从文件中的行读取多个子字符串

Question

So essentially what I am doing is making a report from an apache error_log file using python scripting. An example of what I am dealing with is:

[Wed Apr 13 18:33:42.521106 2016] [core:notice] [pid 11690] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
[Wed Apr 13 18:33:42.543989 2016] [suexec:notice] [pid 11690] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)

The end result which I'm trying to get would look something like:

core:notice - SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
suexec:notice - AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)

which is the error type followed by the trailing text. I then need to write this formatted text into a new file.

I've been trying to use Regular Expressions to do this but it's been years since I used python at all, and have never used regular expressions before. The most I've been able to get thus far is isolating the first (date) section, but I cannot figure out how to get subsequent bracket surrounded substrings and the trailing text. Any and all help would be greatly appreciated!

Answer 1

Since your data consist of exactly four fields and are shown with nice squared bracket per field except the last one, you could take advantages from those behaviors to do your task without using Regex like this:

texts = ['[Wed Apr 13 18:33:42.521106 2016] [core:notice] [pid 11690] SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0', \
'[Wed Apr 13 18:33:42.543989 2016] [suexec:notice] [pid 11690] AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)']
for text in texts:
    words = text.replace('[','').split(']')
    newWords = words[1] + ' -' + words[3]
    print(newWords)

Resulting in:

 core:notice - SELinux policy enabled; httpd running as context system_u:system_r:httpd_t:s0
 suexec:notice - AH01232: suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)

The idea is to first replace one the starting squared bracket with empty string and use the closing squared bracket as the parameter to split your word (thus will be removed too):

words = text.replace('[','').split(']')

Then you simply need to combine the fields which you want to form your new string from:

newWords = words[1] + ' -' + words[3]

And you are done.