Author Archive

More about processes and signals: writing daemons, suspending subshells.

A true wizard doesn’t just run processes, a true wizard knows how to communicate with those processes through signals to stop, restart, and even kill processes. This may sound like arcane and obscure knowledge, but if you follow along, you’ll be managing your processes like an adept in no time.

You probably already know you can examine process status with ps, but most users never embrace the full power of this great little utility.

Last month’s column, the second in this series of obscure Linux features that wizards should know, introduced Standard I/O. This month we’ll see how to take advantage of Standard I/O from a shell– including an example using named pipes (FIFOs).

In the second installment of the “Boot Camp for Wizards” series, Jerry Peek continues with a discussion of the standard I/O system.

You probably use less all the time, but do you use all its power? Jerry Peek shows you how to get the most out of less in the second part of his look at the less utility.

Developer Mark Nudelman has been working on less since version less-1, released in 1985. This month, let’s cover the Linux version less-394 (yes, it’s the 394th version), but you can also get less for other operating systems, including Mac OS X and Microsoft Windows — which makes it a great cross-platform choice for exploring files and viewing data from pipes.

Learn how to use diff3 to compare and merge files.

If a standard Linux utility doesn’t do quite what you want, adapt it.

Cygwin utilities let you do what Windows programs don’t.

Here’s the start of a series on little-known topics that wizards should know. Knowledge of the Harry Potter series not required.

More on GNU diffutils. A look into sdiff, which shows file comparisons side-by-side and lets you merge two files interactively.

Your favorite Linux shell
— bash, zsh, ksh, and more — is
probably part of the Cygwin package.

Linux gurus who also use Microsoft
Windows can have Linux-like command-line tools to make life
easier and less confusing.

Take a look at a few of the
powerful new features that make vim
Vi IMproved: a visual text-selection mode,
moving the cursor to places without text (yet), incrementing and
decrementing numbers, storing editing commands in registers,
handling binary files and different end-of-line styles, line
breaking, and screen scrolling.

Dig into some of vim’s programmable features: improvements in key mapping, a scripting language, and built-in and user-defined functions.

>Here’s the first in a series about how
vim (“ vi
improved”) is improved.

Here’s the first in a series about how vim (“ vi improved”) is improved.

More about a sophisticated package of tools for creating and editing high-quality images.

The last of a three-part series on tools for creating and editing high-quality images.

ImageMagick is a package of tools for creating and editing images that’s not easy to get started with, but is well worth the effort. Here’s an introduction, just in time for processing those summer photos.

When it’s just too hard to automate text conversion, try adding some human judgement using editing macros.

ImageMagick is a package of tools for creating and editing images that’s not easy to get started with, but is well worth the effort. Here’s an introduction, just in time for processing those summer photos.

Here’s the last in a series about new features of perennial utilities. This time: date, wc, du, and more.

What’s new with tar since it was written eons ago? A lot. Here’s the sixth of a series about new features of old utilities.

What’s new with tar since it was written eons ago? A lot. Here’s the sixth of a series about new features of old utilities.

For decades, sort has been extended over and over again to make it more and more useful. Here’s the fifth in an ongoing series about new features in familiar utilities.

For decades, sort has been extended over and over again to make it more and more useful. Here’s the fifth in an ongoing series about new features in familiar utilities.

The Friendly Interactive Shell, or fish, is” friendly” because it’s easier to use, not because it’s” dumbed down.”

Utility programs like cp have new features you may not have seen. Here’s the third in a series about some of the handiest.

Utility programs like grep have new features that you may not have seen. Here’s the second of a series of articles about some of the handiest.

vshnu is a “visual shell” that runs in a terminal window, combining navigation shortcuts with a standard shell and the power of Perl.

bash, tcsh, zsh, and their kin are all subspecies of the same beast. In search of something novel, let’s look at the first of a number of different breeds: Zoidberg.

Utility programs like ls have new features that you may not have seen. This is the first in a series about some of the handiest enhancements.

Whether you’re new to Linux or longtime Penguinista, a powerful command-line shell can boost productivity. From helpful prompts, to automatic argument completion, to time-saving command-line editing, there are many features to enjoy in modern shells. One of the most modern is the Z Shell, or zsh.

bash, tcsh, zsh, and their kin are all subspecies of the same beast. This month, let’s look at the first of a number of different breeds: a Perl shell, Zoidberg.

If you use bash, you can set an environment variable for a single command by setting the variable before the command, like this: VISUAL=/usr/bin/emacs ci -l foo.txt

Utility programs like cp have new features you may not have seen. Here’s our third of a series about some of the handiest.

Utility programs like grep have new features that you may not have seen. Here’s the second of a series of articles about some of the handiest.

Utility programs like ls have new features that you may not have seen. This is the first in a series about some of the handiest enhancements.

Spaces in filenames can cause some pesky problems. But there are workarounds.

Got text data? Linux has a variety of tools to format, process, and print it.

Dig deeper into m4, and look at included files, diversions, frozen files, and debugging and tracing.

Learn how Linux manages open files and explore a number of utilities to watch files as they grow.

Linux often gives you lots of ways to do the same thing and file transfer is no exception. We covered file transfer in three columns from March to May 2003 (available online at http://www.linux-mag.com/depts/power.html). This month let’s look at yet another variation using gFTP and some not-so-obvious details that can help you navigate all of the file transfer protocols.

A year ago, the November 2003 “Power Tools” column (available online at http://www.linux-mag.com/2003-11/power_01.html) looked into some lesser-known tools for editing text: the line editors ex and ed, and the stream editor sed.

Why would you want to give a program more than one name? How can you move quickly through the filesystem like Star Trek’s Enterprise jumping through a “worm hole”? What good are multiple views of the files in a directory? You’ll see these things and more, as we look into Linux filesystem links.

Imagine that:

While the title of this month’s “Power Tools” is “Execution and Redirection,” it’s not about about dying and going to heaven. Instead, controlling execution and redirecting input and output is an important part of managing Linux processes.

Tools with graphical user interfaces (GUIs) can be easy to learn. All of their commands and options are typically laid out on menus and dialog boxes, making it easy to discover what the tool can do. If “easy” and “intuitive” are your main criteria for programs, then a GUI tool may always be the right choice.

If you’ve worked with a group of programmers, you’ve probably used version control software like CVS. However, version control is also useful for non-programmers — for instance, for a group of technical writers producing product documentation.

In last December’s column, “Wildcards Gone… Wild” (available online at http://www.linux-mag.com/2003-12/power_01.html), we looked at ways to match groups of files in a hurry, with a minimum of typing, by using shell wildcards. Last month, we saw some of the wilder things that the Z shell, zsh, can do to make computing easier. This month we’ll mix those two topics and look at some of the most powerful zsh wildcards and similar, related features in other shells.

Linux systems have several shells available — some more powerful than others. Perhaps the most powerful shell is zsh, the Z shell. To give you an idea of the shell’s size and complexity, the zshall man page in plain-text format weighs in at more than 16,000 lines. (Rest easy. We won’t try to cover all of zsh in this month’s column.)

In an editorial a few months ago, Editor-in-Chief Martin Streicher pointed out that, whether we like Microsoft or not, it’s a fact that many of us use Windows systems. Some of us use Macintosh computers with OS X. Each of those systems has a different graphical interface. Yes, you can install the X Window System on Macs and PCs, but wouldn’t it be great to have the same standard interface to all of those systems, right out of the box?

When you type a filename on the command line (at a shell prompt), you may use filename completion to save time and typing. A popular feature, filename completion lets you type the first few letters of a file or directory name and use the TAB key to ask the shell to fill in the rest.

Linux systems use text pervasively and provide an almost- infinite number of tools to manipulate it. This month, let’s look at three lesser-known text handling tools: the line editors ex (which is usually part of the vi editor) and ed, and the stream editor, sed.

For a lot of us these days, “control” of email is more of a sad joke than a reality. New laws may not do much to stop the flood of spam, and viruses and worms keep sneaking in. As incoming messages make your server struggle and users’ inboxes groan, what’s an administrator — or a user — to do?

Graphical environments have lots of fun add-ons, such as skins, themes, and more. If you use a terminal or other shell-based applications, it’s enough to make you feel left out. This month’s “Power Tools” column aims to change that.

Last month’s feature, “Personal Post,” (available online at http://www.linux-mag.com/2003-07/email_01.html) explained how email is delivered, and also described a variety of power tools ideal for untangling a morass of messages.

Overwhelmed by email? Or is your setup okay? We’ll bet you can do better. Here are some power tools to turn your post from a pain to a pleasure.

How can you start a job from one system and finish it on another? For example:

This month, we’ll take our third and final look at transferring files between systems. The utilities we’ll check out this month, rsync and unison, analyze two sets of files and synchronize them, making the two sets identical with little or no help from you. Given a source and a destination, rsync makes all destination files match those at the source. unison works in both directions, automatically making any changes that don’t conflict and asking you about the rest.

Last month’s column (available online at http://www.linux-mag.com/2003-03/power_01.html) presented a number of ways to transfer files by hand with ssh and scp and the power of the shell. This month’s column looks at ways to transfer and synchronize sets of files automatically with ftp, sftp, and wget. Along the way, you’ll also see tips on compressed ssh and detached processes. Let’s dig in!

You’re in Cape Town, but your data is in California. You’re using a Sun system in your office, but your bleeding-edge Mozilla browser with the very cool theme and all of your favorite bookmarks is on your Linux box at home. How can you get bits from there to here without being there?

Linux systems have several ways to run jobs unattended at some later time — either once or many times. Scheduling jobs in the future is handy for system maintenance, for sending yourself reminders, and for making more practical and efficient use of your CPU by running jobs when users are away.

After a development cycle that seemed like an eternity — during which Internet Explorer supposedly “won” the “browser war” — Mozilla, the open source application suite that’s also the basis for Netscape, has become a stable and capable package with a new codebase. With Mozilla, you can browse the Web, read email and newsgroups, chat, and more. If you use multiple platforms, Mozilla is an ideal client: you can have the same, familiar Mozilla features and user interface on every machine you use (including Macintosh, Windows, Linux, Unix, just to name a few).

One Linux user is special: the superuser or root. If you manage any number of Linux boxes — even just your own desktop workstation — you’ll inevitably need root access to configure or tune the system or manage system resources. But with great wizardly powers also come risks. This month, let’s see how to manage root access and learn some powerful tricks to juggle Linux processes and shells.

How can you locate something in the filesystem with the least amount of work? You might be tempted to use a graphical (GUI) file manager, but in many cases the command line is faster. If you do a lot of work with your system, learning some pathname power tools can save you a lot of time.

Unless you’re superbly organized or have a great memory, chances are you “misplace” files from time to time. Find answers the question, “Now, where did I put that?”