在 python 脚本中读取 tar 文件内容而不解压它

Question

我有一个 tar 文件，其中包含许多文件。 我需要编写一个 python 脚本，它将读取文件的内容并给出总字符数，包括字母总数、空格、换行符等所有内容，而无需解压 tar 文件。

Answer 1

您可以使用 getmembers()

>>> import  tarfile
>>> tar = tarfile.open("test.tar")
>>> tar.getmembers()

之后，您可以使用 extractfile() 将成员提取为文件对象。仅举一个例子

import tarfile,os
import sys
os.chdir("/tmp/foo")
tar = tarfile.open("test.tar")
for member in tar.getmembers():
    f=tar.extractfile(member)
    content=f.read()
    print "%s has %d newlines" %(member, content.count("\n"))
    print "%s has %d spaces" % (member,content.count(" "))
    print "%s has %d characters" % (member, len(content))
    sys.exit()
tar.close()

对于上面示例中的文件对象 f，您可以使用 read()、readlines() 等。

Answer 2

您需要使用 tarfile 模块。具体来说，您使用 TarFile 类的实例来访问文件，然后使用 TarFile.getnames() 访问名称。

 |  getnames(self)
 |      Return the members of the archive as a list of their names. It has
 |      the same order as the list returned by getmembers().

如果您想读取内容，则可以使用此方法

 |  extractfile(self, member)
 |      Extract a member from the archive as a file object. `member' may be
 |      a filename or a TarInfo object. If `member' is a regular file, a
 |      file-like object is returned. If `member' is a link, a file-like
 |      object is constructed from the link's target. If `member' is none of
 |      the above, None is returned.
 |      The file-like object is read-only and provides the following
 |      methods: read(), readline(), readlines(), seek() and tell()

Answer 3

之前，这篇文章展示了一个“dict(zip(()”) 将成员名称和成员列表放在一起的示例，这很愚蠢，会导致过度读取存档，为了实现相同的目的，我们可以使用字典理解：

index = {i.name: i for i in my_tarfile.getmembers()}

---

更多信息关于如何使用 tarfile

提取 tarfile 成员

#!/usr/bin/env python3
import tarfile

my_tarfile = tarfile.open('/path/to/mytarfile.tar')

print(my_tarfile.extractfile('./path/to/file.png').read())

索引 tar 文件

#!/usr/bin/env python3
import tarfile
import pprint

my_tarfile = tarfile.open('/path/to/mytarfile.tar')

index = my_tarfile.getnames()  # a list of strings, each members name
# or
# index = {i.name: i for i in my_tarfile.getmembers()}

pprint.pprint(index)

索引、读取、动态额外

#!/usr/bin/env python3

import tarfile
import base64
import textwrap
import random

# note, indexing a tar file requires reading it completely once
# if we want to do anything after indexing it, it must be a file
# that can be seeked (not a stream), so here we open a file we
# can seek
my_tarfile = tarfile.open('/path/to/mytar.tar')


# tarfile.getmembers is similar to os.stat kind of, it will
# give you the member names (i.name) as well as TarInfo attributes:
#
# chksum,devmajor,devminor,gid,gname,linkname,linkpath,
# mode,mtime,name,offset,offset_data,path,pax_headers,
# size,sparse,tarfile,type,uid,uname
#
# here we use a dictionary comprehension to index all TarInfo
# members by the member name
index = {i.name: i for i in my_tarfile.getmembers()}

print(index.keys())

# pick your member
# note: if you can pick your member before indexing the tar file,
# you don't need to index it to read that file, you can directly
# my_tarfile.extractfile(name)
# or my_tarfile.getmember(name)

# pick your filename from the index dynamically
my_file_name = random.choice(index.keys())

my_file_tarinfo = index[my_file_name]
my_file_size = my_file_tarinfo.size
my_file_buf = my_tarfile.extractfile( 
    my_file_name
    # or my_file_tarinfo
)

print('file_name: {}'.format(my_file_name))
print('file_size: {}'.format(my_file_size))
print('----- BEGIN FILE BASE64 -----'
print(
    textwrap.fill(
        base64.b64encode(
            my_file_buf.read()
        ).decode(),
        72
    )
)
print('----- END FILE BASE64 -----'

包含重复成员的 tar 文件 tarfile

在我们有一个奇怪创建的 tar 的情况下，在本例中通过附加同一文件的多个版本对于同一个 tar 存档，我们可以仔细处理它，我已经注释了哪些成员包含哪些文本，假设我们想要第四个（索引 3）成员，“capturetheflag\n”

tar -tf mybadtar.tar 
mymember.txt  # "version 1\n"
mymember.txt  # "version 1\n"
mymember.txt  # "version 2\n"
mymember.txt  # "capturetheflag\n"
mymember.txt  # "version 3\n"

#!/usr/bin/env python3

import tarfile
my_tarfile = tarfile.open('mybadtar.tar')

# >>> my_tarfile.getnames()
# ['mymember.txt', 'mymember.txt', 'mymember.txt', 'mymember.txt', 'mymember.txt']

# if we use extracfile on a name, we get the last entry, I'm not sure how python is smart enough to do this, it must read the entire tar file and buffer every valid member and return the last one

# >>> my_tarfile.extractfile('mymember.txt').read()
# b'version 3\n'

# >>> my_tarfile.extractfile(my_tarfile.getmembers()[3]).read()
# b'capturetheflag\n'

或者我们可以迭代 tar 文件
#!/usr/bin/env python3

import tarfile
my_tarfile = tarfile.open('mybadtar.tar')
# note, if we do anything to the tarfile object that will 
# cause a full read, the tarfile.next() method will return none,
# so call next in a loop as the first thing you do if you want to
# iterate

while True:
    my_member = my_tarfile.next()
    if not my_member:
        break
    print((my_member.offset, mytarfile.extractfile(my_member).read,))

# (0, b'version 1\n')
# (1024, b'version 1\n')
# (2048, b'version 2\n')
# (3072, b'capturetheflag\n')
# (4096, b'version 3\n')


    

Answer 4

 import tarfile

 targzfile = "path to the file"

 tar = tarfile.open(targzfile)

 for item in tar.getnames():

     if "README.txt" in item:

       file_content = tar.extractfile(item).read()

       fileout = open("output file path", 'wb')

       fileout.write(file_content)

       fileout.close()

       break

Answer 5

你可以使用 tarfile.list()
ex :

filename = "abc.tar.bz2"
with open( filename , mode='r:bz2') as f1:
    print(f1.list())

获取这些数据后。您可以操纵此输出或将其写入文件并执行您的任何要求。

Answer 6

您可以使用 getnames()

下面是您可以使用的代码示例：

import tarfile
tar_open = tarfile.open("filename.tar")
contents = tar_open.getnames()

# contents will contain a list of filenames inside filename.tar
print(contents)