df1['OS Version'].str.contains(MATCH_PATT)

df1[~df1['Aux Site'].str.contains('VCAD')]

import pandas as pd

MATCH_PATT = "AIX|CentOS|Fedora|RHEL|SunOS|SuSE|Ubuntu|(?<!?)?(?!?)"
COLUMN_NAMES = ['Hostname', 'IP Address', 'Aux Site', 'OS Version']
df1 = pd.read_csv('/home/karn/plura/Test/Python_Panda/CyberArk/host.txt', delimiter = "t", usecols=COLUMN_NAMES, encoding='cp1252',  dtype='unicode')
df2 = df1[df1['OS Version'].str.contains(MATCH_PATT,  na=False)][['Hostname', 'IP Address', 'Aux Site', 'OS Version']]
df2[['Hostname', 'Aux Site']] = df2[['Hostname', 'Aux Site']].replace({'*': ''}, regex=True)
df2.to_csv('new_survey_list-1', index=False)

df1[(df1['OS Version'].str.contains(MATCH_PATT,  na=False)) & (~df1['Aux Site'].str.contains('VCAD'))] [['Hostname', 'IP Address', 'Aux Site', 'OS Version']]

Hostname Aux Site OS Version
vlfox01 VCAD    CentOS 5.5
vlfox02 VCAD    RHEL 7.1
vlfox03 VCAD    RHEL 6.8
vlbrk01 brackn  RHEL 5.8
vlbrk02 brackn  SunOS 5.9
vlbrk03 brackn  RHEL 5.5
vlbrk04 brackn  RHEL 6.3
vlbrk05 brackn  RHEL  5.5

vlbrk01 brackn  RHEL 5.8
vlbrk02 brackn  SunOS 5.9
vlbrk03 brackn  RHEL 5.5
vlbrk04 brackn  RHEL 6.3
vlbrk05 brackn  RHEL  5.5