SShell script wrappers can make the *nix command more transparent to the user. The most common shell scripts are simple wrappers around the third party or system binaries. A wrapper is nothing but a shell script or a shell function or an alias that includes a system command or utility.
An alias is nothing but shortcut to commands. The alias command allows user to launch any command or group of commands (including options and filenames) by entering a single word. Use alias command to display list of all defined aliases. You can add user defined aliases to ~/.bashrc file. You can cut down typing time with these aliases, work smartly, and increase productivity at the command prompt.
The $ character is used for parameter expansion, and command substitution. You can use it for manipulating and expanding variables on demands without using external commands such as sed or awk.
There are some misconceptions that shell scripts are only for a CLI environment. You can easily use various tools to write GUI and/or network (socket) scripts under KDE or Gnome desktops. Shell scripts can make use of some of the GUI widget (menus, warning boxs, progress bars etc). You can always control the final output, cursor position on screen, various output effects, and so on. With the following tools you can build powerful, interactive, user friendly UNIX / Linux bash shell scripts.
The Blue Screen of Death (BSoD) is used for the error screen displayed by Microsoft Windows, after encountering a critical system. Linux / UNIX like operating system may get a kernel panic. It is just like BSoD. The BSoD and a kernel panic generated using a Machine Check Exception (MCE). MCE is nothing but feature of AMD / Intel 64 bit systems which is used to detect an unrecoverable hardware problem.
Program such mcelog decodes machine check events (hardware errors) on x86-64 machines running a 64-bit Linux kernel. It should be run regularly as a cron job on any x86-64 Linux system. This is useful for predicting server hardware failure before actual server crash.
Like most sys admin, I’m lazy. I try to automate almost all things in order to save time. Inexperienced sys admin and help desk staff working under me finds all these tools useful. It saves their time and avoids security issues. Automation allows help desk staff to do things that they don’t have enough direct system knowledge to do themselves. However, selecting correct tool and applying correct methodology is very important.
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Is Linux is virus free? The author of foobar blog provides some insight about the same. Linux users can’t just catch a virus by email or downloading malware from the Internet, contrary to “those Windows users”. From the foobar blog post:
Then you save an email attachment under Linux, the execute flag is normally NOT set and thus, the file can’t be executed just by clicking on it. So, no luck?
This may come handy while writing cross-platform scripts.
If you don’t want to commit to the idiosyncrasies of a specific shell running on a particular platform, try the Squirrel Shell. The Squirrel Shell provides an advanced, object-oriented scripting language that works equally well on UNIX, Linux, Mac OS X, and Windows systems. Write a script once, and run it anywhere.
Squirrel is a high level imperative/OO programming language, designed to be a light-weight scripting language that fits in the size, memory bandwidth, and real-time requirements of applications like video games.
Wordpress version 2.7 has been released and can be upgraded easily using UNIX / Linux shell prompt. A few assumptions:
- Wordpress database name: wptheosblog
- Wordpress directory name: /var/www/html/theos.in
- Wordpress domain name: theos.in
- Operating system: Linux
I’ve already written a small tutorial about finding out if a file exists or not under Linux / UNIX bash shell. However, couple of our regular readers like to know more about a directory checking using if and test shell command.