python3 读取文件的最后一行非空行

约定不等于承诺〃 2021-08-29 19:38 656阅读 0赞

利用Python读取文件（针对大文件和小文件两种）的首行（第一行）和末行（最后一行）。脚本借鉴了前人的两种处理思路（在下面的脚本中有注释说明引用出处），并修正了原先两种处理方法中如果文件末尾含有多个空行而返回空行的问题。

脚本内容可以从GitHub上获取：

[https://github.com/DingGuodong/LinuxBashShellScriptForOps/blob/master/functions/file/getFileLastLine.py][https_github.com_DingGuodong_LinuxBashShellScriptForOps_blob_master_functions_file_getFileLastLine.py]

脚本内容如下：

#!/usr/bin/python
    # encoding: utf-8
    # -*- coding: utf8 -*-
    import os
     
     
    # Refer: http://www.pythonclub.org/python-files/last-line
    def get_last_line(inputfile):
        filesize = os.path.getsize(inputfile)
        blocksize = 1024
        dat_file = open(inputfile, 'rb')
        last_line = ""
        if filesize > blocksize:
            maxseekpoint = (filesize // blocksize)
            dat_file.seek((maxseekpoint - 1) * blocksize)
        elif filesize:
            # maxseekpoint = blocksize % filesize
            dat_file.seek(0, 0)
        lines = dat_file.readlines()
        if lines:
            last_line = lines[-1].strip()
        # print "last line : ", last_line
        dat_file.close()
        return last_line
     
     
    # Refer: http://code.activestate.com/recipes/578095/
    def print_first_last_line(inputfile):
        filesize = os.path.getsize(inputfile)
        blocksize = 1024
        dat_file = open(inputfile, 'rb')
        headers = dat_file.readline().strip()
        if filesize > blocksize:
            maxseekpoint = (filesize // blocksize)
            dat_file.seek(maxseekpoint * blocksize)
        elif filesize:
            maxseekpoint = blocksize % filesize
            dat_file.seek(maxseekpoint)
        lines = dat_file.readlines()
        if lines:
            last_line = lines[-1].strip()
        # print "first line : ", headers
        # print "last line : ", last_line
        return headers, last_line
     
     
    # My Implementation
    def get_file_last_line(inputfile):
        filesize = os.path.getsize(inputfile)
        blocksize = 1024
        with open(inputfile, 'rb') as f:
            last_line = ""
            if filesize > blocksize:
                maxseekpoint = (filesize // blocksize)
                f.seek((maxseekpoint - 1) * blocksize)
            elif filesize:
                f.seek(0, 0)
            lines = f.readlines()
            if lines:
                lineno = 1
                while last_line == "":
                    last_line = lines[-lineno].strip()
                    lineno += 1
            return last_line

[https_github.com_DingGuodong_LinuxBashShellScriptForOps_blob_master_functions_file_getFileLastLine.py]: https://yq.aliyun.com/go/articleRenderRedirect?url=https%3A%2F%2Fgithub.com%2FDingGuodong%2FLinuxBashShellScriptForOps%2Fblob%2Fmaster%2Ffunctions%2Ffile%2FgetFileLastLine.py