-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathpax.1
1325 lines (1325 loc) · 32.1 KB
/
pax.1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
.\" $NetBSD: pax.1,v 1.5 2005/12/01 03:00:01 minskim Exp $
.\"
.\" Copyright (c) 1992 Keith Muller.
.\" Copyright (c) 1992, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Keith Muller of the University of California, San Diego.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" @(#)pax.1 8.4 (Berkeley) 4/18/94
.\"
.Dd June 18, 2004
.Dt PAX 1
.Os
.Sh NAME
.Nm pax
.Nd read and write file archives and copy directory hierarchies
.Sh SYNOPSIS
.Nm
.Op Fl 0cdjnvzO
.Bk -words
.Op Fl E Ar limit
.Ek
.Bk -words
.Op Fl f Ar archive
.Ek
.Bk -words
.Op Fl N Ar dbdir
.Ek
.Bk -words
.Op Fl s Ar replstr
.Ar ...\&
.Ek
.Bk -words
.Op Fl U Ar user
.Ar ...\&
.Ek
.Bk -words
.Op Fl G Ar group
.Ar ...\&
.Ek
.Bk -words
.Oo
.Fl T
.Op Ar from_date
.Sm off
.Oo , Ar to_date Oc
.Sm on
.Oc
.Ar ...\&
.Ek
.Op Ar pattern ...\&
.Nm
.Fl r
.Op Fl cdijknuvzADOYZ
.Bk -words
.Op Fl E Ar limit
.Ek
.Bk -words
.Op Fl f Ar archive
.Ek
.Bk -words
.Op Fl N Ar dbdir
.Ek
.Bk -words
.Op Fl o Ar options
.Ar ...\&
.Ek
.Bk -words
.Op Fl p Ar string
.Ar ...\&
.Ek
.Bk -words
.Op Fl s Ar replstr
.Ar ...\&
.Ek
.Bk -words
.Op Fl U Ar user
.Ar ...\&
.Ek
.Bk -words
.Op Fl G Ar group
.Ar ...\&
.Ek
.Bk -words
.Oo
.Fl T
.Op Ar from_date
.Sm off
.Oo , Ar to_date Oc
.Sm on
.Oc
.Ar ...\&
.Ek
.Op Ar pattern ...\&
.Nm
.Fl w
.Op Fl dijtuvzAHLMOPX
.Bk -words
.Op Fl b Ar blocksize
.Ek
.Oo
.Op Fl a
.Op Fl f Ar archive
.Oc
.Bk -words
.Op Fl x Ar format
.Ek
.Bk -words
.Op Fl B Ar bytes
.Ek
.Bk -words
.Op Fl N Ar dbdir
.Ek
.Bk -words
.Op Fl o Ar options
.Ar ...\&
.Ek
.Bk -words
.Op Fl s Ar replstr
.Ar ...\&
.Ek
.Bk -words
.Op Fl U Ar user
.Ar ...\&
.Ek
.Bk -words
.Op Fl G Ar group
.Ar ...\&
.Ek
.Bk -words
.Oo
.Fl T
.Op Ar from_date
.Sm off
.Oo , Ar to_date Oc
.Oo /[ Cm c ] [ Cm m ] Oc
.Sm on
.Oc
.Ar ...\&
.Ek
.Op Ar file ...\&
.Nm
.Fl r
.Fl w
.Op Fl dijklntuvzADHLMOPXYZ
.Bk -words
.Op Fl N Ar dbdir
.Ek
.Bk -words
.Op Fl p Ar string
.Ar ...\&
.Ek
.Bk -words
.Op Fl s Ar replstr
.Ar ...\&
.Ek
.Bk -words
.Op Fl U Ar user
.Ar ...\&
.Ek
.Bk -words
.Op Fl G Ar group
.Ar ...\&
.Ek
.Bk -words
.Oo
.Fl T
.Op Ar from_date
.Sm off
.Oo , Ar to_date Oc
.Oo /[ Cm c ] [ Cm m ] Oc
.Sm on
.Oc
.Ar ...\&
.Ek
.Bk -words
.Op Ar file ...\&
.Ek
.Ar directory
.Sh DESCRIPTION
.Nm
will read, write, and list the members of an archive file,
and will copy directory hierarchies.
If the archive file is of the form:
.Ar [[user@]host:]file
then the archive will be processed using
.Xr rmt 8 .
.Pp
.Nm
operation is independent of the specific archive format,
and supports a wide variety of different archive formats.
A list of supported archive formats can be found under the description of the
.Fl x
option.
.Pp
The presence of the
.Fl r
and the
.Fl w
options specifies which of the following functional modes
.Nm
will operate under:
.Em list , read , write ,
and
.Em copy .
.Bl -tag -width 6n
.It Aq none
.Em List .
.Nm
will write to
.Dv standard output
a table of contents of the members of the archive file read from
.Dv standard input ,
whose pathnames match the specified
.Ar patterns .
The table of contents contains one filename per line
and is written using single line buffering.
.It Fl r
.Em Read .
.Nm
extracts the members of the archive file read from the
.Dv standard input ,
with pathnames matching the specified
.Ar patterns .
The archive format and blocking is automatically determined on input.
When an extracted file is a directory, the entire file hierarchy
rooted at that directory is extracted.
All extracted files are created relative to the current file hierarchy.
The setting of ownership, access and modification times, and file mode of
the extracted files are discussed in more detail under the
.Fl p
option.
.It Fl w
.Em Write .
.Nm
writes an archive containing the
.Ar file
operands to
.Dv standard output
using the specified archive format.
When no
.Ar file
operands are specified, a list of files to copy with one per line is read from
.Dv standard input .
When a
.Ar file
operand is also a directory, the entire file hierarchy rooted
at that directory will be included.
.It Fl r Fl w
.Em Copy .
.Nm
copies the
.Ar file
operands to the destination
.Ar directory .
When no
.Ar file
operands are specified, a list of files to copy with one per line is read from
the
.Dv standard input .
When a
.Ar file
operand is also a directory the entire file
hierarchy rooted at that directory will be included.
The effect of the
.Em copy
is as if the copied files were written to an archive file and then
subsequently extracted, except that there may be hard links between
the original and the copied files (see the
.Fl l
option below).
.Pp
.Em Warning :
The destination
.Ar directory
must not be one of the
.Ar file
operands or a member of a file hierarchy rooted at one of the
.Ar file
operands.
The result of a
.Em copy
under these conditions is unpredictable.
.El
.Pp
While processing a damaged archive during a
.Em read
or
.Em list
operation,
.Nm
will attempt to recover from media defects and will search through the archive
to locate and process the largest number of archive members possible (see the
.Fl E
option for more details on error handling).
.Sh OPERANDS
The
.Ar directory
operand specifies a destination directory pathname.
If the
.Ar directory
operand does not exist, or it is not writable by the user,
or it is not of type directory,
.Nm
will exit with a non-zero exit status.
.Pp
The
.Ar pattern
operand is used to select one or more pathnames of archive members.
Archive members are selected using the pattern matching notation described
by
.Xr fnmatch 3 .
When the
.Ar pattern
operand is not supplied, all members of the archive will be selected.
When a
.Ar pattern
matches a directory, the entire file hierarchy rooted at that directory will
be selected.
When a
.Ar pattern
operand does not select at least one archive member,
.Nm
will write these
.Ar pattern
operands in a diagnostic message to
.Dv standard error
and then exit with a non-zero exit status.
.Pp
The
.Ar file
operand specifies the pathname of a file to be copied or archived.
When a
.Ar file
operand does not select at least one archive member,
.Nm
will write these
.Ar file
operand pathnames in a diagnostic message to
.Dv standard error
and then exit with a non-zero exit status.
.Sh OPTIONS
The following options are supported:
.Bl -tag -width 4n
.It Fl r
Read an archive file from
.Dv standard input
and extract the specified
.Ar files .
If any intermediate directories are needed in order to extract an archive
member, these directories will be created as if
.Xr mkdir 2
was called with the bitwise inclusive
.Dv OR
of
.Dv S_IRWXU , S_IRWXG ,
and
.Dv S_IRWXO
as the mode argument.
When the selected archive format supports the specification of linked
files and these files cannot be linked while the archive is being extracted,
.Nm
will write a diagnostic message to
.Dv standard error
and exit with a non-zero exit status at the completion of operation.
.It Fl w
Write files to the
.Dv standard output
in the specified archive format.
When no
.Ar file
operands are specified,
.Dv standard input
is read for a list of pathnames with one per line without any leading or
trailing
.Aq blanks .
.It Fl a
Append
.Ar files
to the end of an archive that was previously written.
If an archive format is not specified with a
.Fl x
option, the format currently being used in the archive will be selected.
Any attempt to append to an archive in a format different from the
format already used in the archive will cause
.Nm
to exit immediately
with a non-zero exit status.
The blocking size used in the archive volume where writing starts
will continue to be used for the remainder of that archive volume.
.Pp
.Em Warning :
Many storage devices are not able to support the operations necessary
to perform an append operation.
Any attempt to append to an archive stored on such a device may damage the
archive or have other unpredictable results.
Tape drives in particular are more likely to not support an append operation.
An archive stored in a regular file system file or on a disk device will
usually support an append operation.
.It Fl b Ar blocksize
When
.Em writing
an archive,
block the output at a positive decimal integer number of
bytes per write to the archive file.
The
.Ar blocksize
must be a multiple of 512 bytes with a maximum of 32256 bytes.
A
.Ar blocksize
can end with
.Li k
or
.Li b
to specify multiplication by 1024 (1K) or 512, respectively.
A pair of
.Ar blocksizes
can be separated by
.Li x
to indicate a product.
A specific archive device may impose additional restrictions on the size
of blocking it will support.
When blocking is not specified, the default
.Ar blocksize
is dependent on the specific archive format being used (see the
.Fl x
option).
.It Fl c
Match all file or archive members
.Em except
those specified by the
.Ar pattern
and
.Ar file
operands.
.It Fl d
Cause files of type directory being copied or archived, or archive members of
type directory being extracted, to match only the directory file or archive
member and not the file hierarchy rooted at the directory.
.It Fl f Ar archive
Specify
.Ar archive
as the pathname of the input or output archive, overriding the default
.Dv standard input
(for
.Em list
and
.Em read )
or
.Dv standard output
(for
.Em write ) .
A single archive may span multiple files and different archive devices.
When required,
.Nm
will prompt for the pathname of the file or device of the next volume in the
archive.
.It Fl i
Interactively rename files or archive members.
For each archive member matching a
.Ar pattern
operand or each file matching a
.Ar file
operand,
.Nm
will prompt to
.Pa /dev/tty
giving the name of the file, its file mode and its modification time.
.Nm
will then read a line from
.Pa /dev/tty .
If this line is blank, the file or archive member is skipped.
If this line consists of a single period, the
file or archive member is processed with no modification to its name.
Otherwise, its name is replaced with the contents of the line.
.Nm
will immediately exit with a non-zero exit status if
.Aq Dv EOF
is encountered when reading a response or if
.Pa /dev/tty
cannot be opened for reading and writing.
.It Fl j
Use
.Xr bzip2 1
for compression when reading or writing archive files.
.It Fl k
Do not overwrite existing files.
.It Fl l
Link files.
(The letter ell).
In the
.Em copy
mode
.Fl ( r
.Fl w ) ,
hard links are made between the source and destination file hierarchies
whenever possible.
.It Fl n
Select the first archive member that matches each
.Ar pattern
operand.
No more than one archive member is matched for each
.Ar pattern .
When members of type directory are matched, the file hierarchy rooted at that
directory is also matched (unless
.Fl d
is also specified).
.It Fl o Ar options
Information to modify the algorithm for extracting or writing archive files
which is specific to the archive format specified by
.Fl x .
In general,
.Ar options
take the form:
.Cm name=value
.It Fl p Ar string
Specify one or more file characteristic options (privileges).
The
.Ar string
option-argument is a string specifying file characteristics to be retained or
discarded on extraction.
The string consists of the specification characters
.Cm a , e , f ,
.Cm m , o ,
and
.Cm p .
Multiple characteristics can be concatenated within the same string
and multiple
.Fl p
options can be specified.
The meaning of the specification characters are as follows:
.Bl -tag -width 2n
.It Cm a
Do not preserve file access times.
By default, file access times are preserved whenever possible.
.It Cm e
.Sq Preserve everything ,
the user ID, group ID, file mode bits,
file access time, and file modification time.
This is intended to be used by
.Em root ,
someone with all the appropriate privileges, in order to preserve all
aspects of the files as they are recorded in the archive.
The
.Cm e
flag is the sum of the
.Cm o
and
.Cm p
flags.
.\" .It Cm f
.\" Do not preserve file flags.
.\" By default, file flags are preserved whenever possible.
.It Cm m
Do not preserve file modification times.
By default, file modification times are preserved whenever possible.
.It Cm o
Preserve the user ID and group ID.
.It Cm p
.Sq Preserve
the file mode bits.
This is intended to be used by a
.Em user
with regular privileges who wants to preserve all aspects of the file other
than the ownership.
The file times are preserved by default, but two other flags are offered to
disable this and use the time of extraction instead.
.El
.Pp
In the preceding list,
.Sq preserve
indicates that an attribute stored in the archive is given to the
extracted file, subject to the permissions of the invoking
process.
Otherwise the attribute of the extracted file is determined as
part of the normal file creation action.
If neither the
.Cm e
nor the
.Cm o
specification character is specified, or the user ID and group ID are not
preserved for any reason,
.Nm
will not set the
.Dv S_ISUID
.Em ( setuid )
and
.Dv S_ISGID
.Em ( setgid )
bits of the file mode.
If the preservation of any of these items fails for any reason,
.Nm
will write a diagnostic message to
.Dv standard error .
Failure to preserve these items will affect the final exit status,
but will not cause the extracted file to be deleted.
If the file characteristic letters in any of the string option-arguments are
duplicated or conflict with each other, the one(s) given last will take
precedence.
For example, if
.Dl Fl p Ar eme
is specified, file modification times are still preserved.
.It Fl s Ar replstr
Modify the file or archive member names specified by the
.Ar pattern
or
.Ar file
operands according to the substitution expression
.Ar replstr ,
using the syntax of the
.Xr ed 1
utility regular expressions.
The format of these regular expressions are:
.Dl /old/new/[gp]
As in
.Xr ed 1 ,
.Cm old
is a basic regular expression and
.Cm new
can contain an ampersand (\*[Am]), \\n (where n is a digit) back-references,
or subexpression matching.
The
.Cm old
string may also contain
.Aq Dv newline
characters.
Any non-null character can be used as a delimiter (/ is shown here).
Multiple
.Fl s
expressions can be specified.
The expressions are applied in the order they are specified on the
command line, terminating with the first successful substitution.
The optional trailing
.Cm g
continues to apply the substitution expression to the pathname substring
which starts with the first character following the end of the last successful
substitution.
The first unsuccessful substitution stops the operation of the
.Cm g
option.
The optional trailing
.Cm p
will cause the final result of a successful substitution to be written to
.Dv standard error
in the following format:
.Dl Ao "original pathname" Ac \*[Gt]\*[Gt] Ao "new pathname" Ac
File or archive member names that substitute to the empty string
are not selected and will be skipped.
.It Fl t
Reset the access times of any file or directory read or accessed by
.Nm
to be the same as they were before being read or accessed by
.Nm ,
if the user has the appropriate permissions required by
.Xr utime 3 .
.It Fl u
Ignore files that are older (having a less recent file modification time)
than a pre-existing file or archive member with the same name.
During
.Em read ,
an archive member with the same name as a file in the file system will be
extracted if the archive member is newer than the file.
During
.Em write ,
a file system member with the same name as an archive member will be
written to the archive if it is newer than the archive member.
During
.Em copy ,
the file in the destination hierarchy is replaced by the file in the source
hierarchy or by a link to the file in the source hierarchy if the file in
the source hierarchy is newer.
.It Fl v
During a
.Em list
operation, produce a verbose table of contents using the format of the
.Xr ls 1
utility with the
.Fl l
option.
For pathnames representing a hard link to a previous member of the archive,
the output has the format:
.Dl Ao "ls -l listing" Ac == Ao "link name" Ac
Where
.Aq "ls -l listing"
is the output format specified by the
.Xr ls 1
utility when used with the
.Fl l
option.
Otherwise for all the other operational modes
.Em ( read , write ,
and
.Em copy ) ,
pathnames are written and flushed to
.Dv standard error
without a trailing
.Aq Dv newline
as soon as processing begins on that file or
archive member.
The trailing
.Aq Dv newline ,
is not buffered, and is written only after the file has been read or written.
.It Fl x Ar format
Specify the output archive format, with the default format being
.Ar ustar .
.Nm
currently supports the following formats:
.Bl -tag -width "sv4cpio"
.It Ar cpio
The extended cpio interchange format specified in the
.St -p1003.2
standard.
The default blocksize for this format is 5120 bytes.
Inode and device information about a file (used for detecting file hard links
by this format) which may be truncated by this format is detected by
.Nm
and is repaired.
.It Ar bcpio
The old binary cpio format.
The default blocksize for this format is 5120 bytes.
This format is not very portable and should not be used when other formats
are available.
Inode and device information about a file (used for detecting file hard links
by this format) which may be truncated by this format is detected by
.Nm
and is repaired.
.It Ar sv4cpio
The
.At V.4
cpio.
The default blocksize for this format is 5120 bytes.
Inode and device information about a file (used for detecting file hard links
by this format) which may be truncated by this format is detected by
.Nm
and is repaired.
.It Ar sv4crc
The
.At V.4
cpio with file crc checksums.
The default blocksize for this format is 5120 bytes.
Inode and device information about a file (used for detecting file hard links
by this format) which may be truncated by this format is detected by
.Nm
and is repaired.
.It Ar tar
The old
.Bx
tar format as found in
.Bx 4.3 .
The default blocksize for this format is 10240 bytes.
Pathnames stored by this format must be 100 characters or less in length.
Only
.Em regular
files,
.Em hard links , soft links ,
and
.Em directories
will be archived (other file types are not supported).
For backward compatibility with even older tar formats, a
.Fl o
option can be used when writing an archive to omit the storage of directories.
This option takes the form:
.Dl Fl o Cm write_opt=nodir
.It Ar ustar
The extended tar interchange format specified in the
.St -p1003.2
standard.
The default blocksize for this format is 10240 bytes.
Pathnames stored by this format must be 250 characters or less in length.
.El
.Pp
.Nm
will detect and report any file that it is unable to store or extract
as the result of any specific archive format restrictions.
The individual archive formats may impose additional restrictions on use.
Typical archive format restrictions include (but are not limited to):
file pathname length, file size, link pathname length and the type of the file.
.It Fl z
Use
.Xr gzip 1
compression, when reading or writing archive files.
.It Fl A
Do not strip leading `/'s from file names.
.It Fl B Ar bytes
Limit the number of bytes written to a single archive volume to
.Ar bytes .
The
.Ar bytes
limit can end with
.Li m ,
.Li k ,
or
.Li b
to specify multiplication by 1048576 (1M), 1024 (1K) or 512, respectively.
A pair of
.Ar bytes
limits can be separated by
.Li x
to indicate a product.
.Pp
.Em Warning :
Only use this option when writing an archive to a device which supports
an end of file read condition based on last (or largest) write offset
(such as a regular file or a tape drive).
The use of this option with a floppy or hard disk is not recommended.
.It Fl D
This option is the same as the
.Fl u
option, except that the file inode change time is checked instead of the
file modification time.
The file inode change time can be used to select files whose inode information
(e.g. uid, gid, etc.) is newer than a copy of the file in the destination
.Ar directory .
.It Fl E Ar limit
Limit the number of consecutive read faults while trying to read a flawed
archives to
.Ar limit .
With a positive
.Ar limit ,
.Nm
will attempt to recover from an archive read error and will
continue processing starting with the next file stored in the archive.
A
.Ar limit
of 0 will cause
.Nm
to stop operation after the first read error is detected on an archive volume.
A
.Ar limit
of
.Li NONE
will cause
.Nm
to attempt to recover from read errors forever.
The default
.Ar limit
is a small positive number of retries.
.Pp
.Em Warning :
Using this option with
.Li NONE
should be used with extreme caution as
.Nm
may get stuck in an infinite loop on a very badly flawed archive.
.It Fl G Ar group
Select a file based on its
.Ar group
name, or when starting with a
.Cm # ,
a numeric gid.
A '\\' can be used to escape the
.Cm # .
Multiple
.Fl G
options may be supplied and checking stops with the first match.
.It Fl H
Follow only command line symbolic links while performing a physical file
system traversal.
.It Fl L
Follow all symbolic links to perform a logical file system traversal.
.It Fl M
During a
.Em write
or
.Em copy
operation, treat the list of files on
.Dv standard input
as an
.Xr mtree 8
.Sq specfile
specification, and write or copy only those items in the specfile.
.Pp
If the file exists in the underlying file system, its permissions and
modification time will be used unless specifically overridden by the specfile.
An error will be raised if the type of entry in the specfile conflicts
with that of an existing file.
A directory entry that is marked
.Sq Sy optional
will not be copied (even though its contents will be).
.Pp
Otherwise, the entry will be
.Sq faked-up ,
and it is necessary to specify at least the following parameters
in the specfile:
.Sy type ,
.Sy mode ,
.Sy gname
or
.Sy gid ,
and
.Sy uname
or
.Sy uid ,
.Sy device
(in the case of block or character devices), and
.Sy link
(in the case of symbolic links).
If
.Sy time
isn't provided, the current time will be used.
A
.Sq faked-up
entry that is marked
.Sq Sy optional
will not be copied.
.It Fl N Ar dbdir
Except for lookups for the
.Fl G
and
.Fl U
options,
use the user database text file
.Pa master.passwd
and group database text file
.Pa group
from
.Ar dbdir ,
rather than using the results from the system's
.Xr getpwnam 3
and
.Xr getgrnam 3
(and related) library calls.
.It Fl O
Force the archive to be one volume.
If a volume ends prematurely,
.Nm
will not prompt for a new volume.
This option can be useful for
automated tasks where error recovery cannot be performed by a human.
.It Fl P
Do not follow symbolic links, perform a physical file system traversal.
This is the default mode.
.It Fl T Ar [from_date][,to_date][/[c][m]]
Allow files to be selected based on a file modification or inode change
time falling within a specified time range of
.Ar from_date
to
.Ar to_date
(the dates are inclusive).
If only a
.Ar from_date
is supplied, all files with a modification or inode change time
equal to or younger are selected.
If only a
.Ar to_date
is supplied, all files with a modification or inode change time
equal to or older will be selected.
When the
.Ar from_date
is equal to the
.Ar to_date ,
only files with a modification or inode change time of exactly that
time will be selected.
.Pp
When
.Nm
is in the
.Em write
or
.Em copy
mode, the optional trailing field
.Ar [c][m]
can be used to determine which file time (inode change, file modification or
both) are used in the comparison.
If neither is specified, the default is to use file modification time only.
The
.Ar m
specifies the comparison of file modification time (the time when
the file was last written).
The
.Ar c
specifies the comparison of inode change time (the time when the file
inode was last changed; e.g. a change of owner, group, mode, etc).
When
.Ar c