첫번째나 두번째 줄을 파일명으로

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
 
import subprocess
 
bf = "1.txt"
f = open(bf, "r")
lines = f.readlines()
 
af1 = lines[0].strip() + ".txt"
af2 = lines[1].strip() + ".txt"
 
if af1 == '':
    subprocess.call("mv {0} {1}".format(bf, af2), shell=True)
else:
    subprocess.call("mv {0} {1}".format(bf, af1), shell=True)
 
f.close()

for old in *.txt; do
  # 첫번째/두번째줄에서 알파벳이나 숫자가 포함된 첫줄을 추출
  new=`head -2 "$old" | grep [[:alnum:]] | head -1`
  if [ "$new" == "" ]; then
    echo "$old: no alphanumeric characters in line 1 ~ 2"
  else
    echo "$old -> ${new}.txt"
    mv "$old" "${new}.txt"
  fi
done