Skip to main content

Talk: Python Tools, the UNIX Philosophy, and sort Tricks

Updated link.

I recently gave a talk at BayPiggies called Python Tools, the UNIX Philosophy, and sort Tricks. Thanks go to Glen Jarvis for recording it. The "slides" are below:
This is a random collection of topics related to Python tools.

Talk about the UNIX philosophy:
Small tools.
My problems tend to be too large for RAM, but not too big for one machine.
UNIX and batch processing are a natural fit.
Multiple processes = multiple CPUs.
Multiple programming languages = more flexibility.
Pipes = concurrency without the pain.
Scales linearly and predictably, unlike databases.
UNIX tools that already exist are helpful and fast.

Use the optparse module to provide consistent command line APIs:
Here's an example of the setup from the docs:
: from optparse import OptionParser
: parser = OptionParser()
: parser.add_option("-f", "--file", dest="filename",
: help="write report to FILE", metavar="FILE")
: parser.add_option("-q", "--quiet",
: action="store_false", dest="verbose", default=True,
: help="don't print status messages to stdout")
: (options, args) = parser.parse_args()
Here's an example of my own help text
: Usage: [options]
: Options:
: -h, --help show this help message and exit
: --assert-head=FIELD1\tFIELD2\t...
: assert that the first line of the file matches this
: --delete-head delete the first line of input
: -n NUM, --num-fields=NUM
: assert that there are this many fields per line
: --drop-blank-lines delete blank lines instead of raising an error

sort -S 20% -T /mnt/some_other_drive ...

You need a consistent format.
Most UNIX tools don't understand true TSV, but only an approximation thereof:
My own code raises an exception in cases where it would actually matter.
Many UNIX tools are ignorant of encoding issues:
Sometimes playing dumb works and sometimes it hurts.
Using the csv module:
: import csv
: DEFAULT_KARGS = dict(dialect='excel-tab', lineterminator='\n')
: def create_default_reader(iterable):
: """Return a csv.reader with our default options."""
: return csv.reader(iterable, **DEFAULT_KARGS)
: ...
Using mysqlimport.
: mysqlimport \
: --user=$MYSQL_USERNAME \
: --password=$MYSQL_PASSWORD \
: --columns=id,name \
: --fields-optionally-enclosed-by='"' \
: --fields-terminated-by='\t' \
: --fields-escaped-by='' \
: --lines-terminated-by='\n' \
: --local \
: --lock-tables \
: --replace \
: --verbose \
: $DATABASE ${BUILD}/sometable.tsv
To see warnings:

Show pdb in the context of a web app:
: import pdb
: from pprint import pprint
: pdb.set_trace()
: pprint(request.environ)


Oinopion said…
The link doesn't work :(
jjinux said…
Thanks for the heads up. I'll see what's up.
jjinux said…
Ok, the link has been fixed. Thanks again.

Popular posts from this blog

Ubuntu 20.04 on a 2015 15" MacBook Pro

I decided to give Ubuntu 20.04 a try on my 2015 15" MacBook Pro. I didn't actually install it; I just live booted from a USB thumb drive which was enough to try out everything I wanted. In summary, it's not perfect, and issues with my camera would prevent me from switching, but given the right hardware, I think it's a really viable option. The first thing I wanted to try was what would happen if I plugged in a non-HiDPI screen given that my laptop has a HiDPI screen. Without sub-pixel scaling, whatever scale rate I picked for one screen would apply to the other. However, once I turned on sub-pixel scaling, I was able to pick different scale rates for the internal and external displays. That looked ok. I tried plugging in and unplugging multiple times, and it didn't crash. I doubt it'd work with my Thunderbolt display at work, but it worked fine for my HDMI displays at home. I even plugged it into my TV, and it stuck to the 100% scaling I picked for the othe

ERNOS: Erlang Networked Operating System

I've been reading Dreaming in Code lately, and I really like it. If you're not a dreamer, you may safely skip the rest of this post ;) In Chapter 10, "Engineers and Artists", Alan Kay, John Backus, and Jaron Lanier really got me thinking. I've also been thinking a lot about Minix 3 , Erlang , and the original Lisp machine . The ideas are beginning to synthesize into something cohesive--more than just the sum of their parts. Now, I'm sure that many of these ideas have already been envisioned within , LLVM , Microsoft's Singularity project, or in some other place that I haven't managed to discover or fully read, but I'm going to blog them anyway. Rather than wax philosophical, let me just dump out some ideas: Start with Minix 3. It's a new microkernel, and it's meant for real use, unlike the original Minix. "This new OS is extremely small, with the part that runs in kernel mode under 4000 lines of executable code.&quo

Haskell or Erlang?

I've coded in both Erlang and Haskell. Erlang is practical, efficient, and useful. It's got a wonderful niche in the distributed world, and it has some real success stories such as CouchDB and Haskell is elegant and beautiful. It's been successful in various programming language competitions. I have some experience in both, but I'm thinking it's time to really commit to learning one of them on a professional level. They both have good books out now, and it's probably time I read one of those books cover to cover. My question is which? Back in 2000, Perl had established a real niche for systems administration, CGI, and text processing. The syntax wasn't exactly beautiful (unless you're into that sort of thing), but it was popular and mature. Python hadn't really become popular, nor did it really have a strong niche (at least as far as I could see). I went with Python because of its elegance, but since then, I've coded both p