Docs/Python/查看文件最后几行.html
2022-10-18 16:59:37 +08:00

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<title>查看文件最后几行</title>
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font-weight: bold;
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<h1 class="title" id="leanote-title">查看文件最后几行</h1>
<div class="content-html" id="leanote-content"><pre id="leanote_ace_1494556701760_0" class="brush:python ace-tomorrow ace_focus"># coding=utf-8
import sys
import time
class Tail():
def __init__(self,file_name,callback=sys.stdout.write):
self.file_name = file_name
self.callback = callback
def follow(self,n=10):
try:
with open(self.file_name) as f:
self._file = f
self._file.seek(0,2)
self.file_length = self._file.tell()
self.showLastLine(n)
while True:
line = self._file.readline()
if line:
self.callback(line)
time.sleep(1)
except Exception,e:
print '打开文件失败,囧,看看文件是不是不存在,或者权限有问题'
print e
def showLastLine(self, n):
len_line = 100
read_len = len_line*n
while True:
if read_len&gt;self.file_length:
self._file.seek(0)
last_lines = self._file.read().split('\n')[-n:]
break
self._file.seek(-read_len, 2)
last_words = self._file.read(read_len)
count = last_words.count('\n')
if count&gt;=n:
last_lines = last_words.split('\n')[-n:]
break
else:
if count==0:
len_perline = read_len
else:
len_perline = read_len/count
read_len = len_perline * n
for line in last_lines:
self.callback(line+'\n')
if __name__ == '__main__':
py_tail = Tail('test.txt')
py_tail.follow()
</pre><p><br data-mce-bogus="1"></p></div>
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