read() or readline() clobbers my variable

vincent wehren vincent at
Fri Jul 30 10:37:12 CEST 2004

washu wrote:

> Hi,
> This may be a simple problem but I can't seem to find a way around it. 
> I've pasted my code snippet below:
> import os
> input = os.popen("echo hello")
> input.readline()
> input.readline()
> The first input.readline() gives the output.  

You just read one line from a file open for reading.
Then you try to read the next line, and there is no next line.

> I even tried setting it equal to another variable (temp = input) but it
> seems like temp receives a pointer that just points to input. 
> temp.readline() produces the same results.
> I'd like to basically freeze the contents of input for further
> manipulation or comparison.  Any ideas?

Exactly: the *contents*.

 >>> import os
 >>> infile = os.popen("echo hello world")
 >>> infile
<open file 'echo hello world', mode 'r' at 0x00A8E560>
 >>> contents =
 >>> contents
'hello world\n'
 >>> # now do to contents whatever you want

Vincent Wehren

More information about the Python-list mailing list