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[lindexi]

Tar 文档

NAME
tar - create tape archives, and add or extract files

SYNOPSIS
/usr/sbin/tar c [ bBefFhilvwX [ 0-7 ]] [ device ] [ block ]
[ exclude-filename ... ] [ -I include-filename ]
filename ... [ -C directory filename ]

 /usr/sbin/tar r [ bBefFhilvw [ 0-7 ]] [ device ] [ block ]
      [ -I include-filename ] filename ...
      [ -C directory filename ]

 /usr/sbin/tar t [ BefFhilvX [ 0-7 ]] [ device ]
      [ exclude-filename ... ] [ -I include-filename ]
      [ filename ... ]

 /usr/sbin/tar u [ bBefFhilvw [ 0-7 ]] [ device ] [ block ]
      filename ...

 /usr/sbin/tar x [ BefFhilmopvwX [ 0-7 ]] [ device ]
      [ exclude-filename ... ] [ filename ... ]

DESCRIPTION
tar archives and extracts files to and from a single file
called a tarfile . A tarfile is usually a magnetic tape, but
it can be any file. tar's actions are controlled by the key
argument. The key is a string of characters containing
exactly one function letter (c, r, t , u, or x) and one or
more function modifiers, depending on the function letter
used. Other arguments to the command are filenames (or
directory names) specifying which files are to be archived
or extracted. In all cases, appearance of a directory name
refers to the files and (recursively) subdirectories of that
directory.

Function Letters
The function portion of the key is specified by one of the
following letters:

 c    Create. Writing begins at the beginning of the tarfile,
      instead of at the end.  This key implies the r key.

 r    Replace.  The named filenames are written on the end of
      the  tape.   The c and u functions imply this function.
      See NOTES for more information.

 t    Table of Contents. The names of the specified files are
      listed  each  time  they  occur  on the tarfile.  If no
      filenames arguments are given, all  the  names  on  the
      tarfile  are  listed.   With  the  v function modifier,
      additional  information  for  the  specified  files  is
      displayed.   The  listing  is  similar  to  the  format
      produced by the ls -l command.

 u    Update.  The named filenames are added to  the  tarfile
      if  they  are  not already there, or have been modified
      since last written on that tarfile.  This  key  implies
      the r key. See NOTES for more information.

 x    Extract, or restore.  The named filenames are extracted
      from  the tarfile and written to the current directory.
      If a named file matches a directory whose contents  had
      been  written  onto  the  tarfile,  this  directory  is
      (recursively) extracted.  Use the file  or  directory's
      relative  path when appropriate, or tar will not find a
      match.  The owner,  modification  time,  and  mode  are
      restored  (if  possible);  otherwise, to restore owner,
      you must be the superuser.  If no filenames argument is
      given,  the entire content of the tarfile is extracted.
      Note:  If several files with the same name are  on  the
      tarfile, the last one overwrites all earlier ones.  See
      NOTES for more information.

Function Modifiers
The characters below may be used in addition to the letter
that selects the desired function. Use them in the order
shown in the SYNOPSIS.

 b       Blocking Factor.  This causes tar to use  the  block
         argument  as  the  blocking factor for tape records.
         The default is 1, the maximum is 20.  This  function
         should  not  be  supplied  when operating on regular
         archives or block special devices.  It is  mandatory
         however,  when reading archives on raw magnetic tape
         archives (see f below).  The block  size  is  deter-
         mined  automatically  when  reading tapes created on
         block special devices (key letters x and  t).   This
         determination  of  the blocking factor may be fooled
         when reading from a pipe or a socket (see the B  key
         letter  below).   The  maximum  blocking  factor  is
         determined only by the amount of memory available to
         tar  when it is run.  Larger blocking factors result
         in better throughput, longer  blocks  on  nine-track
         tapes, and better media utilization.

 B       Block.  Force tar  to  perform  multiple  reads  (if
         necessary)  so  as  to  read exactly enough bytes to
         fill a block.  This option exists so  that  tar  can
         work  across  the  Ethernet, since pipes and sockets
         return partial blocks even when more data is coming.
         When  reading  from standard input, '-', this option
         is automatically selected to make sure that tar  can
         recover from short reads.

 e       Error.  If any unexpected errors occur tar will exit
         immediately with a positive exit status.

 f       File.  This causes tar to use the device argument as
         the   name   of   the   tarfile.   If  f  is  given,
         /etc/default/tar is not searched.  If f is  omitted,
         tar  will  use  the  device  indicated  by  the TAPE
         environment variable, if set; otherwise, it will use
         the  default values defined in /etc/default/tar.  If
         the name of the tarfile is '-', tar  writes  to  the
         standard  output  or  reads from the standard input,
         whichever is appropriate.  Thus, tar can be used  as
         the  head  or  tail  of a pipeline.  tar can also be
         used to move hierarchies with the command:
            example% cd fromdir; tar cf - . | (cd todir;  tar
         xfBp -)

 F       With one F argument, tar  will  exclude  all  direc-
         tories  named SCCS from the tarfile.  With two argu-
         ments, FF , tar will exclude all  directories  named
         SCCS,  all  files  with  .o as their suffix, and all
         files named errs, core, and a.out.

 h       Follow symbolic links as if they were  normal  files
         or  directories.  Normally, tar does not follow sym-
         bolic links.

 i       Ignore.  With this option tar will ignore  directory
         checksum errors.

 l       Link.  This tells  tar  to  complain  if  it  cannot
         resolve   all  of  the  links  to  the  files  being
         archived.  If l is not specified, no error  messages
         are printed.

 m       Modify.  This tells tar to not extract the modifica-
         tion  times from the tarfile.  The modification time
         of the file will be the time  of  extraction.   This
         option is only valid with the x key.

 o       Ownership.  This causes extracted files to  take  on
         the  user  and  group identifier of the user running
         the program, rather than those on tape.   This  hap-
         pens  by  default for users other than root.  If the
         'o' option is not set and  the  user  is  root,  the
         extracted  files  will  take  on  the group and user
         identifiers of the files on tape (see  chown(1)  for
         more  information).   The  'o'  option is only valid
         with the x key.



 p       Restore the named files  to  their  original  modes,
         ignoring  the  present  umask(2).  SETUID and sticky
         information are  also  extracted  if  your  are  the
         super-user.   This  option is only useful with the x
         key letter.

 v       Verbose.  Normally,  tar  does  its  work  silently.
         This option causes tar to type the name of each file
         it treats, preceded by the  function  letter.   With
         the  t  function, v gives more information about the
         tape entries than just the name.

 w       What.  This option causes tar to print the action to
         be taken, followed by the name of the file, and then
         wait for the user's confirmation.  If a word  begin-
         ning  with y is given, the action is performed.  Any
         other input means no.  This is not valid with the  t
         key.

 X       Exclude.  Use the  exclude-filename  argument  as  a
         file  containing  a  list  of named files (or direc-
         tories) to be excluded from the tarfile  when  using
         the  key  letters  c, x, or t.  Multiple X arguments
         may be used, with one exclude-filename per argument.
         See NOTES for more information.

 [0-7]   Select an alternative drive on  which  the  tape  is
         mounted.   The  default  entries  are  specified  in
         /etc/default/tar.

 If a file name is preceded by   - I  then  the  filename  is
 opened.   A  list  filenames, one per line, is treated as if
 each appeared separately on the command line.  Be careful of
 trailing white space in both include and exclude file lists.

 In the case where excluded files (see X option) also  exist,
 excluded files take precedence over all included files.  So,
 if a file is specified in both the include and exclude files
 (or on the command line), it will be excluded.

 If a file name is preceded by - C  in  a  c  (create)  or  r
 (replace)  operation,  tar will perform a chdir (see csh(1))
 to that file name.  This  allows  multiple  directories  not
 related  by a close common parent to be archived using short
 relative path names.

 Note: the -C option only applies to one following  directory
 name and one following file name.

 If no digit or 'f' is given, the entry  in  /etc/default/tar
 with digit "0" will be the default.

EXAMPLES
To archive files from /usr/include and from /etc, onto
default tape drive 0 one might use:

      example% tar c -C /usr  include -C /etc .

 If you get a table of contents from the  resulting  tarfile,
 you might see something like:
      include/
      include/a.out.h
      and all the other files in /usr/include ...
      /chown
      and all the other files in /etc
 To extract all files under include:
      example% tar xv include
      x include/, 0 bytes, 0 tape blocks
      and all files under include...

 Here is a simple example using tar to create an  archive  of
 your home directory on a tape mounted on drive /dev/rmt/0:
      example% cd
      example% tar cvf /dev/rmt/0 .
      messages from tar

 The c option means create the archive; the  v  option  makes
 tar  tell  you  what  it is doing as it works;  the f option
 means that you are specifically naming the file  onto  which
 the archive should be placed (/dev/rmt/0 in this example).

 Now you can read the table of contents from the archive like
 this:
      example% tar tvf /dev/rmt/0
      rw-r--r-- 1677/40 2123  Nov  7 18:15 1985     ./test.c
      ...
      example%

 The columns have the following meanings:

      o column 1 is the access permissions to ./test.c
      o column 2 is the user-id/group-id of ./test.c
      o column 3 is the size of ./test.c in bytes
      o column 4 is the modification date of ./test.c
      o column 5 is the name of ./test.c

 You can extract files from the archive like this:
      example% tar xvf /dev/rmt/0
      messages from tar
      example%

 If there are multiple archive  files  on  a  tape,  each  is
 separated from the following one by an EOF marker.  tar does
 not read the EOF mark on the tape after it finishes  reading
 an  archive  file  because tar looks for a special header to
 decide when it has reached the end of the archive.   Now  if
 you  try  to  use tar to read the next archive file from the
 tape, tar does not know enough to skip over the EOF mark and
 tries  to  read  the  EOF  mark  as an archive instead.  The
 result of this is an error message from tar to the effect:

      tar: blocksize=0

 This means that to read another archive from the  tape,  you
 must  skip  over  the EOF marker before starting another tar
 command.  You can accomplish this using the  mt(1)  command,
 as  shown in the example below.  Assume that you are reading
 from /dev/rmt/0n.
      example% tar xvfp /dev/rmt/0n   read first archive from tape
      messages from tar
      example% mt fsf 1               skip over the end-of-file marker
      example% tar xvfp /dev/rmt/0n   read second archive from tape
      messages from tar
      example%

 Finally, here is an example  using  tar  to  transfer  files
 across  the  Ethernet.   First, here is how to archive files
 from the local machine (example) to a tape on a remote  sys-
 tem (host):
      example% tar cvfb  -  20 filenames |
            rsh host dd of=/dev/rmt/0  obs=20b
      messages from tar
      example%

 In the example above, we are creating a tarfile with  the  c
 key  letter,  asking  for verbose output from tar with the v
 option, specifying the name of the output tarfile using  the
 f  option (the standard output is where the tarfile appears,
 as indicated by the `-' sign), and specifying the  blocksize
 (20)  with  the  b option.  If you want to change the block-
 size, you must change the blocksize arguments  both  on  the
 tar command and on the dd command.

 Now, here is how to use tar to get files from a tape on  the
 remote system back to the local system:
      example% rsh -n host dd if=/dev/rmt/0 bs=20b |
           tar xvBfb - 20 filenames
      messages from tar
      example%

 In the example above, we are  extracting  from  the  tarfile
 with  the  x  key letter, asking for verbose output from tar
 with the v option, telling tar it is  reading  from  a  pipe
 with  the B option, specifying the name of the input tarfile
 using the f option (the standard input is where the  tarfile
 appears,  as  indicated by the `-' sign), and specifying the
 blocksize (20) with the b option.

ENVIRONMENT
If any of the LC_* variables ( LC_CTYPE, LC_MESSAGES,
LC_TIME, LC_COLLATE, LC_NUMERIC, and LC_MONETARY ) (see
environ(5)) are not set in the environment, the operational
behavior of tar for each corresponding locale category is
determined by the value of the LANG environment variable.
If LC_ALL is set, its contents are used to override both the
LANG and the other LC_* variables. If none of the above
variables is set in the environment, the "C" (U.S. style)
locale determines how tar behaves.

 LC_CTYPE
      Determines how tar handles characters. When LC_CTYPE is
      set  to  a valid value, tar can display and handle text
      and filenames  containing  valid  characters  for  that
      locale.  tar  can display and handle Extended Unix code
      (EUC) characters where any individual character can  be
      1,  2, or 3 bytes wide. tar can also handle EUC charac-
      ters of 1, 2, or more column widths. In the "C" locale,
      only characters from ISO 8859-1 are valid.

 LC_MESSAGES
      Determines how diagnostic and informative messages  are
      presented.  This includes the language and style of the
      messages, and the correct form of affirmative and nega-
      tive  responses.   In  the "C" locale, the messages are
      presented in the default  form  found  in  the  program
      itself (in most cases, U.S. English).

 LC_TIME
      Determines how tar handles date and time  formats.   In
      the  "C" locale, date and time handling follow the U.S.
      rules.

FILES
/dev/rmt/[0-7][b][n]
/dev/rmt/[0-7]l[b][n]
/dev/rmt/[0-7]m[b][n]
/dev/rmt/[0-7]h[b][n]
/dev/rmt/[0-7]u[b][n]
/dev/rmt/[0-7]c[b][n]
/etc/default/tar Settings may look like this:
archive0=/dev/rmt/0
archive1=/dev/rmt/0n
archive2=/dev/rmt/1
archive3=/dev/rmt/1n
archive4=/dev/rmt/0
archive5=/dev/rmt/0n
archive6=/dev/rmt/1
archive7=/dev/rmt/1n

 /tmp/tar*

SEE ALSO
ar(1), chown(1), cpio(1), csh(1), ls(1), mt(1), umask(2),
environ(5)

DIAGNOSTICS
Complaints about bad key characters and tape read/write
errors.
Complaints if enough memory is not available to hold the
link tables.

NOTES
There is no way to ask for the n-th occurrence of a file.

 Tape errors are handled ungracefully.

 The u option can be slow.

 The b option should not be used with archives that are going
 to  be  updated.   The  current  magnetic tape driver cannot
 backspace raw magnetic tape.  If the archive is  on  a  disk
 file, the b option should not be used at all, because updat-
 ing an archive stored on disk can destroy it.

 Neither the r option nor the  u  option  can  be  used  with
 quarter-inch  archive  tapes, since these tape drives cannot
 backspace.

 When extracting tapes created with the r or u option, direc-
 tory modification times may not be set correctly.

 When using r,u,x, orX, the named files must match exactly to
 the  corresponding  files  in  the tarfile.  For example, to
 extract ./filename, you must  specify  ./filename,  and  not
 filename.  The t option displays how each file was archived.

 The full pathname length cannot exceed 255 characters.

 The file name (or leaf) length cannot exceed 100 characters.

 The prefix of the pathname cannot exceed 155 characters.

 tar does not copy empty directories or special files such as
 devices.

 Filename substitution wildcards do not work  for  extracting
 files  from  the archive.  To get around this, use a command
 of the form:
      tar xvf... /dev/rmt/0  `tar  tf...  /dev/rmt/0  |  grep
      'pattern'`

The file name (or leaf) length cannot exceed 100 characters.

相关链接：

https://github.com/rubygems/rubygems/blob/master/lib/rubygems/package/tar_writer.rb#L312

ruby/rubygems#1376

https://www.linuxquestions.org/questions/linux-software-2/tar-keeps-reporting-99-character-limit-despite-using-posix-option-4175578854/

MidnightCommander/mc#2201

http://ibgwww.colorado.edu/~lessem/psyc5112/usail/man/solaris/tar.1.html

https://superuser.com/questions/1166820/tar-truncating-file-names-when-tarfile-is-transferred-from-linux-to-unix-solari

[lindexi]

后面可以考虑将超过 100 字符的部分，拆分到前缀里面，这样最长长度能达到 255 字符。这个活需要改动些内容，也要多去测测，现在没啥动力做这个活。加注释和抛出异常说明就好

[lindexi]

由于 tar 有多个版本，官方 gnu 写的不清不楚，不能快速定位到所述问题。不如贴原来那个大学里面的链接，毕竟是从 1997 就在那的链接了，预计会比维基百科等更加稳定