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公共字符串 (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 服务器位于此处:ftp://ftp.igsb.uiowa.edu/gis_library/counties/，不需要用户名和密码.所以，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.

我在这里阅读了很多关于 Stack Overflow 的问题和 Python 的文档，但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站点(其中不是必需的)，我不知道如何在 ftplib 或 urllib 中 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.

提前感谢您的帮助

推荐答案

好的，好像可以了.如果尝试下载目录或扫描文件，可能会出现问题.异常处理可以方便地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 无法工作，因为您在远程文件系统上，但您可以使用 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

代码如下:它会下载TEMP目录下所有匹配*DEM*的文件，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 + " ...
")
    #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+" ...
")
            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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