Linux Certification

‘Getting the right cropping values using GIMP

In 5 steps:
Where to find the cropping values
1. Open up GIMP.
2. Open one of the images in GIMP.
3. Using the Rectangle Select Tool (hotkey “R”), select the area you want to be cropped.
4. Note the X, Y, Width and Height values GIMP gives you (have a look at the picture, you can find them in the GIMP main window).
5. Close GIMP (or leave it open if you plan to use it again soon).

‘Let’s have a look at a rather simple mencoder command that should create a WMP-compatible MPEG file:

[rechosen@localhost ~]$ mencoder
-oac lavc -ovc lavc -lavcopts acodec=mp2:vcodec=mpeg2video:mbd=1:vbitrate=1800 -of mpeg -o

Replace “
” with the video source (for example a file or a DVD scene) and “” with the file you want the output to be written to (e.g. “samplemovie.mpg” or “dvdbackup.mpeg”). You can also replace the value after “vbitrate=” with a higher or lower bitrate, depending on the desired quality of the outputfile (you could also leave it away entirely, but it will then default to 800, which is quite low and therefore pretty much only suitable for very low resolution movies).

‘If you use bash for scripting you will undoubtedly have to use conditions a lot, for example for an if … then construct or a while loop. The syntax of these conditions can seem a bit daunting to learn and use. This tutorial aims to help the reader understanding conditions in bash, and provides a comprehensive list of the possibilities. A small amount of general shell knowledge is assumed.

Difficulty: Basic – Medium
Introduction

Bash features a lot of built-in checks and comparisons, coming in quite handy in many situations. You’ve probably seen if statements like the following before:

No matter how stable the Linux kernel is, things like hardware failures can still lock up your system quite effectively. If you ever encounter a case like that, rebooting is pretty much the only option. However, there is rebooting and rebooting. This solution describes a way to reboot your system that will do things like terminating all processes, syncing the remounting the disks, in order to prevent damage as much as possible. This can save you a lot of fscking and data loss.
What this is and what this isn’t

If you use bash for scripting you will undoubtedly have to use conditions a lot, for example for an if … then construct or a while loop. The syntax of these conditions can seem a bit daunting to learn and use. This tutorial aims to help the reader understanding conditions in bash, and provides a comprehensive list of the possibilities. A small amount of general shell knowledge is assumed.

Difficulty: Basic – Medium
Introduction

Bash features a lot of built-in checks and comparisons, coming in quite handy in many situations. You’ve probably seen if statements like the following before:

Translate, squeeze, and/or delete characters from standard input, writ- ing to standard output. -c, -C, –complement first complement SET1 -d, –delete delete characters in SET1, do not translate -s, –squeeze-repeats replace each input sequence of a repeated character that is listed in SET1 with a single occurrence of that character -t, –truncate-set1 first truncate SET1 to length of SET2

The mysql program provides a curses-based interface to the SQL-based database server daemon, mysqld(1). Full fuller documentation, refer to the HTML documents installed with the package.
OPTIONS

The mzip command is used to issue ZIP disk specific commands on Linux, Solaris or HPUX. Its syntax is:

mzip [-epqrwx]

Mzip allows the following command line options:

e
Ejects the disk.
f
Force eject even if the disk is mounted (must be given in addition to -e).
r
Write protect the disk.
w
Remove write protection.
p
Password write protect.
x
Password protect
u
Temporarily unprotect the disk until it is ejected. The disk becomes writable, and reverts back to its old state when ejected.
q
Queries the status

anemone [-display host:display.screen] [-visual visual] [-window] [-root] [-delay number] [-arms number] [-finpoints number] [-width number]
DESCRIPTION
Wiggling tentacles.
OPTIONS

-visual visual
Specify which visual to use. Legal values are the name of a visual class, or the id number (decimal or hex) of a specific visual.
-window
Draw on a newly-created window. This is the default.
-root
Draw on the root window.
-delay number
Per-frame delay, in microseconds. Default: 40000 (0.04 seconds.).
-arms number
Arms. 2 – 500. Default: 128.
-finpoints number
Tentacles. 3 – 200. Default: 64.
-withdraw number
Frequency that the arms withdraw. Arms withdraw on randomly generated values between 1 and 11; this value determines the maximum value of that range. So 100 spends a lot of time withdrawn, while 1000,000 tends not to withdraw at all. Default: 1200.
-turnspeed number
How fast it turns. At zero, not at all, all they way up to thousands which are very fast indeed. Default: 50.
-width number
Thickness. 1 – 10. Default: 2.

alsactl is used to control advanced settings for the ALSA soundcard drivers. It supports multiple soundcards. If your card has features that you can’t seem to control from a mixer application, you have come to the right place.

INVOKING

alsactl [options] [store|restore]

Commands

store saves the current driver state for the selected soundcard to the configuration file.

restore loads driver state for the selected soundcard from the configuration file.

If no soundcards are specified, setup for all cards will be saved or loaded.

Options

-h, –help
Help: show available flags and commands.