To count the number of archive members in a zip archive in Python:
#!/usr/bin/env python
import sys
from contextlib import closing
from zipfile import ZipFile
with closing(ZipFile(sys.argv[1])) as archive:
count = len(archive.infolist())
print(count)
It may use zlib, bz2, lzma modules if available, to decompress the archive.
To count the number of regular files in a tar archive:
#!/usr/bin/env python
import sys
import tarfile
with tarfile.open(sys.argv[1]) as archive:
count = sum(1 for member in archive if member.isreg())
print(count)
It may support gzip, bz2 and lzma compression depending on version of Python.
You could find a 3rd-party module that would provide a similar functionality for 7z archives.
To get the number of files in an archive using 7z utility:
import os
import subprocess
def count_files_7z(archive):
s = subprocess.check_output(["7z", "l", archive], env=dict(os.environ, LC_ALL="C"))
return int(re.search(br'(\d+)\s+files,\s+\d+\s+folders$', s).group(1))
Here's version that may use less memory if there are many files in the archive:
import os
import re
from subprocess import Popen, PIPE, CalledProcessError
def count_files_7z(archive):
command = ["7z", "l", archive]
p = Popen(command, stdout=PIPE, bufsize=1, env=dict(os.environ, LC_ALL="C"))
with p.stdout:
for line in p.stdout:
if line.startswith(b'Error:'): # found error
error = line + b"".join(p.stdout)
raise CalledProcessError(p.wait(), command, error)
returncode = p.wait()
assert returncode == 0
return int(re.search(br'(\d+)\s+files,\s+\d+\s+folders', line).group(1))
Example:
import sys
try:
print(count_files_7z(sys.argv[1]))
except CalledProcessError as e:
getattr(sys.stderr, 'buffer', sys.stderr).write(e.output)
sys.exit(e.returncode)
To count the number of lines in the output of a generic subprocess:
from functools import partial
from subprocess import Popen, PIPE, CalledProcessError
p = Popen(command, stdout=PIPE, bufsize=-1)
with p.stdout:
read_chunk = partial(p.stdout.read, 1 << 15)
count = sum(chunk.count(b'\n') for chunk in iter(read_chunk, b''))
if p.wait() != 0:
raise CalledProcessError(p.returncode, command)
print(count)
It supports unlimited output.
Could you explain why buffsize=-1 (as opposed to buffsize=1 in your previous answer: stackoverflow.com/a/30984882/281545)
bufsize=-1 means use the default I/O buffer size instead of bufsize=0 (unbuffered) on Python 2. It is a performance boost on Python 2. It is default on the recent Python 3 versions. You might get a short read (lose data) if on some earlier Python 3 versions where bufsize is not changed to bufsize=-1.
This answer reads in chunks and therefore the stream is fully buffered for efficiency. The solution you've linked is line-oriented. bufsize=1 means "line buffered". There is minimal difference from bufsize=-1 otherwise.
and also what the read_chunk = partial(p.stdout.read, 1 << 15) buys us ?
It is equivalent to read_chunk = lambda: p.stdout.read(1<<15) but provides more introspection in general. It is used to implement wc -l in Python efficiently.
