GNU Compiler Collection (GCC) and GNU C compiler (gcc) tools used to compile programs in Linux.
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Transcript of GNU Compiler Collection (GCC) and GNU C compiler (gcc) tools used to compile programs in Linux.
Hello World! program compilation in C
• #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
• 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”
•
• 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