使用Python从包含给定字符串的FTP服务器下载文件

问题描述

我正在尝试从FTP服务器下载大量共享相同字符串(DEM)的文件.这些文件嵌套在多个目录中.例如，Adair/DEM*和Adams/DEM*

I'm trying to download a large number of files that all share a common string (DEM) from an FTP sever. These files are nested inside multiple directories. For example, Adair/DEM* and Adams/DEM*

FTP服务器位于以下位置:ftp://ftp.igsb.uiowa.edu/gis_library/counties/，不需要用户名和密码.因此，我想遍历每个县并下载包含字符串DEM的文件.

The FTP sever is located here: ftp://ftp.igsb.uiowa.edu/gis_library/counties/ and requires no username and password.So, I'd like to go through each county and download the files containing the string DEM.

我在这里已经阅读了许多有关Stack Overflow和Python文档的问题，但是无法弄清楚如何使用ftplib.FTP()在没有用户名和密码的情况下进入网站(这不是必需的)，我可以t弄清楚如何在ftplib或urllib中进行grep或使用glob.glob.

I've read many questions here on Stack Overflow and the documentation from Python, but cannot figure out how to use ftplib.FTP() to get into the site without a username and password (which is not required), and I can't figure out how to grep or use glob.glob inside of ftplib or urllib.

预先感谢您的帮助

推荐答案

好的，看来可以.如果尝试下载目录或扫描文件，可能会出现问题.可以使用异常处理来捕获错误的文件类型并跳过.

Ok, seems to work. There may be issues if trying to download a directory, or scan a file. Exception handling may come handy to trap wrong filetypes and skip.

glob.glob无法使用，因为您使用的是远程文件系统，但是可以使用fnmatch来匹配名称

glob.glob cannot work since you're on a remote filesystem, but you can use fnmatch to match the names

这是代码:它将所有与*DEM*匹配的文件下载到TEMP目录中，并按目录排序.

Here's the code: it download all files matching *DEM* in TEMP directory, sorting by directory.

import ftplib,sys,fnmatch,os

output_root = os.getenv("TEMP")

fc = ftplib.FTP("ftp.igsb.uiowa.edu")
fc.login()
fc.cwd("/gis_library/counties")

root_dirs = fc.nlst()
for l in root_dirs:
    sys.stderr.write(l + " ...\n")
    #print(fc.size(l))
    dir_files = fc.nlst(l)
    local_dir = os.path.join(output_root,l)
    if not os.path.exists(local_dir):
        os.mkdir(local_dir)

    for f in dir_files:
        if fnmatch.fnmatch(f,"*DEM*"):   # cannot use glob.glob
            sys.stderr.write("downloading "+l+"/"+f+" ...\n")
            local_filename = os.path.join(local_dir,f)
            with open(local_filename, 'wb') as fh:
                fc.retrbinary('RETR '+ l + "/" + f, fh.write)

fc.close()

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