first_line = next(open(filename))

如果你想读取file。txt

line1 helloworld

import linecache
# read first line
print(linecache.getline('file.txt'), 1)
>helloworld

要返回打开文件的开头，然后返回第一行，请执行以下操作:

my_file.seek(0)
first_line = my_file.readline()

这应该做到:

f = open('myfile.txt')
first = f.readline()

infile = open('filename.txt', 'r')
firstLine = infile.readline()

first_line = next(open(filename))