Spring Switzerland GmbH 2000 - Manual (Page 12)

Manipulation of text files
diff compares two files and reports the differences.
grep search file for pattern (regular expression).
sort sorts textfiles.
head prints first 10 lines of file.
tail prints (surprise) last 10 lines of file.
a2ps “pretty-prints” ASCII files on a printer – actually a PostScript file i generated and sent to a printer.
wc counts lines/words/letters in a file.
Redirection of input or output
To redirect the input or output for a program invoked by a command you use < and > . For example to
redirect the output from a directory listing (command ls ) to outputfile, you would do the following:
ls > outputfile. To redirect the input from a file, you use <
Pipelines
Pipelines allow you to let the output of one program be used as input to another program. This is done
in a command line containing several commands separated by bar characters “
| ”. Each bar denotes a
pipeline which “pipes” the output of the command to the left of the bar to the input of the command
to the right of the bar.
Example: let’s assume that you have created a program that outputs textlines, and you want to see the
first 15 lines containing the word “helloworld”, you would execute the following:
myprogram |
grep helloworld | head -n 15
11 Desktop enviroments in the data bars
The graphics subsystem in Linux is an implementation of The X Window System or just X for short. It
implements the basic graphic and windowing primitives and it is totally network transparent (unlike
the graphics system of another well-known operating system). This means that you can run an entire
session, or just a single application on any other computer in the data bar system from a PC in the data
bar.
A window manager works on top of the graphics subsystem and it implements the lay-out of windows
(borders, buttons, etc.), how to move windows around, how to use menus, and so on. The term desktop
enviroment covers X, a windowmanager and a suite of utilites, configuration programs, games, editors
and so on.
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