Write list of list to CSV?

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After running this from my original file which Im working, It's not writing any data on the CSV, maybe u have encountered/ any idea with this?

I am not sure I understand this

There no data after running the script. no trace or anything will running. It's just no data can be seen once you open the csv file.

Posting my config. maybe you can see something unusual. Thanks

import re, base64, os, sys, subprocess, csv, itertools

with open('list.txt') as csvfile:
    rilist = csv.reader(csvfile, delimiter=',')
        
#Put the data from excel here
    rtrlist = []
    intlist = []
    ilist =[]
    dlist = []
    blist = []
        
#Action - Put the data from excel to variable[list]
    for col in rilist:
        rtr = col[0]
        intf = col[1]

        rtrlist.append(rtr)
        intlist.append(intf)
##    csvfile.close()
##    print(rtrlist,"\n",intlist)

    #Change Directory
    os.chdir("/rs/configs")
    print("pwd=%s" % os.getcwd())

    ## START OF THE LOOP ##
    for a,b in zip(rtrlist, intlist):
        srtr = a.strip()
        sint = b.strip()
        subint = re.sub("\d+\/*", "", sint)
        print ("Processing.... ",srtr,sint)
        proc = subprocess.Popen(("grep", "-A11", "interface %s"%sint, srtr), stdout = subprocess.PIPE)  
        lbl = proc.communicate()[0]
        teststr = lbl.decode()
        print (teststr)
        
        #SEARCH INTERFACES
        ipat = re.findall(r"(?P<intrfname>%s+\d+\/.*)" %subint, teststr)
        ilist.append(ipat)
        print ("List of Interface: \n",ipat)

        #SEARCH INTERFACE DESCRIPTION
        dpat = re.findall("(?<=description\s)([A-Za-z0-9]+\;.*)", teststr)
##        dpat = ','.join(ddpat)
        dlist.append(dpat)
        print ("\nDescription: ",dpat)

        #GET BUNDLE ID / CHANNEL GROUP
        bbpat = re.findall("(?<=bundle id\s)+\d+", teststr)
        bpat = ','.join(bbpat)
        blist.append(bpat)
        print ("\nBundled: ",bpat)

print ("\nRTR List: ",rtrlist)
print ("\nINT List: ",ilist)
print ("\nDESC List: ",dlist)
print ("\nBUN List: ",blist)

rtrlist = [[ele] for ele in rtrlist]
dlist = [[ele] for ele in dlist]

## EXPORT AS CSV
with open('intlist.csv', 'w', newline='') as updatecsv:
    write = csv.writer(updatecsv, delimiter=',',lineterminator='\n')
    for cols in zip(rtrlist,ilist,dlist):
        rows = itertools.zip_longest(*cols, fillvalue='')
        write.writerows(rows)
updatecsv.close()
print ("\n Done...csv file has been updated")