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Archive::Tar(3)
NAME
Archive::Tar - module for manipulations of tar archives
SYNOPSIS
use Archive::Tar;
my $tar = Archive::Tar->new;
$tar->read('origin.tgz',1);
$tar->extract();
$tar->add_files('file/foo.pl', 'docs/README');
$tar->add_data('file/baz.txt', 'This is the contents now');
$tar->rename('oldname', 'new/file/name');
$tar->write('files.tar');
DESCRIPTION
Archive::Tar provides an object oriented mechanism for handling tar files.
It provides class methods for quick and easy files handling while also
allowing for the creation of tar file objects for custom manipulation. If
you have the IO::Zlib module installed, Archive::Tar will also support
compressed or gzipped tar files.
An object of class Archive::Tar represents a .tar(.gz) archive full of
files and things.
Object Methods
Archive::Tar->new( [$file, $compressed] )
Returns a new Tar object. If given any arguments, "new()" calls the
"read()" method automatically, passing on the arguments provided to the
"read()" method.
If "new()" is invoked with arguments and the "read()" method fails for any
reason, "new()" returns undef.
$tar->read ( $filename|$handle, $compressed, {opt => 'val'} )
Read the given tar file into memory. The first argument can either be the
name of a file or a reference to an already open filehandle (or an IO::Zlib
object if it's compressed) The second argument indicates whether the file
referenced by the first argument is compressed.
The "read" will replace any previous content in $tar!
The second argument may be considered optional if IO::Zlib is installed,
since it will transparently Do The Right Thing. Archive::Tar will warn if
you try to pass a compressed file if IO::Zlib is not available and simply
return.
The third argument can be a hash reference with options. Note that all
options are case-sensitive.
limit
Do not read more than "limit" files. This is useful if you have very
big archives, and are only interested in the first few files.
extract
If set to true, immediately extract entries when reading them. This
gives you the same memory break as the "extract_archive" function.
Note however that entries will not be read into memory, but written
straight to disk.
All files are stored internally as "Archive::Tar::File" objects. Please
consult the Archive::Tar::File documentation for details.
Returns the number of files read in scalar context, and a list of
"Archive::Tar::File" objects in list context.
$tar->contains_file( $filename )
Check if the archive contains a certain file. It will return true if the
file is in the archive, false otherwise.
Note however, that this function does an exact match using "eq" on the full
path. So it cannot compensate for case-insensitive file- systems or compare
2 paths to see if they would point to the same underlying file.
$tar->extract( [@filenames] )
Write files whose names are equivalent to any of the names in @filenames to
disk, creating subdirectories as necessary. This might not work too well
under VMS. Under MacPerl, the file's modification time will be converted
to the MacOS zero of time, and appropriate conversions will be done to the
path. However, the length of each element of the path is not inspected to
see whether it's longer than MacOS currently allows (32 characters).
If "extract" is called without a list of file names, the entire contents of
the archive are extracted.
Returns a list of filenames extracted.
$tar->extract_file( $file, [$extract_path] )
Write an entry, whose name is equivalent to the file name provided to disk.
Optionally takes a second parameter, which is the full (unix) path
(including filename) the entry will be written to.
For example:
$tar->extract_file( 'name/in/archive', 'name/i/want/to/give/it' );
Returns true on success, false on failure.
$tar->list_files( [\@properties] )
Returns a list of the names of all the files in the archive.
If "list_files()" is passed an array reference as its first argument it
returns a list of hash references containing the requested properties of
each file. The following list of properties is supported: name, size,
mtime (last modified date), mode, uid, gid, linkname, uname, gname,
devmajor, devminor, prefix.
Passing an array reference containing only one element, 'name', is special
cased to return a list of names rather than a list of hash references,
making it equivalent to calling "list_files" without arguments.
$tar->get_files( [@filenames] )
Returns the "Archive::Tar::File" objects matching the filenames provided.
If no filename list was passed, all "Archive::Tar::File" objects in the
current Tar object are returned.
Please refer to the "Archive::Tar::File" documentation on how to handle
these objects.
$tar->get_content( $file )
Return the content of the named file.
$tar->replace_content( $file, $content )
Make the string $content be the content for the file named $file.
$tar->rename( $file, $new_name )
Rename the file of the in-memory archive to $new_name.
Note that you must specify a Unix path for $new_name, since per tar
standard, all files in the archive must be Unix paths.
Returns true on success and false on failure.
$tar->remove (@filenamelist)
Removes any entries with names matching any of the given filenames from the
in-memory archive. Returns a list of "Archive::Tar::File" objects that
remain.
$tar->clear
"clear" clears the current in-memory archive. This effectively gives you a
'blank' object, ready to be filled again. Note that "clear" only has effect
on the object, not the underlying tarfile.
$tar->write ( [$file, $compressed, $prefix] )
Write the in-memory archive to disk. The first argument can either be the
name of a file or a reference to an already open filehandle (a GLOB
reference). If the second argument is true, the module will use IO::Zlib to
write the file in a compressed format. If IO::Zlib is not available, the
"write" method will fail and return.
Note that when you pass in a filehandle, the compression argument is
ignored, as all files are printed verbatim to your filehandle. If you wish
to enable compression with filehandles, use an "IO::Zlib" filehandle
instead.
Specific levels of compression can be chosen by passing the values 2
through 9 as the second parameter.
The third argument is an optional prefix. All files will be tucked away in
the directory you specify as prefix. So if you have files 'a' and 'b' in
your archive, and you specify 'foo' as prefix, they will be written to the
archive as 'foo/a' and 'foo/b'.
If no arguments are given, "write" returns the entire formatted archive as
a string, which could be useful if you'd like to stuff the archive into a
socket or a pipe to gzip or something.
$tar->add_files( @filenamelist )
Takes a list of filenames and adds them to the in-memory archive.
The path to the file is automatically converted to a Unix like equivalent
for use in the archive, and, if on MacOS, the file's modification time is
converted from the MacOS epoch to the Unix epoch. So tar archives created
on MacOS with Archive::Tar can be read both with tar on Unix and
applications like suntar or Stuffit Expander on MacOS.
Be aware that the file's type/creator and resource fork will be lost, which
is usually what you want in cross-platform archives.
Returns a list of "Archive::Tar::File" objects that were just added.
$tar->add_data ( $filename, $data, [$opthashref] )
Takes a filename, a scalar full of data and optionally a reference to a
hash with specific options.
Will add a file to the in-memory archive, with name $filename and content
$data. Specific properties can be set using $opthashref. The following
list of properties is supported: name, size, mtime (last modified date),
mode, uid, gid, linkname, uname, gname, devmajor, devminor, prefix. (On
MacOS, the file's path and modification times are converted to Unix
equivalents.)
Returns the "Archive::Tar::File" object that was just added, or "undef" on
failure.
$tar->error( [$BOOL] )
Returns the current errorstring (usually, the last error reported). If a
true value was specified, it will give the "Carp::longmess" equivalent of
the error, in effect giving you a stacktrace.
For backwards compatibility, this error is also available as
$Archive::Tar::error although it is much recommended you use the method
call instead.
$bool = $tar->has_io_string
Returns true if we currently have "IO::String" support loaded.
Either "IO::String" or "perlio" support is needed to support writing
stringified archives. Currently, "perlio" is the preffered method, if
available.
See the "GLOBAL VARIABLES" section to see how to change this preference.
$bool = $tar->has_perlio
Returns true if we currently have "perlio" support loaded.
This requires "perl-5.8" or higher, compiled with "perlio"
Either "IO::String" or "perlio" support is needed to support writing
stringified archives. Currently, "perlio" is the preffered method, if
available.
See the "GLOBAL VARIABLES" section to see how to change this preference.
Class Methods
Archive::Tar->create_archive($file, $compression, @filelist)
Creates a tar file from the list of files provided. The first argument can
either be the name of the tar file to create or a reference to an open file
handle (e.g. a GLOB reference).
The second argument specifies the level of compression to be used, if any.
Compression of tar files requires the installation of the IO::Zlib module.
Specific levels of compression may be requested by passing a value between
2 and 9 as the second argument. Any other value evaluating as true will
result in the default compression level being used.
Note that when you pass in a filehandle, the compression argument is
ignored, as all files are printed verbatim to your filehandle. If you wish
to enable compression with filehandles, use an "IO::Zlib" filehandle
instead.
The remaining arguments list the files to be included in the tar file.
These files must all exist. Any files which don't exist or can't be read
are silently ignored.
If the archive creation fails for any reason, "create_archive" will return
false. Please use the "error" method to find the cause of the failure.
Note that this method does not write "on the fly" as it were; it still
reads all the files into memory before writing out the archive. Consult
the FAQ below if this is a problem.
Archive::Tar->list_archive ($file, $compressed, [\@properties])
Returns a list of the names of all the files in the archive. The first
argument can either be the name of the tar file to list or a reference to
an open file handle (e.g. a GLOB reference).
If "list_archive()" is passed an array reference as its third argument it
returns a list of hash references containing the requested properties of
each file. The following list of properties is supported: name, size,
mtime (last modified date), mode, uid, gid, linkname, uname, gname,
devmajor, devminor, prefix.
Passing an array reference containing only one element, 'name', is special
cased to return a list of names rather than a list of hash references.
Archive::Tar->extract_archive ($file, $gzip)
Extracts the contents of the tar file. The first argument can either be
the name of the tar file to create or a reference to an open file handle
(e.g. a GLOB reference). All relative paths in the tar file will be
created underneath the current working directory.
"extract_archive" will return a list of files it extracted. If the archive
extraction fails for any reason, "extract_archive" will return false.
Please use the "error" method to find the cause of the failure.
Archive::Tar->can_handle_compressed_files
A simple checking routine, which will return true if "Archive::Tar" is able
to uncompress compressed archives on the fly with "IO::Zlib", or false if
"IO::Zlib" is not installed.
You can use this as a shortcut to determine whether "Archive::Tar" will do
what you think before passing compressed archives to its "read" method.
GLOBAL VARIABLES
$Archive::Tar::FOLLOW_SYMLINK
Set this variable to 1 to make "Archive::Tar" effectively make a copy of
the file when extracting. Default is 0, which means the symlink stays
intact. Of course, you will have to pack the file linked to as well.
This option is checked when you write out the tarfile using "write" or
"create_archive".
This works just like "/bin/tar"'s "-h" option.
$Archive::Tar::CHOWN
By default, "Archive::Tar" will try to "chown" your files if it is able to.
In some cases, this may not be desired. In that case, set this variable to
0 to disable "chown"-ing, even if it were possible.
The default is 1.
$Archive::Tar::CHMOD
By default, "Archive::Tar" will try to "chmod" your files to whatever mode
was specified for the particular file in the archive. In some cases, this
may not be desired. In that case, set this variable to 0 to disable
"chmod"-ing.
The default is 1.
$Archive::Tar::DO_NOT_USE_PREFIX
By default, "Archive::Tar" will try to put paths that are over 100
characters in the "prefix" field of your tar header. However, some older
tar programs do not implement this spec. To retain compatibility with these
older versions, you can set the $DO_NOT_USE_PREFIX variable to a true
value, and "Archive::Tar" will use an alternate way of dealing with paths
over 100 characters by using the "GNU Extended Header" feature.
The default is 0.
$Archive::Tar::DEBUG
Set this variable to 1 to always get the "Carp::longmess" output of the
warnings, instead of the regular "carp". This is the same message you would
get by doing:
$tar->error(1);
Defaults to 0.
$Archive::Tar::WARN
Set this variable to 0 if you do not want any warnings printed. Personally
I recommend against doing this, but people asked for the option. Also, be
advised that this is of course not threadsafe.
Defaults to 1.
$Archive::Tar::error
Holds the last reported error. Kept for historical reasons, but its use is
very much discouraged. Use the "error()" method instead:
warn $tar->error unless $tar->extract;
$Archive::Tar::HAS_PERLIO
This variable holds a boolean indicating if we currently have "perlio"
support loaded. This will be enabled for any perl greater than 5.8 compiled
with "perlio".
If you feel strongly about disabling it, set this variable to "false". Note
that you will then need "IO::String" installed to support writing
stringified archives.
Don't change this variable unless you really know what you're doing.
$Archive::Tar::HAS_IO_STRING
This variable holds a boolean indicating if we currently have "IO::String"
support loaded. This will be enabled for any perl that has a loadable
"IO::String" module.
If you feel strongly about disabling it, set this variable to "false". Note
that you will then need "perlio" support from your perl to be able to
write stringified archives.
Don't change this variable unless you really know what you're doing.
FAQ
What's the minimum perl version required to run Archive::Tar?
You will need perl version 5.005_03 or newer.
Isn't Archive::Tar slow?
Yes it is. It's pure perl, so it's a lot slower then your "/bin/tar"
However, it's very portable. If speed is an issue, consider using
"/bin/tar" instead.
Isn't Archive::Tar heavier on memory than /bin/tar?
Yes it is, see previous answer. Since "Compress::Zlib" and therefore
"IO::Zlib" doesn't support "seek" on their filehandles, there is little
choice but to read the archive into memory. This is ok if you want to
do in-memory manipulation of the archive. If you just want to extract,
use the "extract_archive" class method instead. It will optimize and
write to disk immediately.
Can't you lazy-load data instead?
No, not easily. See previous question.
How much memory will an X kb tar file need?
Probably more than X kb, since it will all be read into memory. If this
is a problem, and you don't need to do in memory manipulation of the
archive, consider using "/bin/tar" instead.
What do you do with unsupported filetypes in an archive?
"Unix" has a few filetypes that aren't supported on other platforms,
like "Win32". If we encounter a "hardlink" or "symlink" we'll just try
to make a copy of the original file, rather than throwing an error.
This does require you to read the entire archive in to memory first,
since otherwise we wouldn't know what data to fill the copy with.
(This means that you cannot use the class methods on archives that have
incompatible filetypes and still expect things to work).
For other filetypes, like "chardevs" and "blockdevs" we'll warn that
the extraction of this particular item didn't work.
TODO
Check if passed in handles are open for read/write
Currently I don't know of any portable pure perl way to do this.
Suggestions welcome.
AUTHOR
This module by Jos Boumans <kane@cpan.org>.
ACKNOWLEDGEMENTS
Thanks to Sean Burke, Chris Nandor, Chip Salzenberg, Tim Heaney and
especially Andrew Savige for their help and suggestions.
COPYRIGHT
This module is copyright (c) 2002 Jos Boumans <kane@cpan.org>. All rights
reserved.
This library is free software; you may redistribute and/or modify it under
the same terms as Perl itself.
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