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Overview |
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Game of Life |
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TV episodes |
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Overview |
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Star Trek TNG |
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The Trap Door |
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Willo the Wisp |
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OS X Terminal |
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AppleScripts |
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Foxy :-) |
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Pi to 100 |
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Links |
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Mac OS X Terminal commands guide
 Page under construction
since 16th June 2008...
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The Mac OS X Terminal is an extremely useful and powerful application, but many Mac users are
put off by the fact that all interaction takes place via typed commands due to the lack of a GUI. I
am therefore creating this guide to illustrate just how useful the Terminal can be.
For example, if a CD or DVD has become stuck in the computer and cannot be ejected in the normal way, the drutil command can be used to force-eject it. If
you’re trying to eject an external hard disk in the Finder, but you get an error message saying “The disk is in use and could not be ejected”,
the lsof command can help you determine which applications you need to quit, to allow the disk to be ejected.
If you have never used the Terminal before, then check out some of these introductory articles:
1,
2,
3. (Note that, since Mac OS X is based
on Unix, many Unix tutorial articles are also applicable to the Terminal.) The three commands which you should
learn first are:
| ls | List the contents of a directory |
| cd | Move to a different directory |
| sudo | Authenticate yourself as a superuser to gain more security privileges |
You should also learn the four special directory symbols:
| . | Current directory |
| .. | Parent directory |
| / | Root directory |
| ~ | Home directory |
It’s also useful to know that OS X stores three different timestamps for every file:
| ctime | inode change time (last change time of the file’s owner, permissions, etc) |
| atime | Access time (when the data was last accessed) |
| mtime | Modification time (when the actual contents were last modified) |
Many Terminal commands have a very large number of available options, so I will only be documenting the options which I find most useful. If you want more detailed information
about a command, consult its manual page.
Table of contents
| diskutil | Interact with disks and volumes/partitions |
| drutil | Interact with CD or DVD drives |
| file | Determine the type of a file |
| find | Search for files |
| fs_usage | Display real-time filesystem activity |
| ipfw | Limit network bandwidth used by applications |
| ls | List the contents of a directory |
| lsof | List files which are currently open |
| screencapture | Take a screenshot |
| ssh | Secure SHell (create an encrypted connection) |
diskutil – View manual page
drutil – View manual page
file – View manual page
find – View manual page
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Description |
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Searches in the specified root directory (including subdirectories), and lists all files which match the search criteria.
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Wikipedia |
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Article
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Syntax |
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find root_directory search_criteria
root_directory Files and subdirectories in this root directory will be searched.
search_criteria Only files which match all these criteria will appear in the search results.
To search in directories which require high security privileges, use:
sudo find root_directory search_criteria
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Search criteria |
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| -name pattern |
The filename must match pattern (case sensitive). This can be an exact string,
such as "readme.txt", or you can use the special wildcards, including * (matches any zero or more characters)
and ? (matches any one character). These wildcards may be matched explicitly by escaping them with \. For example,
-name "*.txt" matches all files ending in .txt, and -name "questions\?.txt" matches files
with the exact name questions?.txt. More information on patterns can be found
here and
here.
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| -iname pattern |
Like -name, but the match is case insensitive.
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| -maxdepth n |
The depth of the file into the directory tree must not be greater than n directories. For example,
-maxdepth 1 will only match files in the current directory, and -maxdepth 2 will
match files in the current directory and one level of subdirectories.
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| -size Rnc |
If R is not supplied, then the file’s size must be exactly n
bytes.
If R is +, then the file’s size must be more than n
bytes.
If R is -, then the file’s size must be less than n
bytes.
For example, -size 1024c matches files of exactly 1024 bytes, and -size +2048c matches files
larger than 2048 bytes.
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| -newerXt timestamp |
The file must have a newer atime (X=a),
ctime (X=c) or mtime (X=m) than
timestamp. There are many valid formats for timestamp, including absolute (eg.
'22 Jun 2006 7:40pm') and relative (eg. '1 minute ago', '3 hours ago', etc). More
information on timestamp formats can be found here.
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| -type filetype |
The file must be of type filetype. The possible types include d
(directory), f (normal file) and l (symbolic link, also known as an alias or shortcut). |
Any of the above criteria can have -not added before it, to reverse the condition. For example, -not -name "*.txt" will
match all files whose names don’t end in .txt, and -not -newermt '22 Jun 2006' will match all files whose modification times
are not later than 22nd June 2006.
| -ls |
Print detailed information for each matching file. |
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Examples |
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find ~ -ls -iname "data*" -maxdepth 3
Search from the home directory, and print detailed information for all files whose names begin with data
(case insensitive) and are not more than 3 directories deep (including current directory).
find /Users/michaelhogg/Desktop/ -ls -newermt '22 Jun 2006' -size +1024c
Search from the directory /Users/michaelhogg/Desktop/, and print detailed information for all files which were modified after 22nd June 2006
and are at least 1024 bytes in size. |
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fs_usage – View manual page
ipfw – View manual page
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Description |
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IP firewall and traffic shaper control program. Very useful for preventing bandwidth-hungry applications from consuming all your network bandwidth (eg. uploading videos).
This command is actually extremely powerful and complex, but here I’m only documenting its bandwidth-limiting functionality. For more info, check out these articles:
1,
2,
3,
4.
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Wikipedia |
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Article
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Syntax |
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There are two steps required to set up a “pipe” to limit an application’s bandwidth usage. First, create the pipe:
sudo ipfw pipe id config bw bandwidth
This creates a pipe with an ID number id of your choice (between 1 and 65535) and maximum bandwidth
of bandwidth.
Second, attach the pipe to your network:
sudo ipfw add pipe id protocol from src to dst direction
This attaches the pipe with ID number id to the specified network protocol, limiting the bandwidth of data travelling
from src to dst in the specified direction (either in or
out).
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Bandwidth |
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The bandwidth of a pipe is specified by supplying a number (eg: 30) followed by any of these units:
bit/s
Byte/s
Kbit/s
KByte/s
Mbit/s
MByte/s
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Protocol |
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Common IP network protocol include tcp, udp and icmp. To include all network protocols,
use either all or ip.
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src & dst |
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The source and destination can be specified in the following ways:
- Any address, any port – any
- IP address, any port – 66.102.9.147
- Hostname, any port – www.google.com
- Any address, specific port – any 80
- IP address, specific port – 66.102.9.147 80
- Hostname, specific port – www.google.com 80
As an alternative to port numbers, service names can be used instead. Common service names include ftp-data, ftp,
ssh, smtp, http, pop3, imap,
https and pop3s. Examples:
- Any address, HTTP port – any http
- IP address, HTTP port – 66.102.9.147 http
- Hostname, HTTP port – www.google.com http
Note that if the source and destination imply a specific data direction, then there’s no need to specify
the direction too:
sudo ipfw add pipe 1 all from 192.168.0.2 to 66.102.9.147
In the example above, data is travelling outwards (from a local address to a remote address), so there’s no need to specify the out direction.
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Example |
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sudo ipfw pipe 1 config bw 30KByte/s
Create a pipe with ID number 1 and maximum bandwidth of 30KByte/s.
sudo ipfw add pipe 1 all from any to any 80 out
Attach the pipe with ID number 1 to all network protocols, limiting the bandwidth of data travelling
from any source (any port) to any destination (port 80) in the out
direction. |
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Disabling |
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There are four steps required to disable a pipe that’s been configured:
- Obtain the rule number for your connected pipe, using sudo ipfw list. The rule number will be a five-digit number, such
as 00100.
- Delete the rule, using sudo ipfw delete num, where num is the rule number.
- If you’ve forgotten the ID number of the pipe you originally created, check it using sudo ipfw pipe list.
- Delete the pipe, using sudo ipfw pipe delete id, where id is the pipe’s ID number.
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ls – View manual page
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Description |
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Lists the contents of a directory. By default, it lists the contents in alphabetical order, in multiple columns.
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Wikipedia |
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Article
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Syntax |
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ls options
List the contents of the current directory, using the specified options.
ls options directory
List the contents of the specified directory, using the specified options. |
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Options |
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The following options control the layout of the listing. Only one of these options should be used.
| -l |
List in long format. The following information is displayed for each file:
file mode, number of links, owner name,
group name, number of bytes in the file, mtime, and the filename. (Note: this option is the lowercase letter “L”.)
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| -1 |
Force output to be one entry per line. (Note: this option is the digit “one”.)
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Stream output format – list files across the page, separated by commas. |
The following options specify how the listing is sorted.
| -S |
Sort contents by size (largest first) instead of alphabetically.
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| -t |
Sort contents by mtime (most recently modified first) instead of alphabetically.
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| -c |
When used with -l, display ctime instead of mtime. When used
with -t, sort contents by ctime (most recently changed first) instead of mtime.
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| -u |
When used with -l, display atime instead of mtime. When used
with -t, sort contents by atime (most recently accessed first) instead of mtime.
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| -r |
Reverse the order of the sort. |
Other options include:
| -h |
When used with -l, use the following suffixes for displaying file sizes: B (byte),
K (kilobyte), M (megabyte), G (gigabyte),
T (terabyte) and P (petabyte).
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When used with -l, display complete time information for the file, including month,
day, hour, minute, second, and year.
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| -a |
Include directory entries whose names begin with a dot (.).
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| -R |
Recursively list subdirectories encountered.
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| -G |
Enable colourised output. |
Note that when specifying multiple options, a compressed format can be used for efficiency. For example:
| Standard |
ls -1 -t -c -r -G |
| Compressed |
ls -1tcrG |
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Examples |
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ls -lShT
List the contents of the current directory, in long format, sorted by size (largest first), and displaying suffixes for file sizes
and complete time information.
ls -1tcrG /Users/
List the contents of the directory /Users/, with one entry per line, sorted by ctime (oldest change first),
and colourised output. |
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lsof – View manual page
screencapture – View manual page
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Description |
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Take a screenshot, and either save it to disk or copy it to the clipboard.
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Syntax |
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screencapture options file
Take a screenshot, using the specified options, and save it to file.
screencapture -c options
Take a screenshot, using the specified options, and copy it to the clipboard. |
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Options |
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| -C |
Include the mouse cursor in the screenshot.
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| -tformat |
Specify the image format for saving the screenshot. The default is png. Other
valid formats include bmp, gif, jpg,
pdf and tiff. This option is only applicable when saving the screenshot
to a file (not copying it to the clipboard). |
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Examples |
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screencapture -C -tjpg /Users/michaelhogg/Desktop/screenshot.jpg
Take a screenshot, including the mouse cursor, and save it as a file called screenshot.jpg in the folder
/Users/michaelhogg/Desktop/, in jpg (JPEG) format.
screencapture -c -C
Take a screenshot, including the mouse cursor, and copy it to the clipboard. |
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Notes |
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This command by itself isn’t particularly useful, since the Grab application in the
Utilities folder performs all the same functions. However, this command can be very useful when called programmatically, eg. using
AppleScript
(view my example) or a
shell script.
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ssh – View manual page
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Description |
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Secure SHell – connect to another computer using an encrypted connection. Here I’m only documenting the tunneling functionality of this command. For more info
on SSH tunneling, check out this article.
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Wikipedia |
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Syntax |
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ssh -L localport:remotehost:remoteport username@sshserver
Create a secure connection to sshserver, logging in as username (you will be prompted to enter the
password). Then create a tunnel through the secure connection, from localport within your computer,
via sshserver, to remotehost:remoteport.
You can choose any unused port for localport, but port numbers less than 1024 are privileged and require root
permissions (eg. by appending sudo to the start of the ssh command).
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Example 1 |
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You have a Wi-Fi-enabled laptop, and you want to check for new emails on your BT Internet email account, by connecting to
mail.btinternet.com port 110. However, your local Wi-Fi network is
not secure, so anyone nearby with a laptop and suitable software could eavesdrop on your emails while you’re downloading them.
So you use SSH to create a secure tunnel between your computer and an SSH server on your local network (192.168.0.3), and then connect the remote end of the
tunnel to the BT Internet email server:
ssh -L 7777:mail.btinternet.com:110 michael@192.168.0.3
This creates a secure connection to 192.168.0.3, logging in as michael (enter the password when prompted). It then creates a
tunnel through the secure connection, from port 7777 within your computer, via 192.168.0.3, to
mail.btinternet.com port 110.
You now reconfigure your email application, so that instead of connecting directly to mail.btinternet.com port 110,
it connects to localhost port 7777. All data that travels between
your email application and mail.btinternet.com will now travel inside the secure SSH tunnel. Anyone nearby who attempts to eavesdrop on your emails on the
insecure Wi-Fi network will only see encrypted SSH traffic, which they can’t decode.
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Example 2 |
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You have a Wi-Fi-enabled laptop, and you want to connect to an AFP file server
at 192.168.0.3 port 548. However, your local Wi-Fi network is
not secure, so anyone nearby with a laptop and suitable software could eavesdrop on the data that you’re reading and writing.
However, the AFP file server is also running SSH, so you use SSH to create a secure tunnel between your computer and the server, and then connect the remote end of the
tunnel to AFP within the server:
ssh -L 7777:localhost:548 michael@192.168.0.3
This creates a secure connection to 192.168.0.3, logging in as michael (enter the password when prompted). It then creates a
tunnel through the secure connection, from port 7777 within your computer, to port 548
within 192.168.0.3 (the remote localhost).
Now, instead of connecting directly to afp://192.168.0.3:548 in the Finder’s “Connect to Server” prompt,
you connect to afp://localhost:7777. All AFP data that travels between your
computer and the file server will now travel inside the secure SSH tunnel. Anyone nearby who attempts to eavesdrop on your data on the insecure Wi-Fi
network will only see encrypted SSH traffic, which they can’t decode.
Note: there are two different uses of localhost here. In the ssh command, localhost
is defined relative to the remote end of the SSH tunnel (inside 192.168.0.3), so in this case, localhost refers to
192.168.0.3. When using the Finder’s “Connect to Server” prompt, localhost refers to your own computer
(the local end of the SSH tunnel).
For more info on AFP over SSH, check out this article.
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Phil
25 Jan 2010
United Kingdom |
Thanks very much, I have found the information here invaluable.
Cheers
Phil |
Jeremy Fusco
26 Jan 2010
United States |
ls and ctime.
Hi, it doesn't appear OS X's HFS+ filesystem supports ctime? The below does the expect on linux + nfs and doesn't update the creation time. Also the ls manpage doesn't show -c as an option for ctime, and no mention of ctime is in the manpage..
Tue Jan 26 10:18:16 PST 2010
bash-3.2$ echo hi >> test
bash-3.2$ ls -alc
total 8
drwxr-xr-x 3 jfusco staff 102 Jan 26 10:11 .
drwx------ 44 jfusco staff 1564 Jan 26 10:11 ..
-rw-r--r-- 1 jfusco staff 20 Jan 26 10:18 test
bash-3.2$ date
Tue Jan 26 10:19:07 PST 2010
bash-3.2$ echo there >> test
bash-3.2$ ls -alc
total 8
drwxr-xr-x 3 jfusco staff 102 Jan 26 10:11 .
drwx------ 44 jfusco staff 1564 Jan 26 10:11 ..
-rw-r--r-- 1 jfusco staff 26 Jan 26 10:19 test
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Michael Hogg
27 Jan 2010 |
Hi Jeremy,
Confusingly, "ctime" doesn't mean "creation time". It actually means "inode change time", which is the last change time of the file's owner, permissions, etc.
In Mac OS X, the real "creation time" is stored in the Spotlight metadata for a file, in the kMDItemFSCreationDate field.
In the man page for "ls", the "-c" option is defined as "time when file status was last changed". This is "ctime" (although it doesn't explicitly mention "ctime").
Hope that helps! |
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