Terminal
From Mac Guides
The default UNIX shell in Mac OS X Panther (10.3) or later is Bash
Contents |
Commands
Here is a list of common commands:
- ls
- list files and directories
- cd
- change directory
- mkdir
- create a new directory
- cp
- copy files or directories
- mv
- move (rename) files or directories
- rm
- remove files or directories
See the Terminal Commands category for a list of useful Terminal programs.
A few basics
When the Terminal is first opened, a message similar to the following appears:
Last login: Sat Dec 17 14:08:02 on ttyp2 Welcome to Darwin! h460db012:~ markyoung$
Line 1 shows the last time the Terminal was used. 'ttyp2 can be thought of as the "connection" to the Terminal. For example, opening another terminal window would probably show "ttyp3". Alternatively, if you have enabled Remote Login, the remote address of the last user would be visible there. If the date or last connection is unfamiliar, it could indicate someone has unwanted access to your computer.
Line 2 is just a friendly greeting from Darwin.
Line 3 is the prompt, or command prompt. It shows the machine name (h460db012), a colon, the present working directory (~) a space, the current user (markyoung) and a dollar sign (or a hash (#) if the shell has super user privileges).
The current directory
The current directory, also known as the working directory, is where you are. In the Finder, this is equivalent to having a window open and viewing the files. To determine the current directory, type in:
pwd
Which produces an output similar to this:
h460db012:~ markyoung$ pwd /Users/markyoung
pwd stands for "present working directory", and will likely output "/Users/(yourusername)". You may also notice that the current directory is displayed in a different form in the prompt. In this case, "~" is equivalent to "/Users/markyoung", the home folder. To change the current directory, use the cd command, as in
h460db012:~ markyoung$ cd Documents/ h460db012:~/Documents markyoung$ pwd /Users/markyoung/Documents
You are now in your Documents directory, just as if you had double clicked on the Documents folder in the Finder. Note how the prompt has changed to include the path "~/Documents". You can get a list of all the documents in this directory with the ls (list) command:
h460db012:~/Documents markyoung$ ls Cocoa Programming Mars.snf Microsoft User Data Pirate Girl.jpeg jeep dimensions.rtf jeep stuff.rtf macTV_SteveJobsSNLSkit.m4v starwarsWhosOnFirst.wmv
The ls has many, many options, and is worth learning. For example, ls -F will postfix a slash (/) on every directory and an asterisk (*) on every executable file.
To open one of these documents, use the open command. The open command is equivalent to double clicking a file in the Finder.
h460db012:~/Documents markyoung$ open starwarsWhosOnFirst.wmv
Job control
While Activity Monitor is useful, it's not quite as useful as working with the shell.
To get a list of every running process on your computer, type this:
ps -ax
"process status" dumps out a long list of everything that's running, along with the job number. Paired with the grep command, you can quickly determine if a process or application is running. Example,
h460db012:~/Documents markyoung$ ps -ax | grep http 164 ?? Ss 0:06.05 /usr/sbin/httpd 1377 p1 R+ 0:00.00 grep http
"/usr/sbin/httpd" confirms that Apache is running.
h460db012:~/Documents markyoung$ ps -ax | grep mysql 1379 p1 R+ 0:00.00 grep mysql
In this case however, MySQL is not running. The only process that matches "mysql" is the grep process itself (the process doing the searching).
To forcefully end a process, kill it.
h460db012:~/Documents markyoung$ ps -ax | grep Dock 91 ?? S 0:15.03 /System/Library/CoreServices/Dock.app/Contents/MacOS/Dock -psn_0_393217 1383 p1 R+ 0:00.00 grep Dock h460db012:~/Documents markyoung$ kill 91
Here, we first find the process ID of the Dock, then use the kill command with the process ID as a parameter. Alternatively, you can skip the process list and grep, and use the "combined" form:
h460db012:~/Documents markyoung$ killall Dock
Of course, the "kill" command can cause some issues if you kill the wrong process id.
For more on jobs and job control, see the jobs article.
Who Am I and Where Am I
To get the name of the current user, use the cleverly named "whoami" command (although this information is also available in the command prompt).
h460db012:~/Documents markyoung$ whoami markyoung
To get your current location, use the "hostname" command.
h460db012:~/Documents markyoung$ hostname h460db012.area2.spcsdns.net
Some Other Useful Tips
Home Directory shortcuts
Your home directory (/Users/[yourusername]) can quickly be navigated to by typing "cd" with no arguments. Alternatively, the tilde(~) character is a shortcut for the home directory of the logged in user. The tilde can prefix another user's name to become the shortcut of that user's home directory. Therefore, these commands are equivalent (assuming markyoung is the current user):
cd ~ cd ~markyoung cd /Users/markyoung
Auto-completion
At any time, when typing a command, the Terminal (or, more accurately, bash) allows for filename completion, by hitting the tab key. As a common example, type this
tail -f /var/log/sys
But, before hitting return, hit "tab". The shell will complete the filename, as the only thing in the /var/log directory that starts with "sys" is "system.log". If there's multiple matches, the shell will complete it up to the last common point. For example:
tail -f /var/log/sec
Tab in this case merely completes up to /var/log/secure.log and then beeps. This is because there are (probably) multiple files that begin with "secure.log". Pressing tab a second time will tell the shell to provide a list of matching files. For example:
h460db012:~/Documents markyoung$ tail -f /var/log/secure.log secure.log secure.log.1.gz secure.log.3.gz secure.log.0.gz secure.log.2.gz secure.log.4.gz h460db012:~/Documents markyoung$ tail -f /var/log/secure.log
This handy feature allows you to choose the one you want. If you were to type ".1", then tab, then it would complete the filename as "secure.log.1.gz" (although in this example this is a gzip'd file, which isn't tailable)
Drag and drop
To save time typing out a long path, you can drag an icon from Finder to a Terminal window, and the whole path will be filled in for you. For example, if you wanted to set the current directory to ~/Library/Preferences/, you could type in (with a trailing space):
cd
Then drag the Preferences folder onto the Terminal window, press return, and the command will work as normal. The icon in the title bar of a Finder window is also draggable in this manner.
