python - Writes, Deletes, but won't read text file -

i started learning python today. simple script either read, write 1 line to, or delete text file. writes , deletes fine, when choosing 'r' (read) option error:

ioerror: [errno 9] bad file descriptor

what missing here...?

from sys import argv  script, filename = argv  target = open(filename, 'w')  option = raw_input('what do? (r/d/w)')  if option == 'r':        print(target.read())  if option == 'd':     target.truncate()     target.close()    if option == 'w':     print('input new content')     content = raw_input('>')     target.write(content)     target.close()   

you've opened file in write mode, can't perform read on it. , secondly 'w' automatically truncates file, truncate operation useless. can use r+ mode here:

target = open(filename, 'r+') 

'r+' opens file both reading , writing

use with statement while opening file, automatically closes file you:

option = raw_input('what do? (r/d/w)')   open(filename, "r+")  target:     if option == 'r':         print(target.read())      elif option == 'd':         target.truncate()      elif option == 'w':         print('input new content')         content = raw_input('>')         target.write(content) 

as @abarnert has suggested it'll better open file per mode entered user, because read files may raise error 'r+' mode in first place:

option = raw_input('what do? (r/d/w)')  if option == 'r':     open(filename,option) target:         print(target.read())  elif option == 'd':     #for read files use exception handling catch errors     open(filename,'w') target:         pass  elif option == 'w':     #for read files use exception handling catch errors     print('input new content')     content = raw_input('>')     open(filename,option) target:         target.write(content)