$ git init
Initialized empty Git repository in /tmp/world_domination/.git/

$ git commit --message 'git init' --allow-empty
[master (root-commit) a9e1e55] git init

$ cat > README
README-driven development ftw!
^D

$ git add README
$ git commit --message 'I think this is the beginning of a beautiful README'
[master cabba9e] I think this is the beginning of a beautiful README
1 file changed, 1 insertion(+)
create mode 100644 README

$ cat > plans.rb
puts 'Hello, world domination!'
^D

$ git add plans.rb
$ git commit --message 'first working code!'
[master c0def00] first working code!
1 file changed, 1 insertion(+)
create mode 100644 plans.rb

$ git log --oneline --decorate
c0def00 (HEAD, master) first working code!
cabba9e I think this is the beginning of a beautiful README
a9e1e55 git init

$ tr a-z A-Z < README | sponge README
$ cat README
README-DRIVEN DEVELOPMENT FTW!

$ git add README
$ git commit --message 'fixup! cabba9e'
[master 5eaf00d] fixup! cabba9e
1 file changed, 1 insertion(+), 1 deletion(-)

$ git log --decorate --oneline
5eaf00d (HEAD, master) fixup! cabba9e
c0def00 first working code!
cabba9e I think this is the beginning of a beautiful README
a9e1e55 git init

$ git rebase --interactive --autosquash cabba9e^
pick cabba9e I think this is the beginning of a beautiful README
fixup 5eaf00d fixup! cabba9ea1fa1fabaff1edba99a9eba11ad5faded
pick c0def00 first working code!

[detached HEAD badf00d] I think this is the beginning of a beautiful README
1 file changed, 1 insertion(+)
create mode 100644 README
Successfully rebased and updated refs/heads/master.

$ git log --oneline --decorate
bea91e5 (HEAD, master) first working code!
badf00d I think this is the beginning of a beautiful README
a9e1e55 git init

$ cat > .rvmrc
rvm use 1.9.3@world_domination
^D

$ git add .rvmrc
$ git commit --message 'we’re getting serious now'
[master c0ffee5] we’re getting serious now
1 file changed, 1 insertion(+)
create mode 100644 .rvmrc

$ cat >> .rvmrc
bundle
^D

$ git status --short --branch
​## master
M .rvmrc

$ git update-index --assume-unchanged .rvmrc
$ git status --short --branch
​## master

$ git checkout -b pinky
Switched to a new branch 'pinky'

$ cat > plans.rb
if ENV['USER'] == 'brain'
  puts 'Hello, world domination!'
else
  puts 'Nice try. You must be Pinky.'
end
^D

$ git diff
diff --git a/plans.rb b/plans.rb
index beefbad..feedba9 100644
--- a/plans.rb
+++ b/plans.rb
@@ -1 +1,5 @@
-puts 'Hello, world domination!'
+if ENV['USER'] == 'brain'
+  puts 'Hello, world domination!'
+else
+  puts 'Nice try. You must be Pinky.'
+end

$ git diff --ignore-all-space
diff --git a/plans.rb b/plans.rb
index beefbad..feedba9 100644
--- a/plans.rb
+++ b/plans.rb
@@ -1 +1,5 @@
+if ENV['USER'] == 'brain'
  puts 'Hello, world domination!'
+else
+  puts 'Nice try. You must be Pinky.'
+end

$ git add plans.rb
$ git commit --message 'Pinky-proofing'
[pinky defaced] Pinky-proofing
1 file changed, 5 insertions(+), 1 deletion(-)

$ git checkout -
Switched to branch 'master'

$ git checkout -
Switched to branch 'pinky'

$ psql rupy
psql (9.2.1)
Type "help" for help.

# CREATE TYPE track AS ENUM ('1', '2', 'both');
CREATE TYPE

# CREATE TABLE agenda (                      \
    track track DEFAULT 'both',              \
    speaker text, title text, abstract text, \
    time tstzrange NOT NULL,                 \
    tags text[]                              \
  );
CREATE TABLE

# INSERT INTO agenda (title, time) VALUES                 \
  ('Registration', '[2012-11-17 8:45, 2012-11-17 9:30)');
INSERT 0 1

# SELECT track, title, time FROM agenda;
 track |    title     |                        time
-------+--------------+-----------------------------------------------------
 both  | Registration | ["2012-11-17 08:45:00+01","2012-11-17 09:30:00+01")
(1 row)

# INSERT INTO agenda (speaker, title, time) VALUES                   \
  ('Zed A. Shaw', 'Keynote', '[2012-11-17 9:30, 2012-11-17 10:15)');
INSERT 0 1

# INSERT INTO agenda (track, speaker, title, abstract, time, tags) VALUES \
  ('1', 'José Valim', 'Elixir', 'In this talk, José Valim will cover…',   \
  '[2012-11-17 10:15, 2012-11-17 10:45)', '{"Elixir", "Erlang"}');
INSERT 0 1

# INSERT INTO agenda (track, speaker, title, abstract, time, tags) VALUES \
  ('2', 'Honza Král', 'Extendable Django Apps', 'I will describe how…',   \
  '[2012-11-17 10:15, 2012-11-17 10:45)', '{"Django", "Python"}');
INSERT 0 1

# SELECT track, speaker, title, tags FROM agenda;
 track |     speaker     |           title           |          tags
-------+-----------------+---------------------------+------------------------
 both  |                 | Registration              |
 both  | Zed A. Shaw     | Keynote                   |
 1     | José Valim      | Elixir                    | {Elixir,Erlang}
 2     | Honza Král      | Extendable Django Apps    | {Django,Python}
(4 rows)

# SELECT track, title, to_char(lower(time), 'HH:MI') AS start, tags FROM agenda;
 track |           title           | start |          tags
-------+---------------------------+-------+------------------------
 both  | Registration              | 08:45 |
 both  | Keynote                   | 09:30 |
 1     | Elixir                    | 10:15 | {Elixir,Erlang}
 2     | Extendable Django Apps    | 10:15 | {Django,Python}
 both  | Break                     | 10:45 |
 1     | AngularJS                 | 11:00 | {AngularJS,JavaScript}
 2     | JS – from good to great   | 11:00 | {JavaScript}
 1     | The Future of Deployment  | 11:30 |
 2     | Rust from Python and Ruby | 11:30 | {Python,Ruby,Erlang}
(9 rows)

# SELECT track, speaker, title, to_char(lower(time), 'HH:MI') AS start, tags \
  FROM agenda WHERE time @> '2012-11-17 10:20'::timestamptz;
 track |  speaker   |         title          | start |      tags
-------+------------+------------------------+-------+-----------------
 1     | José Valim | Elixir                 | 10:15 | {Elixir,Erlang}
 2     | Honza Král | Extendable Django Apps | 10:15 | {Django,Python}
(2 rows)

# SELECT track, speaker, title, to_char(lower(time), 'HH:MI') AS start, tags \
  FROM agenda WHERE 'Erlang' = ANY(tags) OR 'JavaScript' = ANY(tags);
 track |    speaker     |           title           | start |          tags
-------+----------------+---------------------------+-------+------------------------
 1     | José Valim     | Elixir                    | 10:15 | {Elixir,Erlang}
 1     | Igor Minár     | AngularJS                 | 11:00 | {AngularJS,JavaScript}
 2     | Olov Lassus    | JS – from good to great   | 11:00 | {JavaScript}
 2     | Armin Ronacher | Rust from Python and Ruby | 11:30 | {Python,Ruby,Erlang}
(4 rows)

# SELECT abstract, abstract::tsvector, to_tsvector('english', abstract) \
  FROM agenda WHERE abstract IS NOT NULL;
         abstract         |         abstract          |         to_tsvector
--------------------------+---------------------------+-----------------------------
 In this talk, José Valim…| 'Elixir' 'In' 'José'…     | 'also':16 'behind':24…
 I… the challenges and…   | 'I' 'all'… 'challenges'…  | 'base':18 'challeng':22…
 What if you could write… | 'As' 'HTML' 'JavaScript.'…| 'app':8 'code':14 'could':4…
 Is it possible to make…  | 'Is' 'JavaScript' 'Let’s'…| 'care':20 'easier':10…
 Rust… wants to rival C++…| 'C++' 'Erlang,' 'Haskell'…| 'bit':23 'c':10 'design':31…
(5 rows)

# SELECT track, speaker, title, lower(time) AS start FROM agenda \
  WHERE abstract::tsvector @@ 'Haskell & Ruby'::tsquery;
 track |    speaker     |           title           |         start
-------+----------------+---------------------------+------------------------
 2     | Armin Ronacher | Rust from Python and Ruby | 2012-11-17 11:30:00+01
(1 row)

# SELECT track, speaker, title, lower(time) AS start FROM agenda         \
  WHERE to_tsvector('english', abstract) @@ to_tsquery('challenging:*');
 track |  speaker   |         title          |         start
-------+------------+------------------------+------------------------
 2     | Honza Král | Extendable Django Apps | 2012-11-17 10:15:00+01
(1 row)

$ find app/models -name '*.rb'
app/models/foo.rb
app/models/bar.rb
app/models/baz.rb
…

$ find app/models -name '*.rb' | xargs wc -l
    43 app/models/foo.rb
     2 app/models/bar.rb
    83 app/models/baz.rb
…

$ find app/models -name '*.rb' | xargs wc -l | sort -nr
 17124 total
  3663 app/models/qux.rb
  1426 app/models/quux.rb
  1240 app/models/corge.rb
   953 app/models/grault.rb
…                             # via Sam Livingston-Gray

$ git log --oneline --name-only
badf00d some commit message
app/models/foo.rb
cafeb01 another commit message
app/controllers/bars_controller.rb
app/views/users/_baz.html.erb
…
$ git log --oneline --name-only | grep '^[^ ]*\.rb$'
app/models/foo.rb
app/controllers/bars_controller.rb
app/views/users/_baz.html.erb
…
$ git log --oneline --name-only | grep '^[^ ]*\.rb$' | sort | uniq -c
      4 app/controllers/quxs_controller.rb
    183 app/controllers/quuxs_controller.rb
     63 app/controllers/corges_controller.rb
…
$ git log --oneline --name-only | grep '^[^ ]*\.rb$' | sort | uniq -c | sort -nr
   1096 app/models/foo.rb
    325 app/controllers/foos_controller.rb
    257 app/models/bar.rb
    251 config/routes.rb
    248 app/controllers/baz_controller.rb
    224 db/schema.rb
…                                         # via Samson Ootoovak/Michael Feathers

$ head mig.log
==  AddFooToBar: migrating ===========================
-- add_column(:bars, :foo, :integer)
  -> 0.1044s
-- add_column(:bars, :baz, :integer)
  -> 0.1144s
…
$ grep ' -> [0-9.]*s' mig.log
   -> 0.1044s
   -> 0.1144s
…
$ grep ' -> [0-9.]*s' mig.log | cut -d' ' -f5
0.1044s
0.1144s
…
$ grep ' -> [0-9.]*s' mig.log | cut -d' ' -f5 | tr -d s
0.1044
0.1144
…
$ grep ' -> [0-9.]*s' mig.log | cut -d' ' -f5 | tr -d s | xargs
0.1044 0.1144 …
$ grep ' -> [0-9.]*s' mig.log | cut -d' ' -f5 | tr -d s | xargs | tr ' ' +
0.1044+0.1144+…
$ grep ' -> [0-9.]*s' mig.log | cut -d' ' -f5 | tr -d s | xargs | tr ' ' + | bc
4.0230

$ cat db_name.sql | pv | psql db_name
97MB 0:00:12 [28.3MB/s] [        <=>                                               ]
^C

$ pv db_name.sql | psql db_name
97MB 0:00:12 [28.3MB/s] [============>                             ] 32% ETA 0:00:24
^C

$ pg_dump db_name | pv -s 600m | gzip > db_name.sql.gz
592MB 0:05:09 [1.92MB/s] [=======================================> ] 98%

$ pbpaste | pygmentize -l ruby -f rtf -O style=presentation | pbcopy
* pastes the system clipboard to the command line
* colours it: Ruby syntax, RTF format and presentation-style output
* copies it back to the system clipboard
                                   # via Katrina Owen/Gary Bernhardt

$ diff <(grep -r foo some_dir) <(grep -r foo other_dir)