Python with open file error

Question

my python program gets via ssh a mail log data. When I try to go over it line per line with

with text as f:
    for line in f:
        try:
             .... regex stuff....

I get the error:

Traceback (most recent call last):
  File "xxxxxxxxxxxxxxxxxxxxxxxx", line 90, in <module>
    start()
  File "xxxxxxxxxxxxxxxxxxxxxxxx", line 64, in start
    with text as f:
AttributeError: __exit__

That doesn't work, the only solution which works for me is the following. When I save the text as file and open it again. But the file is about 1.24 MB big, which slows the program unnecessarely. Anyone know how I can get rid of the extra saving?

....
stdin, stdout, stderr = ssh.exec_command('sudo cat /var/log/mailing.log')
text = ''.join(stdout.readlines())
text_file = open('mail.log', 'w')
text_file.write(text)
text_file.close()
ssh.close()

with open('mail.log') as f:
    for line in f:
        try:
             .... regex stuff....

text is a not a context manager, why do you try to treat it as such? What is text in your original code? — Martijn Pieters
– Martijn Pieters, Commented Oct 17, 2013 at 10:40
the var 'text' is all the text in the file 'mailing.log'. I think I didn't understand the concept of a context manager.... 'ssh.exec_command()' comes from the module paramiko I use. — gulden
– gulden, Commented Oct 17, 2013 at 10:46

Niek de Klein · Accepted Answer · 2013-10-17 10:49:01Z

1

text is a string with data. You can't open that. Instead of opening it you should just loop over it

for line in text.splitlines(): 
    try:
         .... regex stuff....

answered Oct 17, 2013 at 10:49

Niek de Klein

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2 Comments

Martijn Pieters Over a year ago

Take a look at str.splitlines() too.

Niek de Klein Over a year ago

@MartijnPieters Didn't know splitlines(), I usually use split(os.sep). I changed it now. Thanks!

Bill Gribble · Accepted Answer · 2013-10-17 10:49:13Z

1

You probably want to look at StringIO from the standard library, which makes a string look more or less like a file.

Or, you could just say

for line in f.split('\n'):
     try:
        <regex stuff>

answered Oct 17, 2013 at 10:49

Bill Gribble

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