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Bash Example Scripts

Computer Architecture​

This script displays a message based on the architecture of the computer:

#!/usr/bin/bash​
architecture="$(uname -m)" # uname gets system information​
​
if [[ "$architecture" == "x86_64" ]]
then​
   echo "Your computer architecture is Intel/AMD x86_64."​
elif [[ "$architecture" == "aarch64" ]]
then​
   echo "Your computer uses the 64-bit Arm architecture."​
else​
  echo "Your computer uses an unrecognized architecture."​
fi

Age Check​

This script checks whether a customer is of legal drinking age in Ontario:

#!/usr/bin/bash​
read -p "Enter the customer's date of birth: " B​
​
# Calculate the time in seconds that the customer turns/tuned 19​
D="$(date -d "$B + 19 years" +%s)"​
 ​
# Get the current time in seconds
NOW="$(date +%s)"​

# Tell the user if the customer is old enough to be served alcohol​
# This tests checks to see if the customer's 19th birthday is
# less than (before) the current date.
if [[ "$D" -lt "$NOW" ]]
then​
    echo "The customer is of legal drinking age in Ontario."​
else​
    echo "The customer is too young to legally drink in Ontario."​
fi

Coinflip​

This script flips a virtual coin:

#!/usr/bin/bash​

COINFLIP=$((RANDOM % 2))​  # % is the modulus operator
if [[ "$COINFLIP" == 0 ]]
then​
    echo "Heads!"​
else​
    echo "Tails"​
fi

The COINFLIP variable is set to the remainder of the division of $RANDOM by 2. Therefore, it will have a random value of 0 or 1.

Cautious File Delete​

This script checks a file, provided as a positional argument (parameter), to ensure that it is a regular file and is writable, and then asks the user if they want to delete it. Note that this script uses the -f (file) test, -w (writeable) test, and combines a number of string tests with the || (OR) operator:

#!/usr/bin/bash​
if `[`"$#" -ne 1`]("$#"_-ne_1 "wikilink")\
then
    echo "$(basename $0): Error: one filename argument must be provided." >&2
    exit 1
fi
F="$1"  # Put the first (and only!) argument value into the variable F
if [[ ! -f "$F" ]​]
then​
    echo "The filename '$F' does not refer to a regular file - skipping."​
elif [[ ! -w "$F" ]​]
then​
    echo "The file '$F' is not writeable (by you) - skipping."​
else​
    read -p "Delete the regular file '$F'? (Y/N): " YESNO​
    if [[ "$YESNO" == "Y" || "$YESNO" == "y" || "$YESNO" == "Yes" ​
           || "$YESNO" == "yes" || "$YESNO" == "YES" ]]​
    then​
        echo "Deleting the file '$F'..."​
        rm "$F"    # We should add some code to check if the rm succeeds or fails​
        echo "...done."​
    else​
        echo "Skipping the file '$F' as requested."​
    fi​
fi