[Tutor] Add newline's, wrap, a long string

[Martin Walsh]

David wrote:
> vince spicer wrote:
>> first, grabbing output from an external command try:
>>
>> import commands
>>
>> USE = commands.getoutput('grep USE /tmp/comprookie2000/emege_info.txt
>> |head -n1|cut -d\\"-f2')
>>  
>> then you can wrap strings,
>>
>> import textwrap
>>
>> Lines = textwrap.wrap(USE, 80) # return a list
>>
>> so in short:
>>
>> import commands, textwrap
>> data = textwrap.wrap(commands.getoutput('my command'), 80)
>>
>>
>>
>> Vince
> Thanks Vince,
> I could not get command to work, but I did not try very hard;
> ["cut: the delimiter must be a single character Try `cut --help' for
> more", 'information. head: write error: Broken pipe']

Ah, I see. This error is most likely due to the typo (missing space
before -f2).

> 
> But textwrap did the trick, here is what I came up with;
> 
> #!/usr/bin/python
> 
> import subprocess
> import os
> import textwrap
> import string
> 
> def subopen():
>     u_e = subprocess.Popen(
>         'grep USE /tmp/comprookie2000/emerge_info.txt |head -n1|cut
> -d\\" -f2',
>         shell=True, stdout=subprocess.PIPE,)
>     os.waitpid(u_e.pid, 0)
>     USE = u_e.stdout.read().strip()
>     L = textwrap.wrap(USE, 80) # return a list
>     Lines = string.join(L, '\n')

Just one more comment, string.join is deprecated, yet join is a method
of str objects. So ...

      Lines = '\n'.join(L)

... or use textwrap.fill which returns a string with the newlines
already in place ...

      Lines = textwrap.fill(USE, 80)

HTH,
Marty

>     fname = 'usetest.txt'
>     fobj = open(fname, 'w')
>     fobj.write(Lines)
>     fobj.close
> 
> subopen()
> 
> Here is the output;
> http://linuxcrazy.pastebin.com/m66105e3
>