Problem working with subprocess.check_call

Thu Oct 29 06:06:24 EDT 2015

On 29/10/15 16:52, David Aldrich wrote:
>> Hi
>> I am working on Linux with Python 3.4.
>> I want to do a bash diff on two text files and show just the first 20 
> lines of diff’s output. So I tried:
>> >>> cmd = 'head -20 <(diff ' + file1 + ' ' + file2 + ')'
>> >>> subprocess.check_call(cmd, shell=True)
>
You could use a shell pipe in your command - and use str.format() too 
for better readability, perhaps:
 > cmd = 'diff {} {} | head -20'.format( file1, file2 )
 > subprocess.check_call(cmd, shell=True)
Although this approach would not be recommended if file1 or file2 are 
not sanitised
pd
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