All The Quickies

• Backups on the cheap (Unix->General)
  I've been using hfstar for doing backups. I tar directory hierarchies to an external firewire drive from my TiBook (say my entire $HOME directory, plus the /Applications directory. There's probably other stuff that should be snarfed (like /Library), but I didn't on my last backup, and doing a restore from scratch seemed to work OK. Here's a quick outline of backing up to the external firewire drive called "Wikkit":
  • % sudo mkdir /Volumes/Wikkit/backup
  • % cd /Users
  • % sudo hfstar cf - bork | (cd /Volumes/Wikkit/backup; sudo hfstar xf -)
  The tar above is the standard push-pull tar. Both sides are run as root so that owner, group, and permissions are preserved for the files.

  To Restore:

  • % cd /Users
  • % sudo mv bork bork-orig
  • % cd /Volumes/Wikkit/backup
  • % sudo hfstar cf - bork | (cd /Users; sudo hfstar xf -)

  Some folks have had success with psync, but we haven't used it yet.

• cd to directory with a space in its name (Unix->General)
  There's two ways to do it. The first is to backslash-escape the spaces:
  % cd /Users/bork/development/cool stuff/neat things

  The other is to use shell completion to put in the backslashes for you. In the above path, if you type
  % cd /Users/bork/development/cool[tab], it'll expand "cool stuff" for you.

• Changing all *.oop files to *.ack (Unix->General)
  % ~/bin/rename.pl 's/.oop$/.ack/' *.oop

  To tack on an extension to all files, do something like % ~/bin/rename.pl 's/(.*)/$1.jpg/' *

• Converting from DOS to unix line terminators (Unix->General)
  % perl -pi -e 's/ / /g' mealcsv.csv

• Dealing with directories with spaces in them (Unix->General)
  You can either escape the directory name with a space: % cd /Users/bork/Library/Screen Savers

  or you can surround it with quotes: % cd "/Users/bork/Library/Screen Savers"

  Note that tilde expansion (~/Library) is suppressed if you use the quotes.

• Directory space consumption (Unix->General)
  To see how much disk space a directory consumes, use
  % du -sk dir_name

  To see how much each of a directory's contents consume, use
  % du -sk dir_name/* | sort -n to get a list ordered by size.

• Doing something to a hierarchy of files (Unix->General)
  To do something to all of the html files in a directory (e.g. to grep something)
  % cd directory
% find . -name "*.h" -exec grep NSDoWhatIMean {} ; -print
  Don't forget the dot right after find, and the {} construct. Also make sure there's a space after the {} and ;

• Finding suid executables (Unix->General)
  To find setuid executables, run

  % find . -type f -perm +06000 -print

  (or use find / to start looking from the root directory.

• Getting a count from grep (Unix->General)
  To see how many times "fix me" occurs in the Objective-C files in the current directory:
  % grep -c "fix me" *.m

• Getting curl to download a file (Unix->General)
  % curl -O http://borkware.com/quickies/files/fullscreensaver.tar.gz

• Getting grep to return file names of matches rather than the actual match (Unix->General)
  Use the -l (dash ell) flag to grep. If a file contains the expression, the name of the file (rather than the matching line) is displayed. e.g. to open all the files that contain 'rzolf'

  % grep -l rzolf *.ham | xargs open

• Removing files with a leading "-" (Unix->General)
  % rm -- -i-am-a-bad-file

• Replacing a string in a set of files (Unix->General)
  % perl -pi.bak -e 's/OLDSTRING/NEWSTRING/g' *.html
  This will leave "*.bak" files around of the original version, in case the replacement string didn't quite do what you wanted.

• Restricting Find to only deal with files (not directories) (Unix->General)
  % find . -type f -name "*.html" -exec grep Spoon {} ; -print

• Running a pipeline in sudo (Unix->General)
  % sudo sh -c "tar cf - * | (cd /mirror4/web; tar xf -)"

• safely copying directories (Unix->General)
  cp -R is generally unsafe to copy directories with since it will copy through symbolic links rather than just copying the link (newer cp's have an -H flag that will work around this). The classic unix way of doing things like this is a push-pull tar:

  % tar cf - dir-name | (cd /destination-dir; tar xf -)

  In English: tar out through a pipe into a subshell that's changed directories, feeding that pipe into the tar extraction. If you run both sides of the pipeline as root (via sudo), the file owners and permissions will be preserved (which cp won't do)

• Seeing all the flags gcc takes (Unix->General)
  % gcc -v --help

• Seeing the console.log without running Console.app (Unix->General)
  In a terminal or an emacs shell:
  % tail -f /var/tmp/console.log

• Seeing the parent process id in ps (Unix->General)
  Use the ppid option with the -o flag:

  % ps -axo user,pid,ppid,vsz,tt,state,start,time,command

• Using "find" with multiple -name clauses (Unix->General)
  % find . ( -name "*.jpg" -o -name "*.gif" ) -exec do_something_wih {} ;

• Using ImageMagick to get the dimensions of a file (Unix->General)
  % identify filename.jpg

  If you want to be studly, you can use -format to tailor the output

  % identify -format "insert into bw_graphics values (generate_primary_key(), '/images/llamas/%f', %w, %h);" *.jpg
  generates a sql insert statement for each image.

• Using Image Magick to scale an image proportionally (Unix->General)
  % find . -name "*.jpg" -exec convert -verbose -geometry 150x150 {} {} ;
  This converts the files in-place, so have a backup. Even though the geometry is specified as 150x150, that just means make the image no larger than 150 in either direction.

• using ssh (or CVS) without a password (Unix->General)
  Suppose you have two machines, the local one (your laptop) and the remote one (the honking big server located in Minneapolis that hosts gitdown.com) To ssh (or CVS) from the laptop to the server without needing a password, perform these steps:
  1. % ssh-keygen -t rsa
     (don't use a passphrase. Just hit return twice)

  2. % scp ~/.ssh/id_rsa.pub gitdown.com:

  3. On the remote machine (gitdown)
     

     % mv ~/id_rsa.pub ~/.ssh/authorized_keys

• I can't move or symlink a directory (Unix->Hacks)
  If you get the error

  mv: rename build/ to oopack: Is a directory
  

  when using mv or ln on the command line, that's a Darwin error. To correct the problem, remove the trailing slash from the directory name.

• Creating a RAM Disk (Unix->Random)
  % hdid ram://size where size is the size in bytes. the system will round that number up or down as it sees fit.

• Setting file system attribute flags (Unix->Random)
  chflags in Mac OS X works like chattr over in Linux-land. So to make a file immutable (can't change it, even if you're the superuser), you can sudo chflags uchg file-name(s). To undo it, do sudo chflags nouchg file-name(s)

• Adding a new machine alias via netinfo(e) (Unix->Administration)
  The NetInfo Manager utility is painfully slow. Here's how to add a machine via the command line. In this case adding the IP for a machine called "tower" (thanks to rzolf)

  # niutil -create . /machines/tower
  # niutil -createprop . /machines/tower ip_address 10.0.1.155
  # niutil niutil -createprop . /machines/tower serves ./local
  

• Increasing shared memory limits (Unix->Administration)
  Edit /System/Library/StartupItems/SystemTuning/SystemTuning

  tweak some values, like

  sysctl -w kern.sysv.shmmax=167772160 # bytes: 160 megs
  sysctl -w kern.sysv.shmmin=1
  sysctl -w kern.sysv.shmmni=32
  sysctl -w kern.sysv.shmseg=8
  sysctl -w kern.sysv.shmall=65536 # 4k pages: 256 megs
  

  Save, and restart your system.

• wrong kind of tag compiler error. (Tools->Random)
  This one stumped me for awhile:
  BWNagType.h:23: `BWConcreteType' defined as wrong kind of tag

  In this particular case, I had a type I had declared with:
  @class BWConcreteType; and later on I had decided to turn it into an enum:
  typedef enum BWConcreteType { ... } BWConcreteType;
  without removing the previous @class declaration. So be on the look out for conflicting types for the same symbol.

• Building projects from the command line (Project Builder->General)
  Look at pbxbuild. We've got a rant about cocoa development in emacs, which includes a discussion of pbxbuild.

• Changing the default Project Builder projects (Project Builder->General)
  Don't like something about the default project that Project Builder gives you? Go to /Developer/ProjectBuilder Extras/Project Templates/ and edit the projects there. The changes will take effect next time you create a new project.

• How do I add a new folder to my Files view? (Project Builder->General)
  Select the folder you want the new folder to be a child of. Select Project->New Group. Give it a name. Note that the hierarchy of files in Project Builder is a fantasy of the project, and doesn't necessarily reflect what's actually in the file system.

• Treat warnings as errors (Project Builder->General)
  To treat all warnings as errors, open the Targets tab, double-click the target, go to the "Build Settings" tab, scroll down to Build Settings, look for WARNING_CFLAGS. Edit that, and add -Werror to what's already there.

• Using Objective C++ (Project Builder->General)
  name your source file blah.M (upper case M), or name your source file blah.mm (two lower case Ms)

• Loading a nib file (General->General)
  

  if ([NSBundle loadNibNamed: @"theNibName.nib"  owner: self]) {
      ... life is happy
  } else {
      ... couldn't load the nib
  }
  

• Verifying Localizable.strings (General->General)
  if there's an error in Localizable.string, your NSLocalizedString() call will not look up the strings in the file. To verify the file, do something like this:

  % pl < Localizable.strings

• Enabling core files (Debugging->General)
  Core files are handy to have around if your program crashes with a SEGV, bus error, or if it raises an abort(). You can dig into the core file with gdb There are two ways to enable core files:
  • in your C shell do
    % limit coredumpsize unlimited
    (you can put this into your .cshrc. I don't know what to do for bash)

  • Or in your program do
    struct rlimit corelimit = { RLIM_INFINITY, RLIM_INFINITY };
setrlimit (RLIMIT_CORE, &corelimit); You may need to also add
    #include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>

  Core files seem to be getting dumped into /cores, rather than the directory the program was run from.

• NSDebug.h (Debugging->General)
  Take a look at /System/Library/Frameworks/Foundation.framework/Headers/NSDebug.h. Lots of low-level unsupported APIs for mucking around with gory technical details.

• Breaking on "Deallocation of a pointer not malloced" messages (Debugging->gdb)
  Put a breakpoint on fprintf

• Get a stack trace of all threads (Debugging->gdb)
  (gdb) thread apply all where

• Setting a breakpoint before shared libraries are loaded (Debugging->gdb)
  Need to set a breakpoint, say on a Cocoa library function, or something in a shared library you're loading later? Set a "future breakpoint":
  (gdb) fb -[NSTextView drawRect:]

• Ignoring signals (gdb->General)
  (gdb) handle SIGTRAP nostop

  The signal still goes to your program. Another handy option is 'ignore' to prevent it coming to the program. Also there is 'print' to print a message go on.

• Seeing functions and selectors (gdb->General)
  info selectors will show you all of the selectors in the application's symbol table. info funcitons will show you all of the functions. You can supply regular expressions to limit the output.

• Disabling control-Z from backgrounding emacs (emacs->General)
  I find emacs' control-Z behavior to be pretty annoying (it backgrounds the program if you're in a shell, or hides the window if you're in X). Add this to your .emacs file:
  (global-set-key "C-Z" nil)

• Fixing emacs C mode indenting (emacs->General)
  Here's a way to change the C indenting style to a major style, and override some of the pre-set values (like how emacs 21 changed the bsd indent level from 4 to 8. Gee thanks guys):

  (setq c-default-style "bsd"
        c-basic-offset 4)

• Fixing "no job control in this shell" (emacs->General)
  Emacs in Mac OS X 10.1.3 (and other versions) has an annoying habit of having broken shells when you do M-x shell. You get an error like "Inappropriate ioctl for device, no job control in this shell", which makes interrupting or backgrounding programs in shell mode impossible. Domo-kun gave me a one-line patch to the emacs source:
  #define DONT_REOPEN_PTY
  . Add that to darwin.h and build emacs. You can get the emacs source from the Darwin projects page. If you'd like a binary, drop us some mail.

• Resetting shell mode's idea of the current working directory (emacs->General)
  Sometimes the shell mode will get confused as to what the current working directory is (like if you use aliases to move to a new directory, or if you use the conveniences like !$). M-x dirs will tell the shell buffer to figure out what the current working directory is.

• Revisiting / reloading a file in emacs (emacs->General)
  The $Id: $ tags for CVS are nice, but it can be a pain when you're doing lots of checkins and have to re-load the file each time. You can either execute M-x revert-bufer or bind that to a key, or else use a trick by doing C-x C-v which invokes find-alternate-file, but just so happens to have the current buffer name, so you just have to do C-x C-v RET

• Scroll line with cursor to the top of the window (emacs->General)
  C-U 0 C-L

  (you can put in another number besides zero to scroll the line with the cursor to that particular line in the buffer)

• Showing current column position (emacs->General)
  M-x column-number-mode

• Toggling read-only mode in a buffer (emacs->General)
  C-X C-Q

• Turning off command highlighting in shell mode (emacs->General)
  Emacs 21, which comes with Mac OS X 10.2, "helpfully" puts into bold the commands you execute in the shell. This drives me nuts, so I figured out how to turn it off. Add this to your .emacs file:

  (setq comint-highlight-input nil)

• Turning off incremental-search highlighting (emacs->General)
  Emacs 21, which comes with Mac OS X 10.2, has highlighting enabled when doing incremental search (which drives me nuts). You can turn that off by setting this in your .emacs file:

  (setq search-highlight nil)

  You may also need to
  (setq isearch-lazy-highlight nil)

  To turn off underlining of matching results. Only some OS X installs need this setting.

• Undo within a given region (emacs->General)
  C-U C-_

• Use only spaces when indenting code (emacs->General)
  (setq indent-tabs-mode nil)

• Using carriage returns in query-replace / replace-string (emacs->General)
  Use C-Q C-J (control-Q control-J) each time you want to include a carriage return. e.g. to double-space everything

  M-x replace-string RET C-Q C-J RET C-Q C-J C-Q C-J RET

  Or to put "bloogie " at the beginning of every line

  M-x replace-string RET C-Q C-J RET C-Q C-J b l o o g i e SPACE RET

• Help! My Sheet won't go away (NSWindow->General)
  You may need to call [sheet close] in addition to your [NSApp endSheet: sheet returnCode:23]

• Making a floating palette (NSWindow->General)
  To make a floating palette with small controls, make the palette an NSPanel, and n IB make it a "Utility Window".

• I want my window's background to be yellow (NSWindow->Hacks)
  Why you'd want to do that, I don't know, but someone asked me how to turn the window background yellow. Since the window has a contentView NSView in it, this adds a category on it that draws the background with a transparent yellow. You also get the pinstripe effects. Just put this code anywhere.

  @implementation NSView (BWYellowView)
  
  - (void) drawRect: (NSRect) rect
  {
      NSColor *transparentYellow;
  
      rect = [self bounds];
  
      transparentYellow = [NSColor colorWithCalibratedRed: 1.0
                                   green: 1.0
                                   blue: 0.0
                                   alpha: 0.333];
      [transparentYellow set];
      [NSBezierPath fillRect: rect];
  
  } // rect
  
  @end // BWYellowView
  

  I have no idea how you colorize the titlebar.

• Forwarding key events to another window (NSWindow->Random)
  To forward key events to another window, make subclass of NSWindowsendEvent:

  - (void) sendEvent: (NSEvent *) anEvent
  {
      if ([anEvent type] == NSKeyDown) {
          [someOtherWindow sendEvent: anEvent];
  
      } else {
          [super sendEvent: anEvent];
      }
  
  } // sendEvent
  

  It's up to you to figure out what "someOtherWindow" is, whether it's a delegate or an instance variable that holds the other window.

• Converting an event to view coordinates (NSView->General)
  NSPoint point = [self convertPoint: [event locationInWindow] fromView: nil];

• Becoming firstResponder if you don't have an editable cell (NSView->Hacks)
  You make a custom view, add it to your window in Interface Builder, and you make it the first responder. When you run the program, your custom view is not the first responder, instead some lame-O textfield has snagged keyboard focus. To address this, override this undocumented method:

  - (BOOL) _hasEditableCell
  {
      return (YES);
  } // _hasEditableCell
  

  This workaround is necessary at least for Mac OS X 10.1.*.

• Disabling Chimera's url completion pop-up (Random->General)
  Add this to your ~/Library/Application Support/Chimera/Profiles/default/xyz.slt/prefs.js file:

  user_pref("browser.urlbar.autocomplete.enabled", false);

• Easy NSLogging of basic data structures (Random->General)
  NSString has a couple of convenience functions for print out basic structures like NSRect and NSSize:
  • NSStringFromRect (someNSRect);
  • NSStringFromPoint (someNSPoint);
  • NSStringFromSize (someNSSize);

• minimal tool (Random->General)
  I got tired of looking for this everytime I make a simple one-off tool without using Project Builder:

  #import 
  int main (int argc, char *argv[])
  {
      NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
  
      [pool release];
  
  } // main
  

  And you can compile it on the command line with:

  cc -o test -framework Foundation file-name.m
  

• Putting an image on a disk image's window (Random->General)
  To have snazzy disk images that have your logo or picture of your dog appear when you open them, do this:
  • run disk copy, make a new blank image. I'm calling mine "thingie"
  • copy image file to the mounted fake drive (logo.jpg)
  • open fake drive, choose Show View Options. Make sure you're just changing the current window, and not Everything.
  • Choose "picture", select the logo.jpg that's on the thingie drive
  • resize your window as appropriate
  • run this in the terminal to hide the logo.jpg file
    /Developer/Tools/SetFile -a V /Volumes/thingie/logo.jpg
  • eject thingie and re-mount it
  • you should now see your image, and no visible picture file icon

• Reducing the size of a .dmg disk image (Random->General)
  DiskCopy won't let you create a disk image of less than 5 megabytes (a bit inconvenient for packaging a program that's 30K). Image->Convert Image will let you compress the image. As a side-effect, this makes the image read-only.

• Putting an imac to sleep at the login box (Random->Random)
  Press the power button.

• Finding my resources (Screen Savers->General)
  To find resources (say an image) from within the screensaver, use NSBundle bundleForClass. So, to get atomsymbol.jpg you would do something like

         NSBundle *bundle;
         NSString *path;
  
         bundle = [NSBundle bundleForClass: [self class]];
         path = [bundle pathForResource: @"atomsymbol"  ofType: @"jpg"];
         image = [[NSImage alloc] initWithContentsOfFile: path];

• How about a simple sample or two? (Screen Savers->General)
  There's SimpleSaver, a minimal 'bounce a line around the screen' screensaver. FullScreenSaver is the same thing, but it bounces the line around the user's desktop instead of just a black screen. Also check out Drip, a little more sophisticated (even has a configuration panel).

• How do I set the name that's displayed in the preference panel? (Screen Savers->General)
  The "Product Name" setting on the Project Builder target has that. Change it by:
  1. open the Targets pane in Project Builder
  2. double-click on your target
  3. go to the Build Settings tab
  4. Edit your Product Name under General Settings

• Where is my preference file? (Screen Savers->General)
  The screen saver preference file lives in the ~/Library/Preferences/ByHost directory. The name of the file is the name that you pass to defaultsForModuleWithName:, followed by .someBigNumber.plist.

  So, on my machine,

      userPrefs = [ScreenSaverDefaults defaultsForModuleWithName: @"BWDrip"];

  creates a file /Users/bork/Library/Preferences/ByHost/BWDrip.0003931024a6.plist

• Running a screensaver as your desktop background (Screen Savers->Random)
  In a terminal, run

  % /System/Library/Frameworks/ScreenSaver.framework/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine -background &

  (all one command)

• Basics (NSTimer->General)
  

  - (void) handleTimer: (NSTimer *) timer
  {
      do some work here...
  } // handleTimer
  
  NSTimer *timer;
  
  timer = [NSTimer scheduledTimerWithTimeInterval: 0.5
                   target: self
                   selector: @selector(handleTimer:)
                   userInfo: nil
                   repeats: YES];
  

• Populating a dictionary with predefined values (NSDictionary->General)
  dictinoaryWithObjectsAndKeys is handy if you're setting up a defaults preference dictionary (or text attributes, or any dictionary) by hand:

      defaults = [NSDictionary dictionaryWithObjectsAndKeys:
                               [NSNumber numberWithFloat: 25.0], @"density",
                               [NSNumber numberWithFloat: 40.0], @"rate",
                               nil];
  

• Changing a file to -kb after it's been added (CVS->General)
  % cvs admin -kb filename

• Checking .nib and .pbproj files into CVS (CVS->General)
  You'll need to use the cvswrappers file provided in the devtools. The easiest thing to do is to copy it to your homedir and prepend a dot:

  % cp /Developer/Tools/cvswrappers ~/.cvswrappers

  You can also add the contents of that fike to your repository.

  .pbproj files aren't handled by the cvswrappers by default. You'll need to add a line like this:

  *.pbproj -k 'b' -f '/Developer/Tools/cvs-unwrap %s' -t '/Developer/Tools/cvs-wrap %s %s' -m 'COPY'

• Dealing with the past (CVS->General)
  To check out the world as it was 3 days ago:

  % cvs checkout -D "3 days ago" blork

  Or via a date (month/day/year)

  % cvs checkout -D "10/17/2002" fnord

  or recently in time

  % cvs diff -D "1 hour ago" ook.blah

• Getting cvs update to build new directories (CVS->General)
  % cvs update -d [whatever]

• Showing the log comments between a set of revisions (CVS->General)
  % cvs log -r1.2:1.5 multiprocessing.txt

• Loading an image from a website (NSURL->General)
  (this will block until it loads)

      NSURL *url;
      NSData *data;
      NSImage *blork;
      url = [NSURL URLWithString: @"http://borkware.com/hacks/random-pic"];
      data = [url resourceDataUsingCache: NO];
      blork = [[NSImage alloc] initWithData: data];

• Loading a string from a website (NSURL->General)
  (this will block until it loads)

      NSURL *url;
      NSData *data;
      NSString *blork;
      url = [NSURL URLWithString: @"http://borkware.com/hacks/random"];
      data = [url resourceDataUsingCache: NO];
      blork = [[NSString alloc] initWithData: data  encoding: NSASCIIStringEncoding];

• Grabbing the bits from the screen (Graphics->General)
  (note doesn't grab from multiple monitors, and doesn't seem to grab Classic windows)

          NSWindow *grabWindow;
          NSView *grabbedContentView;
          NSBitmapImageRep *screenBits;
          NSRect mainScreenBounds;
          NSImage *screenImage;
  
          mainScreenBounds = [[NSScreen mainScreen] frame];
  
          grabWindow = [[NSWindow alloc] initWithContentRect: mainScreenBounds
                                         styleMask: NSBorderlessWindowMask
                                         backing: NSBackingStoreRetained
                                         defer: NO
                                         screen: nil];
  
          [grabWindow setAlphaValue: 0.0];
          [grabWindow setLevel: NSPopUpMenuWindowLevel];
          [grabWindow orderWindow: NSWindowAbove  relativeTo: 0];
  
          grabbedContentView = [grabWindow contentView];
          [grabbedContentView lockFocus];
          screenBits = [[NSBitmapImageRep alloc] initWithFocusedViewRect: mainScreenBounds];
          [grabbedContentView unlockFocus];
  
          screenImage = [[NSImage alloc] initWithSize: mainScreenBounds.size];
          [screenImage addRepresentation: screenBits];
          [grabWindow close];
  

• Handling double-clicks (NSTableView->General)
  Use NSTableView's -setDoubleAction: method, and supply it a standard IBAction-style method selector.

  You may need to also do -setTarget:. double-clicks get sent if the column isn't editable, so you may need to grab the column and do a -setEditable: NO on it.

• Add pgplsql support (Postgresql->General)
  % createlang plpgsql template1

• Backing up a database (Postgresql->General)
  % pg_dump databasename > db.out

• Connecting to a user / database (Postgresql->General)
  Say you have your primary database user as 'nsadmin', and they have a database called 'openacs'. If you're using the default pg_hba.conf, you can connect to the database, logged in as an ordinary person, by doing

  % psql -U nsadmin opeancs

• Creating a new database (Postgresql->General)
  % createdb database-name

• Creating a new user (Postgresql->General)
  psql=# create user bork with password 'bork';

  You can also do this for a passwordless user: % crateuser bork

• Inserting a time column (Postgresql->General)
  If you have the minutes, seconds, and am/pm and want to get them into a time column (time without timezone), you can do something like this:

  psql=# select to_timestamp('10:45am', 'HH12:MIam')::timetz::time;
   to_timestamp
  --------------
   10:45:00
  (1 row)
  

• Limiting selections to X number of rows (Postgresql->General)
  use the "limit" statement:

  select stuff from some_table
   where stuff.blah > 12
   limit 5
  

• Logging in as a specific user (Postgresql->General)
  % psql database-name user-name

• Logging into a remote database (Postgresql->General)
  On machine tower, dbname borkdb, user nettest
  % psql -h tower borkdb nettest

• Manually starting the database (Postgresql->General)
  % pg_ctl -D /usr/local/pgsql/data -l /tmp/pgsql.log start

• Restoring a Database (Postgresql->General)
  % psql -d databasename -f db.out

• Seeing available databases (Postgresql->General)
  % psql -l
  (lower case Ell)

• Selecting a random row from a table (Postgresql->General)
  use the random() function.

      select stuff.src, stuff.width, stuff.height from
          (select src, width, height,
                  random()
             from bw_eyes
            order by 4) stuff
      limit 1
  

  This selects a random row from bw_eyes and returns the interesting data from it. This query is used on the quickies pages to randomly select an image of eyes staring back.

• Time interval math to integer (Postgresql->General)
  If you take the difference between two timestamps, you can end up with an unweildly value like "00:06:14.37086 days old". You can cast the timestamps into just regular dates like:
  select current_timestamp()::date - entry_date::date as days_old from kb_nuggets;

• Increasing memory buffer sizes (Postgresql->Administration)
  If you try upping your shared_buffers in your postgresql.conf, and get an error similar to this:

  IpcMemoryCreate: shmget(key=5432001, size=266371072, 03600) failed: 
  Invalid argument
  This error usually means that PostgreSQL's request for a shared memory
  segment exceeded your kernel's SHMMAX parameter. 
  

  You should increase your the shmmax parameters using tips in the Unix administration quickies.

• Darwin Website (Darwin->General)
  Since I can never remember this, it's at developer.apple.com/darwin.

• Darwin's CVSROOT string (Darwin->CVS)
  for read-only checkouts:

  setenv CVSROOT :pserver:username@anoncvs.opensource.apple.com:/cvs/Darwin

• Appending to the end of a textview (NSTextView->General)
  

      NSRange range;
      range = NSMakeRange ([[textView string] length], 0);
  
      [textView replaceCharactersInRange: range withString: string];

• Deleting the selected text (NSTextView->General)
  [textView delete: nil]

• Forcing validation of pending text field entries (NSTextView->General)
  [window makeFirstResponder: window]

• Moving insertion point to the end (NSTextView->General)
  NSRange range = { [[textView string] length], 0 };
[textView setSelectedRange: range];

• Moving insertion point to the start (NSTextView->General)
  NSRange zeroRange = { 0, 0 };
[textView setSelectedRange: zeroRange];

• Restricting typed in text to just digits (NSTextView->General)
  Create a subclass of NSNumberFormatter, add this method, and hook up the formatter to your text fields.

  - (BOOL) isPartialStringValid: (NSString **) partialStringPtr
          proposedSelectedRange: (NSRangePointer) proposedSelRangePtr
                 originalString: (NSString *) origString
          originalSelectedRange: (NSRange) origSelRange
               errorDescription: (NSString **) error
  {
      NSCharacterSet *nonDigits;
      NSRange newStuff;
      NSString *newStuffString;
  
      nonDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
      newStuff = NSMakeRange(origSelRange.location,
                             proposedSelRangePtr->location
                             - origSelRange.location);
      newStuffString = [*partialStringPtr substringWithRange: newStuff];
  
      if ([newStuffString rangeOfCharacterFromSet: nonDigits
              options: NSLiteralSearch].location != NSNotFound) {
          *error = @"Input is not an integer";
          return (NO);
      } else {
          *error = nil;
          return (YES);
      }
  
  } // isPartialStringValid

• scrolling to the beginning of a textview (NSTextView->General)
  NSRange zeroRange = { 0, 0 };
[textView scrollRangeToVisible: zeroRange];

• Scrolling to the end of a textview (NSTextView->General)
  

      NSRange range;
      range = NSMakeRange ([[textView string] length], 0);
  
      [textView scrollRangeToVisible: range];

  I've heard that scrollRangeToVisible is O(N) for the length of the text. So be on the lookout if you have lots of text involved.

• Changing checkbox toggle state (NSControl->General)
  [myCheckbox setState: NSOffState]

  NSOnState also works.

• Converting string to an integer (NSString->General)
NSString *string = ...;
int value = [string intValue];

  Similarly, there is a floatValue and doubleValue NSString methods.

• NSLog without the extra crud (NSString->General)
  NSlog puts too much crud in front of the logging line. For a foundation tool that output stuff, it gets in the way. I'd still like for a replacement to expand %@, which the printf() family won't do. Here's a some code that'll do that.

  #include <stdarg.h>
  
  void LogIt (NSString *format, ...)
  {
      va_list args;
  
      va_start (args, format);
  
      NSString *string;
  
      string = [[NSString alloc] initWithFormat: format  arguments: args];
  
      va_end (args);
  
      printf ("%s\n", [string cString]);
  
      [string release];
  
  } // LogIt
  

• Substring matching (NSString->General)
  NSRange range = [[string name] rangeOfString: otherString options: NSCaseInsensitiveSearch];

• Getting a document's window (NSDocument->General)
  

  - (NSWindow *) window
  {
      NSArray *windowControllers;
      windowControllers = [self windowControllers];
  
      NSWindowController *controller;
      controller = [windowControllers objectAtIndex: 0];
  
      NSWindow *window;
      window = [controller window];
  
      return (window);
  
  } // window

• Keeping backup files of documents (NSDocument->General)
  override NSDocument's keepBackupFile:

  - (BOOL) keepBackupFile
  {
      return (YES);
  } // keepBackupFile
  

  This will do the tilde thing to the older version of the file.

• Enabling and Disabling menu items (NSMenu->General)
  Under most circumstances, it happens automatically: a menu item will be disabled if there is no object in the responder chain that handles the menu's action. If you want to override this behavior or extend it further, override validateMenuItem: and do something like this:

  - (BOOL) validateMenuItem: (id ) menuItem
  {
      int result = YES;
  
      if ([menuItem action] == @selector(deleteNote:)) {
          if ([notes count] == 1) {
              result = NO; // can't delete the last note
          }
  
      } else if ([menuItem action] == @selector(gotoNote:)) {
          if ([notes count] == 1) {
              result = NO; // can't go to a different not if only one
          }
      }
  
      return (result);
  
  } // validateMenuItem
  

• Running code before a menu action is sent (NSMenu->General)
  The NSMenuWillSendActionNotification is posted to the notification center before the action is invoked.

• Cheap profiling (Unix API->General)
  You can use gettimeofday() to get sub-second granularity for timing:

  #include <sys/time.h>
  struct timeval start, end;
  ...
  gettimeofday (&start, NULL);
  
  ... the code you're timing
  
  gettimeofday (&end, NULL);
  double fstart, fend;
  fstart = (start.tv_sec * 1000000.0 + start.tv_usec) / 1000000.0;
  fend = (end.tv_sec * 1000000.0 + end.tv_usec) / 1000000.0;
  NSLog (@"it took %f seconds", fend - fstart);
  

• Handling double-clicks in a browser (NSBrowser->General)
  

  - (void) awakeFromNib
  {
      [browser setTarget: self];
      [browser setDoubleAction: @selector(browserDoubleClick:)];
  } // awakeFromNib
  
  ...
  
  - (IBAction) browserDoubleClick: (id) sender
  {
      int column = [browser selectedColumn];
      int row = [browser selectedRowInColumn: column];
  
      // then dig into your data tructure with the row and column
  
  } // browserDoubleClick

• Moving a file to a tilde file (NSFIleManager->General)
  

      NSString *filename = @"/my/original/file/name";
      NSString *tildeFilename;
      tildeFilename = [NSString stringWithFormat: @"%@~", filename];
  
      // remove it first, otherwise the move will fail
      [defaultManager removeFileAtPath: tildeFilename
                      handler: nil];
  
      // now rename the file
      [defaultManager movePath: filename
                      toPath: tildeFilename
                      handler: nil];

• Reading a file as an NSData (NSFIleManager->General)
  

      NSString *filename = @"/this/is/my/file/path";
  
      NSFileManager *defaultManager;
      defaultManager = [NSFileManager defaultManager];
  
      NSData *data;
      data = [defaultManager contentsAtPath: filename];

• Removing a file (NSFIleManager->General)
  

      NSFileManager *defaultManager;
      defaultManager = [NSFileManager defaultManager];
  
      [defaultManager removeFileAtPath: tildeFilename
                      handler: nil];

  The handler is an object that will be sent message, like fileManager:shouldProceedAfterError: if something goes wrong during the removal.

• Saving an NSData to a file (NSFIleManager->General)
  

      NSString *filename = @"/this/is/my/file/name";
      NSData *data = // get NSData from somewhere, like NSPropertyListSerialization
  
      NSFileManager *defaultManager;
      defaultManager = [NSFileManager defaultManager];
  
      // either remove or rename the existing file using NSFileManager
  
      [defaultManager createFileAtPath: filename
                      contents: data
                      attributes: nil];

• Reading property lists from XML (XML->General)
  This will read property lists in XML (or any of the other property list formats:)

      NSData *data = // get NSData from somewhere, like NSFileManager
      if (data) {
          myRootObject = [NSPropertyListSerialization
                             propertyListFromData: data
                             mutabilityOption: NSPropertyListMutableContainers
                             format: nil
                             errorDescription: nil];
      }
  

  For the mutability options of the resulting object, you can also use NSPropertyListImmutable and NSPropertyListMutableContainersAndLeaves

• Saving property lists as XML (XML->General)
  You can save any of the "property list" classes (NSDictionary, NSArray,NSNumber, NSString, NSData) as XML like this:

      NSData *data;
      data = [NSPropertyListSerialization
                 dataFromPropertyList: notes
                 format: NSPropertyListXMLFormat_v1_0
                 errorDescription: nil];

  Then write out the data using NSFileManager, or whatever other mechanism you wish.

• Supporting decoding (NSCoder->General)
  

  - (id) initWithCoder: (NSCoder *) aDecoder
  {
      if (self = [super init]) {
          // or else [super initWithCoder: aDecoder] if your superclass
          // supports it.  NSObject does not.
  
          // decoding a C type
          [aDecoder decodeValueOfObjCType: @encode(int)
                    at: &itemCount];
  
          // decoding an array of C structs
          if (items != NULL) {
              free (items);
          }
          items = malloc (sizeof(BWRawPathItem) * itemCount);
  
          int i;
          for (i = 0; i < itemCount; i++) {
              [aDecoder decodeValueOfObjCType: @encode(BWRawPathItem)
                        at: &items[i]];
          }
  
          // decoding an object
          name = [aDecoder decodeObject];
          [name retain];
  
          // any other random initializations that don't come from
          // the encoder
          fooby = -1;
      }
      [self retain];
  
      return (self);
  
  } // initWithCoder

• Supporting encoding (NSCoder->General)
  

  - (void) encodeWithCoder: (NSCoder *) aCoder
  {
      // [super encodeWithCoder:] if you inherit from a class
      // that supports encoding.  NSObject does not.
  
      // encoding a C type
      [aCoder encodeValueOfObjCType: @encode(int)
              at: &itemCount];
  
      // encoding an array of C structs
      int i;
      for (i = 0; i < itemCount; i++) {
          [aCoder encodeValueOfObjCType: @encode(BWRawPathItem)
                  at: &items[i]];
      }
  
      // encoding an object
      [aCoder encodeObject: name];
  
  } // encodeWithCoder

• Launching a task (NSTask->General)
  Here are the basics to launch "ls -l -a -t" in the current directory, and then read the result into an NSString:

      NSTask *task;
      task = [[NSTask alloc] init];
      [task setLaunchPath: @"/bin/ls"];
  
      NSArray *arguments;
      arguments = [NSArray arrayWithObjects: @"-l", @"-a", @"-t", nil];
      [task setArguments: arguments];
  
      NSPipe *pipe;
      pipe = [NSPipe pipe];
      [task setStandardOutput: pipe];
  
      NSFileHandle *file;
      file = [pipe fileHandleForReading];
  
      [task launch];
  
      NSData *data;
      data = [file readDataToEndOfFile];
  
      NSString *string;
      string = [[NSString alloc] initWithData: data
                                 encoding: NSUTF8StringEncoding];
      NSLog (@"woop!  got\n%@", string);

  Of course, you can use different NSFileHandle methods for different styles of reading, and you can make a pipe for standard input so you can feed data to the task.

• Performing complex pipelines. (NSTask->Graphics)
  You can create multiple NSTasks and a bunch of NSPipes and hook them together, or you can use the "sh -c" trick to feed a shell a command, and let it parse it and set up all the IPC. This pipeline cats /usr/share/dict/words, finds all the words with 'ham' in them, reverses them, and shows you the last 5.

      NSTask *task;
      task = [[NSTask alloc] init];
      [task setLaunchPath: @"/bin/sh"];
  
      NSArray *arguments;
      arguments = [NSArray arrayWithObjects: @"-c",
                           @"cat /usr/share/dict/words | grep -i ham | rev | tail -5", nil];
      [task setArguments: arguments];
      // and then do all the other jazz for running an NSTask.

• Using sockets with cocoa (Samples->General)
  networkolizer.tar.gz is a very short sample that opens a socket connection (using the Berkeley sockets API), and then writes an HTTP request, and reads the response.

• Apple's recommended retain/release technique (NSObject->General)
  This way if "get" performance is important:

  - (NSString*) title
  {
      return (title);
  } // title
  
  - (void) setTitle: (NSString *) newTitle
  {
      [title autorelease];
      title = [newTitle copy];
  } // setTitle
  

  For maximum safety (this is thread safe too), use this:

  - (NSString *) title
  {
      return [[title retain] autorelease];
  } // title
  
  - (void) setTitle: (NSString *) newTitle
  {
      if (title != newtitle) {
          [title release];
          title = [newTitle copy];
      }
  } // setTitle
  

• Should you retain the delegate in your objects? (NSObject->General)
  If you're creating an object, and you provide a delegate feature, should you retain the delegate? Nope! These objects are peers, not an owner/owned, or parent/child relationship. If you free your object, you shouldn't need to worry about memory management of your delegate. Likewise, if someone releases the delegate object, they should clean up after themselves and tell you to have a nil delegate.

• My color well has a little triangle on it? (NSColorWell->General)
  If your color well has a little triangle in the corner after you set the color programatically, that probably means the NSColor you used was created in Device space (e.g. colorWithDeviceRed:green:blue:alpha:) If you use a Calibrated color (colorWithCalibratedRed:green:blue:alpha:), the triangle goes away.