TidBITS#693/18-Aug-03
=====================
Who wields the most power in the Mac world? According to
the annual MDJ Power 25, it's Steve Jobs. But Adam retains
a spot in the top five for the fourth year, and we think we
know why. Also, Kirk McElhearn explains how the command line
can simplify certain file manipulation tasks, Adam reports
on his current electronic book experiments, and we note the
releases of GraphicConverter 4.8, Security Update 2003-08-14,
TextWrangler 1.5, and DVD Studio Pro 2.
Topics:
MailBITS/18-Aug-03
Electronic Book Experiments Continue
A Mac User's Guide to the Unix Command Line, Part 3
Hot Topics in TidBITS Talk/18-Aug-03
<http://www.tidbits.com/tb-issues/TidBITS-693.html>
<ftp://ftp.tidbits.com/issues/2003/TidBITS#693_18-Aug-03.etx>
Copyright 2003 TidBITS Electronic Publishing. All rights reserved.
Information: <[EMAIL PROTECTED]> Comments: <[EMAIL PROTECTED]>
---------------------------------------------------------------
This issue of TidBITS sponsored in part by:
* Make friends and influence people by sponsoring TidBITS!
Put your company and products in front of tens of thousands of
savvy, committed Macintosh users who actually buy stuff.
For more information and rates, email <[EMAIL PROTECTED]>.
* READERS LIKE YOU! Help keep TidBITS great via our voluntary <------ NEW!
contribution program. Special thanks this week to Mervyn Smith,
Edward Floden, and Micah Alpern for their generous support!
<http://www.tidbits.com/about/support/contributors.html>
* SMALL DOG ELECTRONICS: Great Deals on iBooks! <--------------------- NEW!
iBook G3/700 12in Only $759! iBook G3/800 Combo Only $1,129!
iBook G3/800 14in with Combo drive Only $1,259!
Visit: <http://www.smalldog.com/tb/> 802-496-7171
* Creo's Six Degrees is time-freeing technology that automatically <- NEW!
connects messages, files, and people on your desktop so you can
quickly navigate through projects. Free 30 day trial version!
==> <http://www.creo.com/sixdegrees/index.asp?id=tidbits> <==
* Bare Bones Software TextWrangler 1.5 -- General-purpose tool for <- NEW!
composing, modifying, and transforming text. Now with full
AppleScript support! US$49. For more info, to download a demo,
or to purchase a copy, visit <http://www.barebones.com/>.
---------------------------------------------------------------
MailBITS/18-Aug-03
------------------
**TidBITS Publisher Adam Engst #4 in MDJ Power 25** -- The results
of the annual MDJ Power 25 survey are out, and TidBITS publisher
Adam Engst has maintained a spot in the top five for the fourth
consecutive year - fourth place this time around. The MDJ Power 25
attempts to determine who truly wields power and influence in the
Macintosh community by asking for the opinions of long-time
industry insiders. For the second year in a row, Adam was the
only member of the top five who is not an Apple employee. Apple
CEO Steve Jobs was once again voted the most powerful person in
the Mac industry (surprising no one), followed in second place by
Apple's Chief Software Technology Officer Avie Tevanian and Apple
Vice President of Software Engineering Bertrand Serlet in third
place, with Vice President of Design Jonathan Ive in fifth. The
reason for Adam's continued high ranking? The industry insiders
consider TidBITS required reading, and they acknowledge Adam's
continual efforts behind the scenes to make the Macintosh
community a better place.
<http://www.macjournals.com/>
<http://db.tidbits.com/getbits.acgi?tbser=1246>
There's a trend in the voting toward assigning more power
and influence to Apple employees (and primarily high ranking
executives at that). In 2000 and 2001, 10 Apple employees made
the list, 14 in 2002, and 16 in 2003. The spots they've taken have
come at the expense of independent Macintosh developers (seven
in 2000 and eight in 2001, but only three this year, if you count
Dr. John E. Kelly of IBM, who makes the list only because he's in
charge of the group that builds the PowerPC G5 chip). The numbers
of writers, journalists, and publishers has dropped only slightly
each year, starting at eight in 2000, dropping to seven in both
2001 and 2002, and six in 2003. One question is whether the trend
reflects a concentration of power in Cupertino, which could impact
the overall health of the Macintosh world, or if MDJ's choice
of industry insiders (at least those who take the time to vote)
has become skewed in some way toward Apple. There's also some
potential confusion between power and influence: Apple employees
wield great amounts of power (since almost anything they do
affects Apple customers), but people like Adam, David Pogue of
the New York Times (6th place), Ric Ford of MacInTouch (12th
place), and Rick LePage of Mac Publishing (14th place) influence
what we know, what we talk about, and the way we think. [GD]
**Apple Releases Security Update 2003-08-14** -- Apple has
released Security Update 2003-08-14 for Mac OS X, a 1.1 MB
download available via Software Update. The release corrects
an off-by-one programming error in a FreeBSD networking function
which could potentially be exploited to give a remote user
root-level access to a Mac OS X system. The problem was originally
found in the wu-ftpd FTP server, and impacts FreeBSD Unix and
other FreeBSD-derived operating systems, including Solaris and
some flavors of Linux. As of this writing, Apple has not provided
any substantive information about the update; however, there are
no known instances of this potential problem having been exploited
under Mac OS X or any other operating system. [GD]
<http://www.info.apple.com/usen/security/security_updates.html>
<http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0466>
<http://www.info.apple.com/usen/security/index.html>
**TextWrangler 1.5 Adds Scripting, Syntax Coloring** -- Bare Bones
Software has released the latest version of its streamlined text
editor, TextWrangler 1.5 . The primary new feature is the addition
of full AppleScript support to enable TextWrangler to participate
in automated workflow solutions involving text files. Better yet,
any set of actions in TextWrangler can be recorded as an
AppleScript script, and any script can be attached to built-in
menu commands. TextWrangler 1.5 also now boasts syntax coloring
and source-code navigation for code in Fortran, Java, Object
Pascal, Perl, Python, Rez, Tcl, TeX, and Unix shell script.
Despite including BBEdit's core text editing engine, TextWrangler
shies away from some of BBEdit's more-powerful features, such as
flexible HTML tagging, integration with CodeWarrior, support for
version control systems, and more. However, since TextWrangler
costs $130 less than BBEdit, it has become popular with folks who
seldom work with HTML files, those who find BBEdit's additional
features overwhelming, and those who want much of BBEdit's power
for a lower price. TextWrangler 1.5 sells for $50, but upgrades
are free to registered users. It requires Mac OS X 10.2 or later
with Mac OS X 10.2.6 strongly recommended. A 30-day, time-limited
demo is available as a 7.6 MB download. [ACE]
<http://www.barebones.com/products/textwrangler/>
**DVD Studio Pro 2 Arrives** -- Four months after announcing DVD
Studio Pro 2 at the National Association of Broadcasters (NAB)
conference, Apple has now shipped the professional DVD creation
tool. DVD Studio Pro 2 is an extensive, ground-up rewrite of
the original that incorporates technologies acquired when Apple
purchased Spruce Technologies in 2001. The new version adds
timeline-based track editing, a menu editor for customizing DVD
menu systems, an improved MPEG-2 encoder, and plenty of design
templates. The program's interface has been revamped as well,
offering three different modes: Basic (similar to iDVD), Extended
(more customization options), and Advanced (no pixel left
unturned). DVD Studio Pro 2 integrates with Final Cut Pro 4, which
was also announced at NAB and began shipping in June (see "Apple
Ships Final Cut Pro 4" in TidBITS-684_). The full version of DVD
Studio Pro 2 costs $500, and upgrades from DVD Studio Pro 1.5
cost $200 (those who purchased version 1.5 between 06-Apr-03 and
15-Aug-03 can upgrade for a $30 shipping fee through Apple's
Up-To-Date program). You need a Mac with at least a PowerPC G4
processor running at 733 MHz or better and an AGP graphics card,
Mac OS X 10.2.6 or later, and a DVD drive for installation;
although a SuperDrive isn't required to use the program, it
is needed to burn projects to DVD-R media. [JLC]
<http://www.apple.com/dvdstudiopro/>
<http://db.tidbits.com/getbits.acgi?tbart=07229>
<http://www.apple.com/dvdstudiopro/uptodate.html>
**GraphicConverter 4.8 Available** -- In a product release we
missed a couple of weeks ago, Lemke Software has updated its
venerable image editing application GraphicConverter to version
4.8. As with previous updates, it's a wonder that anyone at Lemke
gets any sleep: GraphicConverter 4.8 rolls together numerous
improvements and fixes. For example, a new unskew effect has been
added, as has the capability to swap color channels. Palm support
has been improved with the addition of importing support for Foto
PDB files and Palm image streams. Also, support for reading images
directly from digital cameras and detecting images generated from
Canon and Kodak cameras has been improved. GraphicConverter 4.8
runs under Mac OS 8.6 or later, including Mac OS X, costs $35
shareware, and is a 4.3 MB download. [JLC]
<http://www.lemkesoft.de/en/graphcon.htm>
<http://www.lemkesoft.de/en/graphdownld_en.htm>
Electronic Book Experiments Continue
------------------------------------
by Adam C. Engst <[EMAIL PROTECTED]>
I remain fascinated by the evolution of electronic books, both
those that started life on paper and those written purely for the
digital world, so I'm continuing my experiments with both types.
**New 10 Quick Steps Guides** -- Radio host David Lawrence (of
Online Tonight and the new David Lawrence Show) has started a
series of ebooks that he calls the 10 Quick Steps Guides. Each $10
guide follows a 10-step format that provides either a process or
tips for accomplishing the task at hand. In an unusual twist, the
10 Quick Steps Guides are available both in PDF (formatted for
reading onscreen) and in MP3 format for listening.
<http://www.onlinetonight.net/>
<http://thedavidlawrenceshow.com/>
<http://www.10quicksteps.com/>
I've written two 10 Quick Steps Guides, one on avoiding spam that
offers a series of interconnected strategies for getting spam out
of your face, and another on how to make a Wi-Fi connection, using
the information I gathered when writing The Wireless Networking
Starter Kit.
<http://www.10quicksteps.com/spam/>
<http://www.10quicksteps.com/wifi/>
<http://wireless-starter-kit.com/>
So far, my Wi-Fi 10 Quick Steps Guide is outselling the Stopping
Spam 10 Quick Steps Guide by about two to one, which surprises me.
I expected the Stopping Spam 10 Quick Steps to be more popular
both because I thought spam was a larger concern and because I
wrote it completely from scratch, instead of repurposing the
content from a more extensive book people can buy for about $25.
That says to me there is a distinct audience for whom a concise
electronic guide is more attractive than a longer traditional
book.
Amusingly, David had an ex-spammer on his show shortly after
the Stopping Spam 10 Quick Steps Guide came out, and the guy both
confirmed what I described and agreed that the advice would indeed
have worked against him. If your spam load has become distressing,
check out the Stopping Spam 10 Quick Steps Guide for my
recommendations, which go against the usual approach of
setting up new email accounts each time an existing account
starts receiving too much spam.
Also interesting is the fact that the PDF versions of the books
outsell the MP3 versions about four to one. Most electronic
publishers probably wouldn't do even that well, but it makes sense
given that people think of David as a radio personality and know
his voice. The audio versions of the 10 Quick Steps Guides should
appear at Audible.com soon as well, so I'll be curious to see how
well they fare there.
**iPhoto 2 VQS Goes Electronic** -- Moving from ebooks created
to be read onscreen to those converted from traditional books,
I've now made my most recent book, iPhoto 2 for Mac OS X: Visual
QuickStart Guide, available in PDF format from Lockergnome. As
with The Wireless Networking Starter Kit, which Glenn Fleishman
and I also sell through Lockergnome as a PDF, the price of the
electronic version of the iPhoto VQS isn't meant to cannibalize
sales of the paper version, so I set it at $14, or roughly the
cost of the paper version before shipping.
<http://store.eSellerate.net/a.asp?c=0_SKU5164366758_AFL0770764229>
<http://tutorials.lockergnome.com/>
Of course, anyone who has already purchased the paper version
of the iPhoto 2 VQS can get the electronic version for free
(see the first page of the book), so the main reason to buy
the electronic version is to avoid high shipping costs to
international destinations, to take advantage of enhanced
searching and navigation features, or if you simply don't want
to use paper unnecessarily.
About 180 people have requested the free electronic version
after buying the paper version so far; about 500 have downloaded
the free (for anyone) electronic version of the older iPhoto
1.1 book, which you can access by sending email to
<[EMAIL PROTECTED]>.
**Changing Roles and Assumptions** -- The main realization these
experiences have triggered for me is that electronic books confuse
much of the standard terminology that surrounds book publishing.
We're used to authors writing lengthy books for publishers, who
then rely on bookstores for sales, but in the electronic book
publishing world, roles are different and assumptions change.
Electronic books written for purely digital distribution are
seldom as long as a traditional paper book because people don't
want to read as much at the computer screen, because there's no
minimum size necessary for a book to avoid looking like a
pamphlet, because many ebooks are relatively inexpensive, and
frankly, because it's easier for the author. In fact, many ebooks
are roughly the same length as a hefty feature article in a
magazine; the main difference is that if you as a reader are
looking for information on a particular topic, finding it in
a current magazine is essentially happenstance, whereas you may
be able to find an ebook that addresses your needs precisely.
In the ebook world, there's also little difference between
publishers and bookstores. Traditional publishers put most of
their effort into creating the book and pushing it into sales
channels, but almost none into direct sales. That results in
royalty rates for authors that top out at about 20 percent of
the selling price to bookstores (the selling price is usually
about half of the cover price).
In contrast, ebook publishers generally rely on authors to provide
a mostly polished text in return for up to 50 percent royalties
on the full price, and they put much more effort into sales and
marketing; for instance, David frequently promotes the 10 Quick
Steps Guides on his radio shows. Ebook publishers are also often
happy to sell each other's books, and to give authors even higher
percentages on direct sales the authors generate. That's why
you'll see some of David's 10 Quick Steps Guides on GnomeTomes,
and why David is setting up affiliate deals with companies like
Audible.com.
All that said, the economics of ebook publishing still don't, for
the most part, compare to traditional book publishing. An average
computer book might sell 8,000 to 12,000 copies and generate
between $5,000 and $15,000 for the author. In contrast, my
experience is that ebooks are more likely to sell in the 200
to 2,000 range and generate more like $1,000 to $4,000 for the
author. The big difference is in the time and effort necessary
to create an ebook - it may be a matter of days or weeks from
start to finish instead of months for a traditional book.
Don't make the mistake of assuming that these sales levels mean
that the overall viability of electronic books is necessarily
low. That's because each of these electronic publishers has their
own audience - David's radio listeners, or subscribers to the
Lockergnome newsletters - and there isn't necessarily much overlap
in members, even if people in both audiences are interested in
the same content. This fact is another reason these electronic
publishers are more like bookstores - a bookstore in one town
doesn't generally compete with a bookstore in another town because
they have different geographic audiences, and the people buying
from Lockergnome may never visit David's 10 Quick Steps Web site.
It's also highly unusual for a single bookstore to sell a few
hundred copies of a book, as has happened with my 10 Quick Steps
Guides and with the PDF of The Wireless Networking Starter Kit
on Lockergnome, so I'm extremely happy with those results. The
trick is that we need to create more of these topic-appropriate
bookstores for electronic books; once that's done, electronic
books might be able to achieve the sales levels of traditional
books.
A Mac User's Guide to the Unix Command Line, Part 3
---------------------------------------------------
by Kirk McElhearn <[EMAIL PROTECTED]>
Lesson 3: Moving, Copying, and Deleting Files and Directories
In the previous two installments in this series, we looked at the
basics of using the Terminal to access the Unix command line at
the heart of Mac OS X, and then at how to use the Terminal to move
around your Mac's file system. You might want to skim those
articles for a quick refresher on some of the basics.
<http://db.tidbits.com/getbits.acgi?tbser=1238>
One of the strongest features of the Mac OS X Finder is its
capability to make file management actions so easy that they
seem effortless. When you drag a file's icon from one window to
another, for example, the Finder puts a graphical face on a basic
action, that of issuing a command to move a file from one location
to another.
It's certainly quicker and easier to move icons in Finder windows
than to type commands, but the command line offers advantages over
using the Finder for moving, copying, or deleting files and
folders (or directories). Here are just a few:
* You can copy or move files from one directory to a distant
directory, without having to navigate through intermediate
windows.
* You can easily copy or move multiple files using wildcards
(a wildcard is a single character that represents one or more
other characters). You can even select which files to copy
according to certain attributes, such as parts of file names
or extensions.
* You can copy or move files that are hidden by the Finder.
* You can move and rename a file or directory with just one
command.
* You can delete files or directories quickly, and use wildcards
to match certain file name strings (such as .jpg, .rtf, and so
on). These deletions are irreversible, so be careful!
* You can delete files that the Finder refuses to delete;
occasionally, a recalcitrant file you have placed in the Trash
just won't go away. Using the command line, you can eliminate
it for good.
As you become more familiar with working with the command line,
you will discover more advantages to using it for file
manipulation.
**A Caveat on Moving and Copying Files** -- The Mac OS has
historically used a unique way of saving files: many files are in
two parts, called the data fork and the resource fork. Back in the
days of Mac OS 9 and earlier, the data fork contained data (the
contents of a file, or code for applications) and the resource
fork contained settings, icons, and other information. Most files
used this multi-fork system, and, if you ever copied Mac files
to a PC-formatted floppy disk and then looked at it on a Windows
computer, you could have seen additional folders copied together
with your files. These folders held resources forks; since Windows
doesn't understand multi-forked files, putting the resource forks
in a separate folder was one way of keeping Windows from deleting
them altogether. Unfortunately, and almost shockingly, the
standard Unix commands available in Mac OS X don't understand
resource forks either.
When copying or moving files containing a resource fork, this
can be a serious problem: some files still contain information
in a resource fork, especially applications and those files
created by Classic applications, as well as some Mac OS X-native
applications. The cp and mv commands strip any resource forks they
come across, potentially rendering the files useless. Apple
addressed this problem by creating some additional commands,
called CpMac and MvMac (the capitalization is important here),
to resolve these issues, but for some reason, these commands are
installed only with the Developer Tools, so most people probably
don't have them installed. These command line tools enable you
to copy and move files while retaining their resource forks,
thus ensuring that everything you copy or move with them remains
usable.
Another command, called ditto, has a -rsrcfork option, which, like
CpMac and MvMac, allows you to retain resource forks when copying
files.
**Copying Files with cp** -- The cp (copy) command does exactly
what its name suggests: it copies files from one location to
another. (This is the equivalent of pressing Option while dragging
files in the Finder from one window to another on the same
volume.) In its simplest use, cp copies a file (specified by
its file name, with either a relative or absolute path) to a
directory (also specified by its name, with either a relative
or absolute path). The basic form is as follows:
% cp source destination
With this in mind, let's look at a few examples of copying files.
% cp ~/Documents/MyFile.rtf ~/Public
In the above example, I copied the file "MyFile.rtf" from
the Documents directory in my Home directory to the Public
directory, a location where any user can access files. As you
can see, the first part, cp, is the command, the second,
~/Documents/MyFile.rtf, is the source, and the third part,
~/Public, is the destination. Both the source and destination
in this example use absolute file paths; I could be anywhere
in the file system when running this command.
However, if I were already in the Documents directory, I wouldn't
need to use an absolute file path for the source. Since it's
perfectly legal to mix absolute and relative file paths in a
command, I could merely type the following:
% cp MyFile.rtf ~/Public
When copying files in this simple form, the source is a file name
and the destination is a directory. (Though the destination can
also be a file name; see below for more ways to use cp.) But the
source can also be multiple file names. When executing this
command, the shell (which is the Unix program that accepts your
typed commands, interprets them, and displays the results) checks
the contents of the directory you refer to, making sure that the
file or files exist. If there are several files listed in what
you've typed, and they all exist, then the shell goes ahead and
copies them all to the destination. You can run a command like
this to copy the three files after the cp command to the Public
directory:
% cp MyFile1.rtf MyFile2.rtf MyFile3.rtf ~/Public
**Using Wildcards to Copy Files** -- For an even shorter version
of the previous command, you can use a wildcard and save some
typing:
% cp MyFile* ~/Public
The * wildcard tells the shell to look for all files whose names
begin with MyFile, and copy them to ~/Public. Of course, if you
have 10 files like that, all 10 will be copied. If you want only
the first three copied, you must enter each name individually, or
you could use the following command:
% cp MyFile[1-3].rtf ~/Public
If you want to copy all .rtf files from the source directory, you
can use the following:
% cp *.rtf ~/Public
This command copies all files ending with .rtf to the Public
folder. You can use the asterisk wildcard at any location in
a file name.
**Warning: Copying Files Replaces Existing Files** -- By default,
the cp command silently replaces any like-named files in the
destination, unlike the Finder, which displays an alert asking
if you really want to replace them. The same goes for the mv
command (see below). This is one of the dangers of using the
command line - new actions call for new habits, and the safest
way to work with these two commands is to use the -i (interactive)
option, which tells the shell to ask you if any files with the
same name are present. When using this option, type y for yes
(to replace files) and n for no. Here's an example:
% cp -i MyFile1.rtf New_Directory/
overwrite New_Directory/MyFile1.rtf? y
%
If I had typed n at the overwrite question, the command would have
stopped without doing anything.
**Copying a File and Changing Its Name** -- In the above examples,
the sources used were files and destinations directories. But the
destination can also be a file name. This is useful if you want to
copy a file and change its name at the same time. For example, to
copy MyFile.rtf to your Public folder, renaming it MyFile1.rtf,
run the following command:
% cp MyFile.rtf ~/Public/MyFile1.rtf
You can do the same thing to make a copy of a file, with a
different name, in the same folder. Just run the command like
this:
% cp MyFile.rtf MyFile1.rtf
**Copying Directories with cp** -- You can use cp to copy
directories as well as files, but it works a bit differently.
For cp to work with directories, it needs the -R (recursive)
option. The -R option tells cp to copy not only the directory
specified, but also all sub-directories it contains as well
as any other contents. To copy a directory, you need to run
a command using this basic form:
% cp -R source destination
All the other options and ways of copying, shown above for files,
work the same with directories. Note, however, that while you can
change the name of a directory during a copy, you cannot change
the name of its sub-directories or other contents.
**Moving Files and Directories with mv** -- The mv (move) command
moves files or directories from one location to another. It works
just like when you drag files from one Finder window to another
on the same volume. Note that if you run the mv command across
volumes, the files or directories are removed from their original
location, whereas the Finder normally copies them across volumes
unless you hold down Command while dragging them. The mv command
thus acts like a cut and paste operation, cutting the file or
directory from its original location, and pasting it in its new
location. The mv command works almost exactly like the cp command,
the main exception being that you never have to use the -R option
to move directories. To use mv, try the examples described above,
substituting mv for cp.
% mv MyFile.rtf ~/Public/MyFile.rtf
In the above example, the file called MyFile.rtf is moved to my
Public folder. The operating system first writes the file, then,
after checking to make sure the copied file was written correctly,
it deletes the original.
By default, the mv command (just like cp) replaces any like-named
files in the destination. This behavior is unlike the Finder,
which displays an alert, asking if you really want to replace
them. You can run the mv command with the -i (interactive) option,
as with many commands, to protect against this possibility.
**Renaming Files and Directories with mv** -- Since you can change
the name of the destination when moving files or directories with
mv, you can also use it to rename items, such as in this example:
% mv MyFile.rtf NewlyNamed.rtf
Unfortunately, renaming a bunch of files at once with wildcards
(such as prefixing each of many files with a specific string)
isn't trivial; the best way to do that is with the Add and Trim
AppleScript scripts that Apple includes with Mac OS X; you can
find them in /Library/Scripts/Finder Scripts.
**Creating Directories with mkdir** -- We have seen above how to
move and copy files from one directory to another, but you may
also need to create directories to put these files in. The mkdir
(make directory) command is easy to use. Here's an example:
% mkdir Test
This command creates a new directory, called Test, in the current
directory. Since the command does not begin with a /, the shell
knows that you are specifying a relative path. If you want to
create the same directory in, say, your Documents directory, you
could run the above command after using cd (change directory) to
move to that directory, or, from anywhere, run the following:
% mkdir ~/Documents/Test
The mkdir command can also make several directories at a time.
If you want to create three directories, called Test1, Test2,
and Test3, in the current working directory, you can run the
following:
% mkdir Test1 Test2 Test3
If you want to create directories in hierarchy, mkdir can help
as well. The only condition is that you set up your command in
hierarchical order, creating the parent directory before the
sub-directory, and before the sub-sub-directory, and so on.
To create a series of directories and sub-directories like this:
Test1/Test2/Test3
you need to run the command as follows:
% mkdir -p Test1/Test2/Test3
The -p (path) option tells the command to create each intermediate
directory as required. The command first creates the Test1
directory, then the Test2 sub-directory, and finally, further
down in the hierarchy, Test3.
**Removing Directories with rmdir** -- The rmdir (remove
directory) command is self-explanatory: it lets you remove
directories, deleting them forever. Like the rm command that
works on files, this command is extremely powerful: once you
remove a directory, there is no getting it back.
However, rmdir works only with empty directories, whereas rm works
with both directories and files, thus enabling you to delete a
directory and the files in it. You may find it easier to use rm
for both files and directories - it's easier to use one command
instead of two.
To delete an empty directory, run the following:
% rmdir Directory1
You can remove several empty directories in one command. Just
separate their names with single spaces, specifying either
just their names (for relative paths, within the current working
directory), or their paths (for absolute paths). Here's an example
that removes three directories at once - Directory1, OldDocuments,
and Video - and uses a different way of specifying each one:
% rmdir Directory1 ~/Documents/OldDocuments ../Video
You can also use rmdir to remove a hierarchy of directories, as
long as all the directories are empty. Use the -p (path) option
as follows:
% rmdir -p Directory1/Directory2/Directory3
One disadvantage to using the rmdir command is that, unlike the
rm command, it has no -i (interactive) option, which asks you
to confirm the deletion, and no -v (verbose) option; these
deficiencies limit its value.
**Removing Files with rm** -- The rm (remove) command is one
of the most powerful and dangerous commands you can use in the
Terminal. Be forewarned: when you remove a file with rm, it is
deleted forever. Although some file recovery programs may be able
to find files deleted in this manner, it is safest to assume that
files eliminated with rm are gone for good. Be even more careful
with rm if you use it with the * wildcard, since it could wipe
out all the files in a directory with no warning.
Although many Unix commands are safe to run, even if you have
little experience, rm is like a loaded gun. For this reason, you
should use it with the utmost care. However, there is a simple way
to apply a safeguard to rm (and others); see below for a safety
measure that takes the worry away.
Running the rm command is relatively simple. Look at the contents
of this directory with ls:
% ls
File1 File2 File3
To remove one of these files, run the following:
% rm File1
Check to make sure it worked with ls again:
% ls
File2 File3
You can see that the file you removed is indeed gone; it no longer
shows up in the list.
**Safer Ways Remove Files** -- The first way of removing files, as
shown above, is really for those people who are confident with the
command line. It's working without a net, though, and there is a
simple safeguard you can use to protect yourself. The rm command
has an option, -i (for interactive), which tells the shell to ask
you to confirm that you really want to delete each file. To use
this option, run the command as follows:
% rm -i File2
The shell asks you to confirm.
remove File2?
Type y for yes or n for no.
remove File2? y
If you type y, the file will be deleted. If you type n, the file
will not be touched. In both cases, the Terminal displays a new
prompt; it gives no other information, and you need to use ls
again to see what's in the directory.
Want an even safer way to remove files? Mimic the way the Finder
does it and move them to the Trash. Then they won't be deleted
until you empty the Trash manually. Try this mv command:
% mv MyFilertf ~/.Trash
**Getting More Feedback with rm** -- The rm command has another
option, -v (verbose), which shows the names of files as it removes
them. If you use this option, the shell shows the following:
% rm -v File3
File3
%
I have added the prompt after the file removal to illustrate how
this displays. All this option does is show the name of the file,
but it can serve to confirm exactly which file has been removed.
Of course, if you made a typo and removed the wrong file, it's
too late!
**Removing Directories with rm** -- Although you can use rmdir for
removing empty directories, the rm command also lets you do this
through the -d option. To remove a directory, use the following
command, along with the -i and -v options for additional security:
% rm -div Directory1
The rm command can also remove directories recursively, using
the -r (recursive) option, deleting a directory and all its
subdirectories, as well as any files they contain. This is like
dragging a folder, containing sub-folders and files, to the Trash
in the Finder, except you can't drag it back out of the Trash if
you want to keep it. If rm is a loaded gun, rm -r is a loaded
bazooka. I cannot stress strongly enough how dangerous this
command is, since you could blow away large numbers of files
with a single mistake!
Let's look at how this works, and how you can use the -i option
for minimal protection. First, create a few nested directories:
% mkdir -p Directory1/Directory2/Directory3
Then, to remove all three of these directories, run the following:
% rm -ir Directory1
remove Directory1? y
remove Directory1/Directory2? y
remove Directory1/Directory2/Directory3? y
Obviously, if you don't use the -i option, the command just
removes all the directories without any feedback. But what if
you decide you don't want to remove one of the directories?
You can type n at any point to keep it and each directory above
it. Watch what happens then:
% rm -ir Directory1
remove Directory1? y
remove Directory1/Directory2? y
remove Directory1/Directory2/Directory3? n
rm: Directory1/Directory2: Directory not empty
rm: Directory1: Directory not empty
If, at any point in the hierarchy, you don't want to delete a file
or directory, the system cannot let you keep an item without its
parent directory. In the above example, the decision to not remove
Directory3 means that Directory2 (its parent directory) could not
be deleted; Directory1 (the parent of Directory2) also could not
be deleted, so none of these three directories will be removed.
**Summing Up** -- This installment has shown you the essential
commands for copying, moving, and deleting files and directories,
as well as creating directories. These commands - cp, mv, rm,
mkdir and rmdir - offer the same basic functions as normal Finder
actions, but, as some of the examples show, offer more power and
flexibility in certain situations. While the Finder remains easier
to use for most operations, these commands give you a powerful
alternative, with some capabilities the Finder cannot offer.
[Kirk McElhearn is a freelance writer and translator living in
a village in the French Alps. This article is an excerpt from his
forthcoming book, Unix for Mac OS X: Learning the Command Line,
to be published by Addison-Wesley in 2003.]
<http://www.mcelhearn.com/unix.html>
PayBITS: Did this article help you dip your toes into Terminal?
Consider supporting Kirk with a few bucks via PayPal!
<https://www.paypal.com/xclick/business=kirk%40mcelhearn.com>
Read more about PayBITS: <http://www.tidbits.com/paybits/>
Hot Topics in TidBITS Talk/18-Aug-03
------------------------------------
by TidBITS Staff <[EMAIL PROTECTED]>
**Scams aimed at users of PayPal and other sites** -- More details
on the PayPal scam spam, along with some complaints about how
PayPal and eBay deal with reports. (9 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2031>
**Text snippets while away from home** -- Everyone seems to be
interested in keeping interesting snippets of text, but what do
you do if you're away from home? Solutions here. (4 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2032>
**Comments on VXA-2** -- Adam switched from the Exabyte VXA-1 tape
drive to a FireVue-based hard drive backup strategy, but a reader
is curious if anyone has tried Exabyte's VXA-2 tape drives.
(1 message)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2033>
**Apple's share of the PC market** -- Every press article likes
to point out that Apple has only 3 to 5 percent of the overall
market, but does that matter at all? Some say yes, but others
think it's a bogus statistic. (14 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2035>
**Serious data archiving** -- We don't pretend that a hard drive-
based backup strategy is appropriate for serious data archiving,
so what is? (3 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2036>
**Building a better challenge-response system** -- Challenge-
response systems for reducing spam aren't inherently evil,
it's just that most have significant problems. What's necessary
to build a better one? (4 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2037>
**International power adapters** -- What do you need if you're
going to travel around the world with your PowerBook or iBook?
Read this thread for the answers. (7 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2038>
**Complaints about the 17" PowerBook** -- After Michael Shappe's
review, there had to be some complaints, but we were expecting
more than one. (3 messages)
<http://db.tidbits.com/getbits.acgi?tlkthrd=2039>
$$
Non-profit, non-commercial publications may reprint articles if
full credit is given. Others please contact us. We don't guarantee
accuracy of articles. Caveat lector. Publication, product, and
company names may be registered trademarks of their companies.
This file is formatted as setext. For more information send email
to <[EMAIL PROTECTED]>. A file will be returned shortly.
For information: how to subscribe, where to find back issues,
and more, email <[EMAIL PROTECTED]>. TidBITS ISSN 1090-7017.
Send comments and editorial submissions to: <[EMAIL PROTECTED]>
Back issues available at: <http://www.tidbits.com/tb-issues/>
And: <ftp://ftp.tidbits.com/issues/>
Full text searching available at: <http://www.tidbits.com/search/>
-------------------------------------------------------------------
