Simple Bash Scripting

Presented by Died R. June 21, 2019

Sequence, selection and Iteration: https://en.wikipedia.org/wiki/Structured_programming#Theoretical_foundation

• Sequence
  • Ordered statements
    • a = b * 3
    • print “stuff”
    • foo = sin(3)
      
• Selection
  • Choose one or another set of statements
    • if i = 7 then 
      
      • do something
    • else
      • do something else or perhaps nothing
        
• Iteration
  • Do a set of statements repeatedly
    • while i > 92 do things :
      

---

#! /bin/bash
# Structured programming
## https://en.wikipedia.org/wiki/Structured_programming#Theoretical_foundation#! /bin/bash
# sequence

a=5
b=3
echo $a
echo $b

echo $((a + b))

declare -i c;
c=”5 + 4″
echo “$c”
c=$c+1
echo “$c”

## parameters

echo “$1” “$2”
echo ———————–

#! /bin/bash 
# selection
## about [

if [ “$1” = ‘foo’ ]; then
  echo you have foo
else
  echo you are fooless
  echo but you have “$1” and “$2”
fi

if [ -e “$2” ]; then
  echo the file “$2” exists
else
  echo the file “$2” does not exist here.
fi
echo ———————————–

#! /usr/bin/env bash
# iteration
## about let  https://www.computerhope.com/unix/bash/let.htm

n=0
m=$1

while [ $n -lt “$m” ]; do
  echo $n
  let n=n+1
done