import re
file = """Mon Feb 19 22:25:19 2018 ABC.ls:9999: some text here, Mon Feb 19 22:25:19 2017
Mon Feb 19 22:25:20 2018 ABC.ls:9999: some text here
Mon Feb 19 22:25:20 2018 ABC.ls:9999: some text here, () with some more text"""
rx = re.compile(r'(?:Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s\d{2}\s\d{2}:\d{2}:\d{2}\s\d{4}')
res = []
for s in file.splitlines():
m = rx.search(s)
if m:
res.append(m.group())
print(res)
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