WHAT is [0] in subprocess.Popen(blah).communicate()[0]

[johnny]

Can someone tell me what is the reason "[0]" appears after
".communicate()"

For example:
last_line=subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()[0]

Thank you.

 

[Fredrik Lundh]

Can someone tell me what is the reason "[0]" appears after
".communicate()"

For example:
last_line=subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()[0]

as explained in the documentation, communication() returns two values,
as a tuple. [0] is used to pick only the first one.

see the Python tutorial for more on indexing and slicing.

</F>

 

[Neil Cerutti]

Can someone tell me what is the reason "[0]" appears after
".communicate()"

For example:
last_line=subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()[0]

as explained in the documentation, communication() returns two
values, as a tuple. [0] is used to pick only the first one.

see the Python tutorial for more on indexing and slicing.

I like using pattern matching in these simple cases:

last_line, _ = subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()

 

[Gabriel Genellina]

I like using pattern matching in these simple cases:

last_line, _ = subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()

pattern matching???


--
Gabriel Genellina
Softlab SRL

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Espacio para todos tus mensajes, antivirus y antispam ¡gratis!
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[Fredrik Lundh]

Gabriel Genellina wrote:

I like using pattern matching in these simple cases:

last_line, _ = subprocess.Popen([r"tail","-n 1", "x.txt"],
stdout=subprocess.PIPE).communicate()

pattern matching???

http://www.haskell.org/tutorial/patterns.html

(the syntax's called "target lists" in Python)

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