bash-style pipes in python?
Dan Stromberg - Datallegro
dstromberg at datallegro.com
Thu Jul 12 02:56:21 CEST 2007
I'm constantly flipping back and forth between bash and python.
Sometimes, I'll start a program in one, and end up recoding in the
other, or including a bunch of python inside my bash scripts, or snippets
of bash in my python.
But what if python had more of the power of bash-style pipes? I might not
need to flip back and forth so much. I could code almost entirely in python.
The kind of thing I do over and over in bash looks like:
# exit on errors, like python. Exit on undefind variables, like python.
# give the true/false value of the last false command in a pipeline
# not the true/false value of the lat command in the pipeline - like
# nothing I've seen
set -o pipefail
# save output in "output", but only echo it to the screen if the command fails
if ! output=$(foo | bar 2>&1)
echo "$0: foo | bar failed" 1>&2
echo "$output" 1>&2
Sometimes I use $PIPESTATUS too, but not that much.
I'm aware that python has a variety of pipe handling support in its
But is there a similarly-simple way already, in python, of hooking the stdout of
process foo to the stdin of process bar, saving the stdout and errors from both
in a variable, and still having convenient access to process exit values?
Would it be possible to overload | (pipe) in python to have the same behavior as in
I could deal with slightly more cumbersome syntax, like:
(stdout, stderrs, exit_status) = proc('foo') | proc('bar')
...if the basic semantics were there.
How about it? Has someone already done this?
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