Mac OS X Panther for Unix Geeks, Second Edition

Using the Terminal

The first order of business when exploring a new flavor of Unix is to find the command prompt. In Mac OS X, you won’t find the command prompt in the Dock or on a Finder menu. The Terminal application is instead located in the /Applications/Utilities directory. Don’t open it just yet, though. First, drag the Terminal’s application icon to the Dock so you’ll have quick access to it when you need to use the Terminal. To launch the Terminal, click its icon in the Dock once, or double-click on its icon in the Finder view.

Tip

The full path to the Terminal is /Applications/Utilities/Terminal.app, although the Finder hides the .app extension. Terminal.app is not a binary file. Instead, it’s a Mac OS X package , which contains a collection of files, including the binary and support files. You can Control-click (or right-click) on the Terminal in the Finder and select Show Package Contents to see what’s inside. You can alternatively use the standard UNIX commands ls and cd to explore the directory /Applications/Utilities/Terminal.app/.

After the Terminal starts, you’ll be greeted by the banner message from /etc/motd and a bash prompt, as shown in Figure 1-1.

Figure 1-1. The Terminal window

Launching Terminals

One difference xterm users will notice is that there is no obvious way to launch a new Terminal window from the command line. For example, the Mac OS X Terminal has no equivalent to the following commands:

xterm &
xterm -e -fg green -bg black -e pine -name pine -title pine &

Instead, you can create a new Terminal window by typing

-N or selecting File → New Shell from the menu bar.

Tip

To cycle between open Terminals, you can use the same keystroke that most other Mac OS X applications use,

-`. You can also switch between open Terminals by pressing

-Right Arrow or

-Left Arrow, using the Window menu, or by Control-clicking on the Terminal’s Dock icon to reveal a context menu of open Terminals. You can also jump to a particular Terminal window with

-number (see the Window menu for a list of numbers).

You can customize startup options for new Terminal windows by creating .term and .command files.

.term files

You can launch a customized Terminal window from the command line by saving some prototypical Terminal settings to a .term file, then using the open command to launch the .term file (see Section 1.7, later in this chapter). You should save the .term file someplace where you can find it later: if you save it in ~/Library/Application Support/Terminal, the .term file shows up in Terminal’s File → Library menu.

To create a .term file, open a new Terminal window, and then open the Inspector (File → Show Info, or

-I) and set the desired attributes, such as window size, fonts, and colors. When the Terminal’s attributes have been set, save the Terminal session (File → Save, or

-S) to a .term file, say named proto.term. If you save this file to ~/Library/Application Support/Terminal, you’ll be able to launch a new Terminal window with the proto. term file’s special attributes from the File → Library menu.

Alternatively, you can launch such a Terminal window from the command line, by issuing the following command (depending on where you saved proto.term):

open ~/Library/Application\ Support/Terminal/proto.term   
open ~/Documents/proto.term

Tip

You can also double-click on proto.term in the Finder to launch a Terminal window.

The .term file is an XML property list (plist) that you can edit with a text editor like vim (it can be invoked with vi, which is a symbolic link to vim) or with the Property List Editor application (/Developer/Applications/Utilities).^[1] By default, opening the .term file creates a new Terminal window. You can configure the window so it executes a command by adding an execution string to the .term file. When you launch the Terminal, this string is echoed to standard output before it is executed. Example 1-1 shows an execution string that connects to a remote host via ssh and exits when you log out.

Example 1-1. An execution string to connect to a remote host

<key>ExecutionString</key>
<string>ssh xyzzy.oreilly.com; exit</string>

.command files

Adding the .command extension to any executable shell script will turn it into a double-clickable executable. The effect is similar to that of a .term file, except that you can’t control the Terminal’s characteristics in the same way. (A .command file will use the default Terminal settings.) However, you can stuff the shell script full of osascript commands to set the Terminal characteristics after it launches. The osascript utility lets you run AppleScript from the command line.^[2] Example 1-2 is a shell script that sets the size and title of the Terminal, and then launches the pico editor.

Example 1-2. Launching the pico editor

#!/bin/sh 
# Script RunPico.command
osascript  <<EOF
tell app "Terminal"
  set number of rows of first window to 34
  set number of columns of first window to 96
  set custom title of first window to "PICO Editor"
end tell
EOF
pico $@

If you don’t want to give the shell a .command extension, you could also use the Finder’s Get Info option (File → Get Info, or

-I) to choose which application will open the executable. To do this, perform the following steps:

1. Highlight the script’s icon in the Finder.

2. Choose Get Info from the File menu (

   

   -I).

3. In the Get Info dialog, choose Open with:.

4. Click the drop-down menu and choose Other.

5. In the Choose Other Application dialog, select All Applications rather than Recommended Applications.

6. Find and choose the Terminal (/Applications/Utilities) application.

7. Click Add.

8. Close the Get Info window (

   

   -W).

You can assign a custom-made icon to your shell scripts, and place them in the right section of the Dock. You can also drag the executable’s icon to the lower section of the Places sidebar in the left column of the Finder, although this section of the Finder is intended primarily for quick access to frequently visited folders. To change an icon, use the following procedure:

1. Copy the desired icon to the clipboard.

2. Select your script in the Finder and open the Get Info window (

   

   -I). The file’s icon appears in the upper-left corner.

3. Click the current icon, and use the Paste option (Edit → Paste, or

   

   -V) to paste the new icon over it.

4. Close the Get Info window (

   

   -W) to save the icon to the application.

To add the shell script application to the Dock, locate the application in the Finder and drag its icon to the Dock. Now you can click on the script’s Dock icon to invoke the script.

Split Screen Terminal Feature

You can split a Terminal window into upper and lower sections by clicking on the small broken rectangle located just above the Terminal’s scroll bar. The upper window contains the buffer (i.e., what you would see if you scrolled up in a non-split window), while the lower window contains your current Terminal section. This feature is useful for example, if you need to edit a file and copy and paste output from earlier in the Terminal session. Figure 1-2 shows a split Terminal window.

Figure 1-2. The Terminal’s split screen

Contextual Menu

Users familiar with the X Window System know that right-clicking an xterm window opens a terminal-related contextual menu. Mac OS X’s Terminal also has a contextual menu that can be accessed by Control-clicking (or right-clicking if you have a two- or three-button mouse). The Terminal contextual menu includes the choices: Copy, Paste, Paste Selection, Select All, Clear Scrollback, Send Break (equivalent to Control-C), Send Hard Reset, Send Reset, and Window Setting. Each of these items has keyboard shortcuts.

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^[1] For more information on XML, see Learning XML (O’Reilly) or XML in a Nutshell (O’Reilly).

^[2] To learn more about AppleScript, see AppleScript: The Definitive Guide (O’Reilly; 2004).