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GNU Compiler Collection (GCC)
and GNU C compiler (gcc)
• tools used to compile programs in Linux
Hello World! program compilation
in C
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#include <stdio.h>
int main()
{
printf("hello world!\n");
}
PERL, Python, and bash—script
interpreters in Linux
• Python is for rapid GUI development
• PERL is for complex jobs and Web pages
• bash is for everyday, general-purpose
scripting.
Control structures used to develop
scripting logic
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If...Then...Else statements
Case statements
For loops
While loops
• table on page 907
BASH Scripting
• Shell scripting provides a way to automate
everyday tasks into much simpler commands.
– For example, to add 200 users would require
running the useradd command 200 times.
• The first line of a script identifies the shell or
interpreter used to run this script.
– Linux uses BASH as the default shell so
#! /bin/bash is the first line of BASH scripts.
• Any line with a # sign is a comment line.
– Use comments to document what a script is
doing.
• BASH scripting is basically taking several
commands into one file in the sequence
you wish them executed.
• The read statement reads the value of a
variable from stdin (standard input).
– It fetches input from the keyboard or a source
redirected to it.
• read a will read a single value from stdin
• read a b c will read multiple values on a single line from
stdin.
• You don’t have to declare variables, just use
them
– VAR1 = 2
– VAR2 = “Hello, World”
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• Any arguments to the script are numbered
$1, $2, $3, etc and used in the script by
their numbers
• The echo line displays values.
– It can display text: echo “Hello, world”
– It can display the contents of a variable: echo
VAR1
pg905
Lab5.2
Pg911
Pg 929
Lab 5.4
pg919 ex.
Pg 921
Lab 5.5
The Read command
• the Read command will be used with the
While loop to take input from a file. This
requires the use of the standard input
redirector.
Pg 956