Mac OS X Command Line Tools Tips

No. File type/creator info is stored in the metadata that HFS/HFS+ (file systems) support, along with lock/unlock status, the flag that says whether there's a custom icon, date/time created/modified, etc.

This attribute along with resource fork are both lost when transfering to other OS. When using OS X's command line tools, whether these data are kept depends on which command line tools you are using. Also, each version of OS X, Apple updates some command line tools so that they preserve these data.

Use “/Developer/Tools/GetFileInfo”. e.g. /Developer/Tools/GetFileInfo -c file.jpg. This tool is avaible on the Developers tools CD that came with Mac OS X at least 10.1 up to 10.4. Type man GetFileInfo to see its doc.

Use the tool /Developer/Tools/SetFile. You need to install the Developers tools CD that came with OS X at least 10.1. Type man SetFile to see its doc.

Use the “ls -l” command with “/rsrc” suffixed to the file name. For example, if “27.png” is your file, and you want to know if it has resource fork, do ls -l 27.png/rsrc. If the reported file size is 0, then it has no resource fork. Here's a commmand line log as a example:

$ ls -l 27.png 
-rwxrwxrwx    1 xah      staff     3184339 Jun 26  2001 27.png
$ 
$ ls -l 27.png/rsrc
-rwxrwxrwx    1 xah      staff       87410 Jun 26  2001 27.png/rsrc

No. (unless you append your file name with “/rsrc”, it will then get the size of just the resource fork.)

You can overwrite it with a empty file. Suppose “27.png” is a file with resource fork, and “tempf” is a empty file (size 0 bytes). Then do: cp tempf 27.png/rsrc will delete the resource fork. (to create a empty file, you can do: touch tempf)

Using “/bin/rm” is probably doing the right thing. To be safe, one can delete the resource fork first than rm the file. Example: touch emptyfile && cp emptyfile babe.jpg/rsrc && rm babe.jpg emptyfile.

The one in parenthesis is the actual file size (counting the resource fork). The one not in paren is the disk space it occupies, and the M and K abbreviations are multiples of 1024. The size returned by ls command does not include resource fork.

alice.jpg is a file with resource fork.
alice2.jpg is a file without resource fork.

                      Finder                ls
alice.jpg     |    584 KB, 595041     |    484995
alice2.jpg    |    476 KB, 484995     |    484995

In Finder, right click on a file a pull a menu «Create Archive of “my folder”», which will create a zip file but with meta data preserved. The command line equivalent is this: ditto -ck --sequesterRsrc --keepParent myFolder myFolder.zip.

The above pulls resource forks and HFS meta-data into a subdirectory “__MACOSX__”. You may just want to use this instead: ditto -ck --rsrc --keepParent myFolder myFolder.zip. See “man ditto” for detail.

In Finder, double click on a file. The command line equivalent is ditto -xk myFolder.zip myFolder.

As of Mac OS X 10.4.9, No. The command line tools at “/usr/bin/zip” and “/usr/bin/unzip” do not understand Mac meta data.

Using command line zip will simply create a archive without Mac metadata. Using unzip to unzip a zipped folder that has Mac metadata, will create a extraneous directory “__MACOSX__” or extraneous files with names prefixed by “.”.

As of Mac OS X 10.5, Mark Reed wrote me that the man page for both zip and unzip claims to understand mac metadata, but only unzip actually do.

No. (as of Mac OS X 10.4.9, mid 2007)

Yes. download this file: macosx_metadata_test.zip. After download, do not use “/usr/bin/unzip” to decompress it, because that would lose the meta data. Use instead this: ditto -xk macosx_metadata_test.zip macosx_metadata_test.

To create one, use hdiutil, e.g. hdiutil create -megabytes 1 ~/Desktop/afolder/ (this does not work with latest OS X... Read man hdiutil)

For Mac OS X 10.4.11 (as of 2007-12-17), to mount, do “hdid mydisk.dmg”. If it is encrypted, a password GUI dialog will pop up.

To mount a encrypted dmg file without having it popup a GUI dialog, do hdid -stdinpass mydisk.dmg. The volume should show up at “/Volumes/”.

To eject, first find out what disk device it is associated to by typing “df”. Here's a sample output:

/dev/disk1s2             31420     27428      3992  88% /Volumes/financial

then, use hdiutil to eject it: e.g. hdiutil detach /dev/disk2s2 Note: if one uses udiutil unmount /Volumes/financialto unmount it, it leaves a hdid process uncleared, creating problem when one tries to mount the dmg file again with error about 'financial' already in use.

Type sudo /usr/bin/sshd. One may need to generate a passphrase if this is run for the first time. Simply go to System Prefences, Sharing, and check mark Remote Login, will automatically generate the passphrase.

Type sudo smbd restart or sudo nmbd restart.

Use “open”. e.g. open /Applications/iTunes.app. Note that the “open” command behaves as if doubling clicking on finder. In particular, if a application is already running, it will just switch to it, not launch a new process. See “man open” for more detail.

Sometimes, you want to launch a separate process of Carbon Emacs or Aquamacs, and want to pass it command line arguments. You can do like this: nohup /Applications/Emacs.app/Contents/MacOS/Emacs -q &.

Note, however, Terminal has a feature such that if you close the window, it'll quit all command launched from it, even if you have used “nohub”. The “nohub” will only prevent the app from quitting if you exit the shell by “Ctrl+d”.

open -a safari myUrlStr. This will open the url in a currently running Safari browser if one has been launched. To specify other browsers, use “firefox” or “icab” for example.

Use applescript, like this: osascript -e 'tell application "System Events" to sleep'

/System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine &. You can make a bash shell alias, like this: “alias ssaver="...";” and put in “~/.bash_profile”.

You can also run the screen saver on your Desktop's background. Give the command the “-background” argument.

/usr/sbin/screencapture. Do “man screencapture” for detail.