如果你想要一些明显(不需要在手册中查找深奥的东西)不需要导入就可以工作的东西，请尝试/except，并且可以在相当大范围的Python 2上工作。X版本(2.2至2.6):

def headn(file_name, n):
    """Like *x head -N command"""
    result = []
    nlines = 0
    assert n >= 1
    for line in open(file_name):
        result.append(line)
        nlines += 1
        if nlines >= n:
            break
    return result

if __name__ == "__main__":
    import sys
    rval = headn(sys.argv[1], int(sys.argv[2]))
    print rval
    print len(rval)

如果你想快速读取第一行并且不关心性能，你可以使用.readlines()返回列表对象，然后对列表进行切片。

例如，前5行:

with open("pathofmyfileandfileandname") as myfile:
    firstNlines=myfile.readlines()[0:5] #put here the interval you want

注意:整个文件是读取的，所以不是最好的从性能的角度来看，但它 是易于使用，快速编写和易于记忆，所以如果你只是想执行 一些一次性计算非常方便

print firstNlines

与其他答案相比，一个优点是可以轻松地选择行范围，例如跳过前10行[10:30]或最后10行[:-10]或只选择偶数行[::2]。

fname = input("Enter file name: ")
num_lines = 0

with open(fname, 'r') as f: #lines count
    for line in f:
        num_lines += 1

num_lines_input = int (input("Enter line numbers: "))

if num_lines_input <= num_lines:
    f = open(fname, "r")
    for x in range(num_lines_input):
        a = f.readline()
        print(a)

else:
    f = open(fname, "r")
    for x in range(num_lines_input):
        a = f.readline()
        print(a)
        print("Don't have", num_lines_input, " lines print as much as you can")


print("Total lines in the text",num_lines)

有一个简单的方法来获取前10行:

with open('fileName.txt', mode = 'r') as file:
    list = [line.rstrip('\n') for line in file][:10]
    print(list)

基于gnibbler的投票结果(2009年11月20日0:27):这个类将head()和tail()方法添加到文件对象。

class File(file):
    def head(self, lines_2find=1):
        self.seek(0)                            #Rewind file
        return [self.next() for x in xrange(lines_2find)]

    def tail(self, lines_2find=1):  
        self.seek(0, 2)                         #go to end of file
        bytes_in_file = self.tell()             
        lines_found, total_bytes_scanned = 0, 0
        while (lines_2find+1 > lines_found and
               bytes_in_file > total_bytes_scanned): 
            byte_block = min(1024, bytes_in_file-total_bytes_scanned)
            self.seek(-(byte_block+total_bytes_scanned), 2)
            total_bytes_scanned += byte_block
            lines_found += self.read(1024).count('\n')
        self.seek(-total_bytes_scanned, 2)
        line_list = list(self.readlines())
        return line_list[-lines_2find:]

用法:

f = File('path/to/file', 'r')
f.head(3)
f.tail(3)

这适用于Python 2和3:

from itertools import islice

with open('/tmp/filename.txt') as inf:
    for line in islice(inf, N, N+M):
        print(line)