通过python匹配和显示特定行

Question

I have 15 lines in a log file and i want to read the 4th and 10 th line for example through python and display them on output saying this string is found :

abc
def
aaa
aaa
aasd
dsfsfs
dssfsd
sdfsds
sfdsf
ssddfs
sdsf
f
dsf
s
d

please suggest through code how to achieve this in python .

just to elaborate more on this example the first (string or line is unique) and can be found easily in logfile the next String B comes within 40 lines of the first one but this one occurs at lots of places in the log file so i need to read this string withing the first 40 lines after reading string A and print the same that these strings were found.

Also I cant use with command of python as this gives me errors like 'with' will become a reserved keyword in Python 2.6. I am using Python 2.5

Answer 1

You can use this:

fp = open("file")
for i, line in enumerate(fp):
    if i == 3:
        print line
    elif i == 9:
        print line
        break
fp.close()

Answer 2

#list of random characters
from random import randint
a = list(chr(randint(0,100)) for x in xrange(100))
#look for this
lookfor = 'b'
for element in xrange(100):
    if lookfor==a[element]:
        print a[element],'on',element
#b on 33
#b on 34

is one easy to read and simple way to do it. Can you give part of your log file as an example? There are other ways that may work better :).

---

after edits by author:

The easiest thing you can do then is:

looking_for = 'findthis' i = 1 for line in open('filename.txt','r'):
    if looking_for == line:
        print i, line
    i+=1

it's efficient and easy :)

Answer 3

def bar(start,end,search_term):
    with open("foo.txt") as fil:
        if search_term in fil.readlines()[start,end]:
            print search_term + " has found" 


>>>bar(4, 10, "dsfsfs")
"dsfsfs has found"