For me, the fastest way to open iCal while I'm in the shell is to run "ical" from the prompt, which launches the app.

My ~/bin/ical program is simply

#!/bin/sh
open /Applications/iCal.app/

and my ~/bin/addr is

#!/bin/sh
open "/Applications/Address Book.app/"

You might think that it's overkill to write a shell program for such a silly task, but it's all about optimizing my time at the keyboard for my common cases.

Someone will note that I could have used a shell alias, and that's true, too. Either way, I want a super simple way to get the apps I use most often.

Display all 2224 possibilities? (y or n)

Because it went and compiled a list of EVERY executable you could possibly want to execute?

Yeah, me, too, and I hate it. The fix is simple. Add this to your ~/.bashrc

shopt -s no_empty_cmd_completion

No more completion on nothing!

I played with ssh-agent, but that seemed to require starting up a process every time I logged in, and I couldn't get it running in my .bashrc, and it required manually adding keys.

And then I stumbled across this article that introduced me to the IdentityFile argument. Now I have this in my ~/.ssh/config and all is well with the world.

Host github.com
    HostName github.com
    IdentityFile ~/.ssh/github_rsa
    User petdance

Just reading the article about the "old way" to do what surround.vim does was informative, showing me vim tricks I didn't know.

Seriously, anyone who reads Mechanix should have Peteris' blog in her syndication reader.

Last night, an incredible number of people showed up to Code-N-Splode to hear about Git.

I was not at all prepared for that number of people, but grateful that a couple experts were on hand to help - Sarah Sharp, Audrey Eschright and Michael Schwern (and others) all contributed to the discussion. Thanks for all the great questions! I'm looking forward to Sarah’s advanced tutorial next month.

Selena Deckelmann leads the Portland PostgreSQL Users Group and regularly contributes to Code-N-Splode, a group dedicated to getting more women involved in open source. She likes Perl. She'll be running a code sprint and giving a lightning talk on having more fun with open source at PostgreSQL Conference West, on October 17-19, 2008.

Subscribe to Peteris' blog. It's well worth reading.

All I need to do is match across the contents of /usr/share/dict/words in a Perl one-liner. The -n flag means "loop over the input file, but don't print $_". My little program goes in -e, and it looks like this:

$ perl -lne'print if /t/ && /o/ && /l/ && /k/ && /i/ &&
    /e/ && /n/' /usr/share/dict/words 
allokinetic
ankylopoietic
anticlockwise
automatonlike
bibliokleptomania
....

Lots of good words, but they're awfully long. Let's limit it to seven-letter bingos. We have to use the -l flag to drop the linefeed from the input lines, so the length call is accurate.

$ perl -lne'print if /t/ && /o/ && /l/ && /k/ && /i/ &&
    /e/ && /n/ && length($_)==7' /usr/share/dict/words
$

Shoot, nothing there. Let's try eight.

perl -lne'print if /t/ && /o/ && /l/ && /k/ && /i/ &&
    /e/ && /n/ && length($_)==8' /usr/share/dict/words 
knotlike
townlike

"knotlike"! That would have been beautiful. Oh well. :-(

What seems to happen is that at first we just want to add--oh say for example JUST ONE, SINGLE LITTLE -v flag. Well, that's so easy enough to hand-hack, that of course we do so... But just like any other piece of software, these things all seem to have a way of overgrowing their original expectations... Getopt::Long is just *wonderful*, up--I believe--to any job you can come up with for it. Too often its absence means that I've in the long run made more work for myself--or others--by not having used it originally. [Emphasis mine -- Andy]

I can't agree more. I don't care if you use Getopt::Long or Getopt::Declare or Getopt::Lucid or any of the other variants out there. You know know know that you're going to add more arguments down the road, so why not start out right?

Yes, it can be tricky to get through all of its magic if you're unfamiliar with it, but it's pretty obvious when you see enough examples. Take a look at prove or ack for examples. mech-dump is pretty decent as an example as well:

GetOptions(
    'user=s'        => \$user,
    'password=s'    => \$pass,
    forms           => sub { push( @actions, \&dump_forms ); },
    links           => sub { push( @actions, \&dump_links ); },
    images          => sub { push( @actions, \&dump_images ); },
    all             => sub { push( @actions, \&dump_forms, \&dump_links, \&dump_images ); },
    absolute        => \$absolute,
    'agent=s'       => \$agent,
    'agent-alias=s' => \$agent_alias,
    help            => sub { pod2usage(1); },
) or pod2usage(2);

Where the value in the hashref is a variable reference, the value gets stored in there. Where it's a sub, that sub gets executed with the arguments passed in. That's the basics, and you don't have to worry about anything else. Your user can pass --abs instead of --absolute if it's unambiguous. You can have mandatory flags, as in agent=s, where --agent must take a string. On and on, it's probably got the functionality you need.

One crucial reminder: You must check the return code of GetOptions. Otherwise, your program will carry on. If someone gives your program an invalid argument on the command-line, then you know that the program cannot possibly be running in the way the user intended. Your program must stop immediately.

Not checking the return of GetOptions is as bad as not checking the return of open. In fact, I think I smell a new Perl Critic policy....

What's the value of pi? If you're wondering how much edging to put around a circular flower bed, then "3" is probably good enough. If you're in school, then maybe "22/7" is a good approximation. If you're in NASA, then maybe 12 decimal places will do.

For someone wanting to see an overview of how either Mason or Class::DBI work with real-world examples, not just samples from documentation, this is a great place to start.

# Find all the .pm files in @INC
my @files = File::Find::Rule->file
                            ->name( '*.pm' )
                            ->in( @INC );

What this search REALLY says is "Find every single file in all these trees, then do an slow IO stat call to the operating system on every single one to work out which ones are files, and only then do a quick regex match on the file names to keep the 5% that have the ending we want and throw away the 95% that don't".

Now I'm worried about if I'm doing the right order of checking in File::Next, a lightweight file finder that ack relies on.

CREATE OR REPLACE FUNCTION exacttitle_key( TEXT ) 
    RETURNS text AS $$
    DECLARE
        key TEXT := upper( $1 );

    BEGIN
        key = regexp_replace( key,
            '^ *(?:A|AN|EL|LA|LO|THE|LOS|LAS)\\M *', '' );
        key = regexp_replace( key, '[^0-9A-Z ]+', '', 'g' );
        key = regexp_replace( key, ' {2,}', ' ', 'g' );

        RETURN trim( key );
    END

$$ LANGUAGE 'plpgsql'
IMMUTABLE STRICT;

and tested it out, and all looked well. It was marked as IMMUTABLE, so Pg can use it as an index function. I created the index in psql:

create index testbook_exacttitle on testbook 
    using btree (exacttitle_key(title));

And all was well. Now I wanted to see how long it took to create that index, so from the shell I did:

$ time psql -c'drop index testbook_exacttitle; \
    create index testbook_exacttitle  on testbook \
    using btree (exacttitle_key(title));'

I knew it would take about 5 minutes to add this index on 6.7 million records in testbook, so I didn't expect it to come back right away. Then I realized that site response fell off the table. ptop showed a couple dozen SELECT queries waiting to run. I killed the process that was running the CREATE INDEX. All the pending queries went on their merry way. Everything was back to normal.

I tried that command line again, and the results were identical. Dozens of queries backed up until I killed the CREATE INDEX process. But why were those queries backing up? That index was not used by any code yet. I asked in #postgresql, but nobody knew the answer. Then, someone said a word that clicked in my head. I made a little change to how I was running the commands, and everything worked just fine.

What was the word that helped Encyclopedia Lester figure out the problem? Turn to page 47 for the answer.

The word was "transaction". If there are multiple commands as part of the -c option to psql, they are executed in in one transaction. DROP INDEX blocks on the entire table, so the entire transaction blocked. When I ran the DROP INDEX separately, and then reran the CREATE INDEX by itself, there was only the long blocking on the new index, which did not yet exist.

(With apologies to Donald J. Sobol and Encyclopedia Brown)

history|awk '{a[$2]++} END{for(i in a){ \
printf "%5d\t%s \n",a[i],i}}'|sort -rn|head

That works, of course, but who wants to use awk and the shell? I pulled out the old Data::Hash::Totals module I wrote a while back, along with Perl's built-in awk simulation:

$ history | perl -MData::Hash::Totals -ane'$x{$F[1]}++;' \
-e'END{print as_table(\%x, comma => 1)}' | head
207 vim
143 svn
125 make
 90 ack
 77 cd
 45 sdvx
 34 ssq
 31 ls
 25 ./login-fixup
 19 tail

alester:~ : cat `which sdvx`
#!/bin/sh

svn diff -x -w $* | view -