用python封装bash脚本

Question

我刚刚发现了这个很棒的wget包装器，我想使用子流程模块将其重写为python脚本。然而，事实证明这很棘手，给了我各种各样的错误。

download()
{
    local url=$1
    echo -n "    "
    wget --progress=dot $url 2>&1 | grep --line-buffered "%" | 
    sed -u -e "s,.,,g" | awk '{printf("bbbb%4s", $2)}'
    echo -ne "bbbb"
    echo " DONE"
}

然后可以这样称呼：

file="patch-2.6.37.gz"
echo -n "Downloading $file:"
download "http://www.kernel.org/pub/linux/kernel/v2.6/$file"

有什么想法吗？

来源：http://fitnr.com/showing-file-download-progress-using-wget.html

Answer 1

我想你已经不远了。我主要想知道，既然在Python中可以在内部完成所有这些工作，为什么还要在grep、sed和awk中运行管道呢？

#! /usr/bin/env python
import re
import subprocess
TARGET_FILE = "linux-2.6.0.tar.xz"
TARGET_LINK = "http://www.kernel.org/pub/linux/kernel/v2.6/%s" % TARGET_FILE
wgetExecutable = '/usr/bin/wget'
wgetParameters = ['--progress=dot', TARGET_LINK]
wgetPopen = subprocess.Popen([wgetExecutable] + wgetParameters,
                             stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
for line in iter(wgetPopen.stdout.readline, b''):
    match = re.search(r'd+%', line)
    if match:
        print 'bbbb' + match.group(0),
wgetPopen.stdout.close()
wgetPopen.wait()

Answer 2

如果您正在用Python重写脚本；在这种情况下，您可以用urllib.urlretrieve()替换wget：

#!/usr/bin/env python
import os
import posixpath
import sys
import urllib
import urlparse
def url2filename(url):
    """Return basename corresponding to url.
    >>> url2filename('http://example.com/path/to/file?opt=1')
    'file'
    """
    urlpath = urlparse.urlsplit(url).path  # pylint: disable=E1103
    basename = posixpath.basename(urllib.unquote(urlpath))
    if os.path.basename(basename) != basename:
        raise ValueError  # refuse 'dir%5Cbasename.ext' on Windows
    return basename
def reporthook(blocknum, blocksize, totalsize):
    """Report download progress on stderr."""
    readsofar = blocknum * blocksize
    if totalsize > 0:
        percent = readsofar * 1e2 / totalsize
        s = "r%5.1f%% %*d / %d" % (
            percent, len(str(totalsize)), readsofar, totalsize)
        sys.stderr.write(s)
        if readsofar >= totalsize: # near the end
            sys.stderr.write("n")
    else: # total size is unknown
        sys.stderr.write("read %dn" % (readsofar,))
url = sys.argv[1]
filename = sys.argv[2] if len(sys.argv) > 2 else url2filename(url)
urllib.urlretrieve(url, filename, reporthook)

示例：

$ python download-file.py http://example.com/path/to/file 

它将url下载到一个文件中。如果没有给出文件，那么它将使用url中的basename。

如果需要，也可以运行wget：

#!/usr/bin/env python
import sys
from subprocess import Popen, PIPE, STDOUT
def urlretrieve(url, filename=None, width=4):
    destination = ["-O", filename] if filename is not None else []
    p = Popen(["wget"] + destination + ["--progress=dot", url],
              stdout=PIPE, stderr=STDOUT, bufsize=1) # line-buffered (out side)
    for line in iter(p.stdout.readline, b''):
        if b'%' in line: # grep "%"
            line = line.replace(b'.', b'') # sed -u -e "s,.,,g"
            percents = line.split(None, 2)[1].decode() # awk $2
            sys.stderr.write("b"*width + percents.rjust(width))
    p.communicate() # close stdout, wait for child's exit
    print("b"*width + "DONE")
url = sys.argv[1]
filename = sys.argv[2] if len(sys.argv) > 2 else None
urlretrieve(url, filename)

我没有注意到这个代码有任何缓冲问题。

Answer 3

我以前做过这样的事情。我很乐意与您分享我的代码：）

#!/usr/bin/python2.7
# encoding=utf-8
import sys
import os
import datetime
SHEBANG = "#!/bin/bashnn"
def get_cmd(editor='vim', initial_cmd=""):
    from subprocess import call
    from tempfile import NamedTemporaryFile
    # Create the initial temporary file.
    with NamedTemporaryFile(delete=False) as tf:
        tfName = tf.name
        tf.write(initial_cmd)
    # Fire up the editor.
    if call([editor, tfName], shell=False) != 0:
        return None
        # Editor died or was killed.
        # Get the modified content.
    fd = open(tfName)
    res = fd.read()
    fd.close()
    os.remove(tfName)
    return res
def main():
    initial_cmd = "wget " + sys.argv[1]
    cmd  = get_cmd(editor='vim', initial_cmd=initial_cmd)
    if len(sys.argv) > 1 and sys.argv[1] == 's':
        #keep the download infomation.
        t = datetime.datetime.now()
        filename = "swget_%02d%02d%02d%02d%02d" %
                (t.month, t.day, t.hour, t.minute, t.second)
        with open(filename, 'w') as f:
            f.write(SHEBANG)
            f.write(cmd)
            f.close()
            os.chmod(filename, 0777)
    os.system(cmd)
main()

# run this script with the optional argument 's'
# copy the command to the editor, then save and quit. it will 
# begin to download. if you have use the argument 's'.
# then this script will create another executable script, you 
# can use that script to resume you interrupt download.( if server support)

所以，基本上，你只需要修改initial_cmd的值，在你的情况下，它是

wget --progress=dot $url 2>&1 | grep --line-buffered "%" | 
    sed -u -e "s,.,,g" | awk '{printf("bbbb%4s", $2)}'

这个脚本将首先创建一个临时文件，然后在其中放入shell命令，并赋予它执行权限。最后运行带有命令的临时文件。

Answer 4

vim下载.py

#!/usr/bin/env python
import subprocess
import os
sh_cmd = r"""
download()
{
    local url=$1
    echo -n "    "
    wget --progress=dot $url 2>&1 |
        grep --line-buffered "%"  |
        sed -u -e "s,.,,g"       |
        awk '{printf("bbbb%4s", $2)}'
    echo -ne "bbbb"
    echo " DONE"
}
download "http://www.kernel.org/pub/linux/kernel/v2.6/$file"
"""
cmd = 'sh'
p = subprocess.Popen(cmd, 
    shell=True,
    stdin=subprocess.PIPE,
    env=os.environ
)
p.communicate(input=sh_cmd)
# or:
# p = subprocess.Popen(cmd,
#    shell=True,
#    stdin=subprocess.PIPE,
#    env={'file':'xx'})
# 
# p.communicate(input=sh_cmd)
# or:
# p = subprocess.Popen(cmd, shell=True,
#    stdin=subprocess.PIPE,
#    stdout=subprocess.PIPE,
#    stderr=subprocess.PIPE,
#    env=os.environ)
# stdout, stderr = p.communicate(input=sh_cmd)

然后你可以打这样的电话：

file="xxx" python dowload.py

Answer 5

简单地说，考虑到您有script.sh文件，您可以执行它并打印它的返回值（如果有的话）：

import subprocess
process = subprocess.Popen('/path/to/script.sh', shell=True, stdout=subprocess.PIPE)
process.wait()
print process.returncode