end dies in mid-operation without
993           emitting SIGTERM or SIGKILL at its subordinate git fast-import
994           instance.
995
996   option
997       Processes the specified option so that git fast-import behaves in a way
998       that suits the frontend’s needs. Note that options specified by the
999       frontend are overridden by any options the user may specify to git
1000       fast-import itself.
1001
1002               'option' SP <option> LF
1003
1004       The <option> part of the command may contain any of the options listed
1005       in the OPTIONS section that do not change import semantics, without the
1006       leading -- and is treated in the same way.
1007
1008       Option commands must be the first commands on the input (not counting
1009       feature commands), to give an option command after any non-option
1010       command is an error.
1011
1012       The following command-line options change import semantics and may
1013       therefore not be passed as option:
1014
1015       ·   date-format
1016
1017       ·   import-marks
1018
1019       ·   export-marks
1020
1021       ·   cat-blob-fd
1022
1023       ·   force
1024
1025   done
1026       If the done feature is not in use, treated as if EOF was read. This can
1027       be used to tell fast-import to finish early.
1028
1029       If the --done command-line option or feature done command is in use,
1030       the done command is mandatory and marks the end of the stream.
1031

RESPONSES TO COMMANDS

1033       New objects written by fast-import are not available immediately. Most
1034       fast-import commands have no visible effect until the next checkpoint
1035       (or completion). The frontend can send commands to fill fast-import’s
1036       input pipe without worrying about how quickly they will take effect,
1037       which improves performance by simplifying scheduling.
1038
1039       For some frontends, though, it is useful to be able to read back data
1040       from the current repository as it is being updated (for example when
1041       the source material describes objects in terms of patches to be applied
1042       to previously imported objects). This can be accomplished by connecting
1043       the frontend and fast-import via bidirectional pipes:
1044
1045           mkfifo fast-import-output
1046           frontend <fast-import-output |
1047           git fast-import >fast-import-output
1048
1049       A frontend set up this way can use progress, get-mark, ls, and cat-blob
1050       commands to read information from the import in progress.
1051
1052       To avoid deadlock, such frontends must completely consume any pending
1053       output from progress, ls, get-mark, and cat-blob before performing
1054       writes to fast-import that might block.
1055

CRASH REPORTS

1057       If fast-import is supplied invalid input it will terminate with a
1058       non-zero exit status and create a crash report in the top level of the
1059       Git repository it was importing into. Crash reports contain a snapshot
1060       of the internal fast-import state as well as the most recent commands
1061       that lead up to the crash.
1062
1063       All recent commands (including stream comments, file changes and
1064       progress commands) are shown in the command history within the crash
1065       report, but raw file data and commit messages are excluded from the
1066       crash report. This exclusion saves space within the report file and
1067       reduces the amount of buffering that fast-import must perform during
1068       execution.
1069
1070       After writing a crash report fast-import will close the current
1071       packfile and export the marks table. This allows the frontend developer
1072       to inspect the repository state and resume the import from the point
1073       where it crashed. The modified branches and tags are not updated during
1074       a crash, as the import did not complete successfully. Branch and tag
1075       information can be found in the crash report and must be applied
1076       manually if the update is needed.
1077
1078       An example crash:
1079
1080           $ cat >in <<END_OF_INPUT
1081           # my very first test commit
1082           commit refs/heads/master
1083           committer Shawn O. Pearce <spearce> 19283 -0400
1084           # who is that guy anyway?
1085           data <<EOF
1086           this is my commit
1087           EOF
1088           M 644 inline .gitignore
1089           data <<EOF
1090           .gitignore
1091           EOF
1092           M 777 inline bob
1093           END_OF_INPUT
1094
1095           $ git fast-import <in
1096           fatal: Corrupt mode: M 777 inline bob
1097           fast-import: dumping crash report to .git/fast_import_crash_8434
1098
1099           $ cat .git/fast_import_crash_8434
1100           fast-import crash report:
1101               fast-import process: 8434
1102               parent process     : 1391
1103               at Sat Sep 1 00:58:12 2007
1104
1105           fatal: Corrupt mode: M 777 inline bob
1106
1107           Most Recent Commands Before Crash
1108           ---------------------------------
1109             # my very first test commit
1110             commit refs/heads/master
1111             committer Shawn O. Pearce <spearce> 19283 -0400
1112             # who is that guy anyway?
1113             data <<EOF
1114             M 644 inline .gitignore
1115             data <<EOF
1116           * M 777 inline bob
1117
1118           Active Branch LRU
1119           -----------------
1120               active_branches = 1 cur, 5 max
1121
1122           pos  clock name
1123           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1124            1)      0 refs/heads/master
1125
1126           Inactive Branches
1127           -----------------
1128           refs/heads/master:
1129             status      : active loaded dirty
1130             tip commit  : 0000000000000000000000000000000000000000
1131             old tree    : 0000000000000000000000000000000000000000
1132             cur tree    : 0000000000000000000000000000000000000000
1133             commit clock: 0
1134             last pack   :
1135
1136           -------------------
1137           END OF CRASH REPORT
1138

TIPS AND TRICKS

1140       The following tips and tricks have been collected from various users of
1141       fast-import, and are offered here as suggestions.
1142
1143   Use One Mark Per Commit
1144       When doing a repository conversion, use a unique mark per commit (mark
1145       :<n>) and supply the --export-marks option on the command line.
1146       fast-import will dump a file which lists every mark and the Git object
1147       SHA-1 that corresponds to it. If the frontend can tie the marks back to
1148       the source repository, it is easy to verify the accuracy and
1149       completeness of the import by comparing each Git commit to the
1150       corresponding source revision.
1151
1152       Coming from a system such as Perforce or Subversion this should be
1153       quite simple, as the fast-import mark can also be the Perforce
1154       changeset number or the Subversion revision number.
1155
1156   Freely Skip Around Branches
1157       Don’t bother trying to optimize the frontend to stick to one branch at
1158       a time during an import. Although doing so might be slightly faster for
1159       fast-import, it tends to increase the complexity of the frontend code
1160       considerably.
1161
1162       The branch LRU builtin to fast-import tends to behave very well, and
1163       the cost of activating an inactive branch is so low that bouncing
1164       around between branches has virtually no impact on import performance.
1165
1166   Handling Renames
1167       When importing a renamed file or directory, simply delete the old
1168       name(s) and modify the new name(s) during the corresponding commit. Git
1169       performs rename detection after-the-fact, rather than explicitly during
1170       a commit.
1171
1172   Use Tag Fixup Branches
1173       Some other SCM systems let the user create a tag from multiple files
1174       which are not from the same commit/changeset. Or to create tags which
1175       are a subset of the files available in the repository.
1176
1177       Importing these tags as-is in Git is impossible without making at least
1178       one commit which “fixes up” the files to match the content of the tag.
1179       Use fast-import’s reset command to reset a dummy branch outside of your
1180       normal branch space to the base commit for the tag, then commit one or
1181       more file fixup commits, and finally tag the dummy branch.
1182
1183       For example since all normal branches are stored under refs/heads/ name
1184       the tag fixup branch TAG_FIXUP. This way it is impossible for the fixup
1185       branch used by the importer to have namespace conflicts with real
1186       branches imported from the source (the name TAG_FIXUP is not
1187       refs/heads/TAG_FIXUP).
1188
1189       When committing fixups, consider using merge to connect the commit(s)
1190       which are supplying file revisions to the fixup branch. Doing so will
1191       allow tools such as git blame to track through the real commit history
1192       and properly annotate the source files.
1193
1194       After fast-import terminates the frontend will need to do rm
1195       .git/TAG_FIXUP to remove the dummy branch.
1196
1197   Import Now, Repack Later
1198       As soon as fast-import completes the Git repository is completely valid
1199       and ready for use. Typically this takes only a very short time, even
1200       for considerably large projects (100,000+ commits).
1201
1202       However repacking the repository is necessary to improve data locality
1203       and access performance. It can also take hours on extremely large
1204       projects (especially if -f and a large --window parameter is used).
1205       Since repacking is safe to run alongside readers and writers, run the
1206       repack in the background and let it finish when it finishes. There is
1207       no reason to wait to explore your new Git project!
1208
1209       If you choose to wait for the repack, don’t try to run benchmarks or
1210       performance tests until repacking is completed. fast-import outputs
1211       suboptimal packfiles that are simply never seen in real use situations.
1212
1213   Repacking Historical Data
1214       If you are repacking very old imported data (e.g. older than the last
1215       year), consider expending some extra CPU time and supplying --window=50
1216       (or higher) when you run git repack. This will take longer, but will
1217       also produce a smaller packfile. You only need to expend the effort
1218       once, and everyone using your project will benefit from the smaller
1219       repository.
1220
1221   Include Some Progress Messages
1222       Every once in a while have your frontend emit a progress message to
1223       fast-import. The contents of the messages are entirely free-form, so
1224       one suggestion would be to output the current month and year each time
1225       the current commit date moves into the next month. Your users will feel
1226       better knowing how much of the data stream has been processed.
1227

PACKFILE OPTIMIZATION

1229       When packing a blob fast-import always attempts to deltify against the
1230       last blob written. Unless specifically arranged for by the frontend,
1231       this will probably not be a prior version of the same file, so the
1232       generated delta will not be the smallest possible. The resulting
1233       packfile will be compressed, but will not be optimal.
1234
1235       Frontends which have efficient access to all revisions of a single file
1236       (for example reading an RCS/CVS ,v file) can choose to supply all
1237       revisions of that file as a sequence of consecutive blob commands. This
1238       allows fast-import to deltify the different file revisions against each
1239       other, saving space in the final packfile. Marks can be used to later
1240       identify individual file revisions during a sequence of commit
1241       commands.
1242
1243       The packfile(s) created by fast-import do not encourage good disk
1244       access patterns. This is caused by fast-import writing the data in the
1245       order it is received on standard input, while Git typically organizes
1246       data within packfiles to make the most recent (current tip) data appear
1247       before historical data. Git also clusters commits together, speeding up
1248       revision traversal through better cache locality.
1249
1250       For this reason it is strongly recommended that users repack the
1251       repository with git repack -a -d after fast-import completes, allowing
1252       Git to reorganize the packfiles for faster data access. If blob deltas
1253       are suboptimal (see above) then also adding the -f option to force
1254       recomputation of all deltas can significantly reduce the final packfile
1255       size (30-50% smaller can be quite typical).
1256

MEMORY UTILIZATION

1258       There are a number of factors which affect how much memory fast-import
1259       requires to perform an import. Like critical sections of core Git,
1260       fast-import uses its own memory allocators to amortize any overheads
1261       associated with malloc. In practice fast-import tends to amortize any
1262       malloc overheads to 0, due to its use of large block allocations.
1263
1264   per object
1265       fast-import maintains an in-memory structure for every object written
1266       in this execution. On a 32 bit system the structure is 32 bytes, on a
1267       64 bit system the structure is 40 bytes (due to the larger pointer
1268       sizes). Objects in the table are not deallocated until fast-import
1269       terminates. Importing 2 million objects on a 32 bit system will require
1270       approximately 64 MiB of memory.
1271
1272       The object table is actually a hashtable keyed on the object name (the
1273       unique SHA-1). This storage configuration allows fast-import to reuse
1274       an existing or already written object and avoid writing duplicates to
1275       the output packfile. Duplicate blobs are surprisingly common in an
1276       import, typically due to branch merges in the source.
1277
1278   per mark
1279       Marks are stored in a sparse array, using 1 pointer (4 bytes or 8
1280       bytes, depending on pointer size) per mark. Although the array is
1281       sparse, frontends are still strongly encouraged to use marks between 1
1282       and n, where n is the total number of marks required for this import.
1283
1284   per branch
1285       Branches are classified as active and inactive. The memory usage of the
1286       two classes is significantly different.
1287
1288       Inactive branches are stored in a structure which uses 96 or 120 bytes
1289       (32 bit or 64 bit systems, respectively), plus the length of the branch
1290       name (typically under 200 bytes), per branch. fast-import will easily
1291       handle as many as 10,000 inactive branches in under 2 MiB of memory.
1292
1293       Active branches have the same overhead as inactive branches, but also
1294       contain copies of every tree that has been recently modified on that
1295       branch. If subtree include has not been modified since the branch
1296       became active, its contents will not be loaded into memory, but if
1297       subtree src has been modified by a commit since the branch became
1298       active, then its contents will be loaded in memory.
1299
1300       As active branches store metadata about the files contained on that
1301       branch, their in-memory storage size can grow to a considerable size
1302       (see below).
1303
1304       fast-import automatically moves active branches to inactive status
1305       based on a simple least-recently-used algorithm. The LRU chain is
1306       updated on each commit command. The maximum number of active branches
1307       can be increased or decreased on the command line with
1308       --active-branches=.
1309
1310   per active tree
1311       Trees (aka directories) use just 12 bytes of memory on top of the
1312       memory required for their entries (see “per active file” below). The
1313       cost of a tree is virtually 0, as its overhead amortizes out over the
1314       individual file entries.
1315
1316   per active file entry
1317       Files (and pointers to subtrees) within active trees require 52 or 64
1318       bytes (32/64 bit platforms) per entry. To conserve space, file and tree
1319       names are pooled in a common string table, allowing the filename
1320       “Makefile” to use just 16 bytes (after including the string header
1321       overhead) no matter how many times it occurs within the project.
1322
1323       The active branch LRU, when coupled with the filename string pool and
1324       lazy loading of subtrees, allows fast-import to efficiently import
1325       projects with 2,000+ branches and 45,114+ files in a very limited
1326       memory footprint (less than 2.7 MiB per active branch).
1327

SIGNALS

1329       Sending SIGUSR1 to the git fast-import process ends the current
1330       packfile early, simulating a checkpoint command. The impatient operator
1331       can use this facility to peek at the objects and refs from an import in
1332       progress, at the cost of some added running time and worse compression.
1333

SEE ALSO

1335       git-fast-export(1)
1336

GIT

1338       Part of the git(1) suite
1339
1340
1341
1342Git 2.21.0                        02/24/2019                GIT-FAST-IMPORT(1)
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