Bash examples

bash builtins

if command

Greetings

#!/bin/bash
#Uncomment HOUR=`date +%H` when using for real
#HOUR=`date +%H`
#
#HOUR=$1 only for testing purposes.....
HOUR=$1
if test $HOUR -le 7
  then
    echo "You are early go home"
  else if test $HOUR -le 8
         then
           echo "You are early"
         else if test $HOUR -lt 12
                then
                  echo "Good morning, Vietnam"
                else if test $HOUR -lt 16
                       then
                         echo "Good evening"
                     fi
              fi
       fi
fi

while

count example

#!/bin/bash
COU=1
while test $COU -lt 10000
do
  echo -en "COU = $COU\r"
  COU=`expr $COU + 1`
done

case

secret password example

#!/bin/bash
# Read the username from the terminal
echo -en "Enter username: "
read USERNAME
# Read the password from the terminal not echoing the characters
echo -en "Enter password: "
stty -echo
read PASSWORD
stty echo
# Find the username in the case and check password
case $USERNAME in
  john|John) if test $PASSWORD = "banana"
               then
                echo "Access granted"
               else
                echo "Access denied...."
                exit
             fi
           ;;
  eve|Eve) if test $PASSWORD = "apple"
               then
                echo "Access granted"
               else
                echo "Access denied...."
                exit
             fi
           ;;
  *)       echo "Access denied...."
           exit
           ;;
esac
echo "The secret information is 198273"