script_listing

#!/bin/more
======================================
SCRIPT NAME: arithmetic_operators.sh
======================================
#!/bin/bash
# This script is intended to show the usage of
# arithmetic operations

# Addition
expr 2 + 2

# Subtration
expr 2 - 2

# Division
expr 2 / 2

# Multiplication - * must be escaped with \
expr 2 \* 2

# Modulus
expr 15 % 2

# Command substitution
echo `expr 15 \* 2`

# Set expression to variable
MY_VARIABLE=$(expr 10 \* 20)
echo $MY_VARIABLE
======================================
SCRIPT NAME: arrays.sh
======================================
#!/bin/bash
# This script intends to show the usage of arrays in bash

MYARRAY=("First" "Second" "Third")
# will only echo 0 index value of array
echo $MYARRAY

# Enclose variable in brackets with index position to echo
echo ${MYARRAY[0]}
echo ${MYARRAY[1]}
echo ${MYARRAY[2]}

# Echo all items in array
echo ${MYARRAY[*]}

MYARRAY[3]="Fourth"
echo ${MYARRAY[*]}

# Comma delimited arrays are bad - bash treats the array elements
# as a single array element
NEWARRAY=("First","Second","Third")
echo $NEWARRAY
echo ${NEWARRAY[0]}

# Simple array list and loop for display
SERVERLIST=("websrv01" "websrv02" "websrv03" "websrv04")
COUNT=0
for INDEX in ${SERVERLIST[@]}; do
    echo "Processing Server: ${SERVERLIST[COUNT]}"
    COUNT="$(expr $COUNT + 1)"
done
======================================
SCRIPT NAME: case_statement.sh
======================================
#!/bin/bash
# This script is intended to show the usage of a case statement

clear

echo "  MAIN MENU"
echo "==============="
echo "1) Choice One"
echo "2) Choice Two"
echo "3) Choice Three"
echo ""
echo "Enter choice:"
read MENUCHOICE

case $MENUCHOICE in
    1)
        echo "You chose option #1";;
    2)
        echo "You chose option #2";;
    3)
        echo "You chose option #3";;
    *)
        echo "You chose poorly";;
esac
======================================
SCRIPT NAME: checkargs1.sh
======================================
#!/bin/bash
# This script is intended to show how to check CLI parameters

if [ "$#" != "3" ]; then
    echo "USAGE: checkargs.sh [param1] [param2] [param3]"
    exit 300
fi

echo "I live! I got what I needed"
======================================
SCRIPT NAME: checkargs2.sh
======================================
#!/bin/bash

# If statement on one line to check CLI arguments passed through
: ${3?"Usage: $1 ARGUMENT $2 ARGUMENT $3 ARGUMENT"}

echo "I got all three!"
======================================
SCRIPT NAME: cli_vars.sh
======================================
#!/bin/bash
# This script is intended to show how to pass arguments
# from the command-line to this script

USERNAME=$1
PASSWORD=$2
echo "The following username is $USERNAME and password is $PASSWORD"
======================================
SCRIPT NAME: cmd_substitution.sh
======================================
#!/bin/bash
# This script is intended to show how to do simple substitution

# Allows to expand aliases in subshells
shopt -s expand_aliases

alias TODAY="date"
alias UFILES="find /home -user david.coy"

TODAYDATE=`date`
USERFILES=`find /home -user david.coy` # Will not output anything on Darwin

echo "$TODAYDAY"
echo "$USERFILES"

A=`TODAY`
B=`UFILES`

echo "With alias, TODAY is:"
echo "With alias, UFILES is:"
======================================
SCRIPT NAME: comments.sh
======================================
#!/bin/bash
# This line is intended to be used as a general description
# of the script and anything it does

echo '####################################'
echo "This line above is not commented out" # This is commented out
======================================
SCRIPT NAME: dev_null_usage.sh
======================================
#!/bin/bash
# This script intends to show the usage
# of /dev/null

# Redirect to /dev/null
echo "This is displaying on the console."

echo "This is going into the black hole." >> /dev/null

# Redirect STDOUT to /dev/null
echo "This is standard out" 1> /dev/null

# Redirect STDERR to /dev/null
echo "This is standard error" 2> /dev/null

# Redirect STDOUT and STDERR to /dev/null
echo "This will redirect STDOUT and STDERR" > /dev/null 2>&1
======================================
SCRIPT NAME: document_generator.sh
======================================
#!/bin/bash
# This script is intended to show how to build a document generator

DOCFILE="script_listing"

echo "#!/bin/more" > "$DOCFILE"

ls *.sh > templisting.txt

while IFS= read -r FILENAME; do
    if [ -f "$FILENAME" ]; then
        echo "======================================" >> "$DOCFILE"
        echo "SCRIPT NAME: $FILENAME" >> "$DOCFILE"
        echo "======================================" >> "$DOCFILE"
        echo ""
        echo "$(cat $FILENAME)" >> "$DOCFILE"
    fi
done < templisting.txt

chmod 755 "$DOCFILE"

rm templisting.txt
======================================
SCRIPT NAME: env.sh
======================================
#!/bin/bash

echo "This script will give us environment information"
echo ""
echo "================================================"
echo ""
echo "Hello Username: $USER"
echo ""
echo "Your home directory is: $HOME"
echo "Your shell is: $SHELL"
echo "Your language is set to: $LANG"
echo "Your system is: $_system_name"
echo "================================================"
echo ""
======================================
SCRIPT NAME: env_var_example.sh
======================================
#!/bin/bash
# This exercise is intended to display the environment variables

echo $USER
echo $HOME
echo $HISTCONTROL
echo $TERM
======================================
SCRIPT NAME: error_handling.sh
======================================
#!/bin/bash
# This script intends to show the usage of error handling with exit

echo "Change to a directory and list the contents"
DIRECTORY=$1

cd $DIRECTORY 2>/dev/null

if [ "$?" = "0" ]; then
    echo "We can change into the directory $DIRECTORY, and here are the contents"
    echo "$(ls -alh)"
else
    echo "Cannot change directories, exiting with an error no listing"
    exit 111
fi
======================================
SCRIPT NAME: errors.sh
======================================
#!/bin/bash
# This is to show exit status types
# It will use `echo $?` to display exit status
# 0 is success, non-zero is failure
# `set -e` wille exit the script once an error occurs
set -e

expr 1 + 5
echo $?

rm test.txt
echo $?

expr 10 + 10
echo $?
======================================
SCRIPT NAME: execution_operator.sh
======================================
#!/bin/bash
# This script is intended to show the usage of execution operators in bash

echo "Enter a number between 1 and 5: "
read VALUE

if [ "$VALUE" -eq "1" ] || [ "$VALUE" -eq "3" ] || [ "$VALUE" -eq "5" ]; then
    echo "You entered an odd value of $VALUE."
else
    echo "You entered a value of $VALUE."
fi
======================================
SCRIPT NAME: file_descript.sh
======================================
#!/bin/bash
# This script intends to show the usage of assigning descriptors to a file
# for reference -- read/write to file using file descriptor

echo "Enter a filename to read: "
read FILENAME

# '>' denotes 'write', '<' denotes 'read', '<>' denotes 'read/write'
exec 5<>$FILENAME

while read -r FRUIT; do
    echo "Fruit: $FRUIT"
done <&5

echo "This file was read on: $(date) by $USER" >&5

# Close out '5' connections
exec 5>&-
======================================
SCRIPT NAME: for_loop.sh
======================================
#!/bin/bash
# This script is intended to show how a for-loop works in bash

echo "List all of the shell script contents of the directory"

SHELLSCRIPTS=$(ls *.sh)

for i in "$SHELLSCRIPTS"; do
    DISPLAY="$(cat $i)"
    echo "File: $SCRIPT - Contents: $DISPLAY"
done
======================================
SCRIPT NAME: function_exit_return.sh
======================================
#!/bin/bash
# This script intends to show the usage of return and exit in functions

# Global variable declaration
YES=0
NO=1
FIRST=$1
SECOND=$2
THIRD=$3

# =========================== #
# Function definition - start #
# =========================== #

# Check command line params passed in
funcCheckParams() {
  # Did we get three?
  if [ ! -z "$THIRD" ]; then
      echo "We got three parameters."
      return $YES
  else
      echo "We did not get three parameters."
      return $NO
  fi
}

# =========================== #
# Function definitions - stop #
# =========================== #

# Script - start

funcCheckParams
RETURN_VALS=$? # 0 or 1

# Did we get 3 or not?
if [ "$RETURN_VALS" -eq "$YES" ]; then
    echo "We received three params and they are: "
    echo "Param 1: $FIRST"
    echo "Param 2: $SECOND"
    echo "Param 3: $THIRD"
    echo ""
else
    echo "Usage: function_exit_return.sh [param1] [param2] [param3]"
    exit 1
fi

# Script -stop
======================================
SCRIPT NAME: function_organization.sh
======================================
#!/bin/bash
# This script intends to show how to organize scripts to use functions


# Global or script variables
CMDLINE=$1

echo "The script has started!"

# # # # # # # # # # # # # # # # #
# Function definitions -- start #
# # # # # # # # # # # # # # # # #

# Displays a message
funcExample() {
  echo "This is an example function."
}

# Display another message
funcExample2(){
  echo "This is another example"
}

# Beginning the script
echo "This is the start..."

funcExample
funcExample2
======================================
SCRIPT NAME: function_var_scope.sh
======================================
#!/bin/bash
# This script intends to show variable scope in functions

# Global variable declaration
GLOBALVAR="Globally Visible"

# Function definiton start

# Sample function for function variable scope
funcExample() {
  # local variable to the function
  LOCALVAR="Locally Visible"
  echo "From within the function, the variable is $LOCALVAR"
}

# Function definitions - stopped

# Script start

clear
echo "This step happens first..."
echo ""
echo "GLOBAL variable = $GLOBALVAR (before the function call)"
echo "LOCALVAR variable = $LOCALVAR (before the function call)"
echo ""
echo ""
echo "Calling the function - funcExample()"
echo ""

funcExample

echo ""
echo "The function has been called..."
echo ""
echo "GLOBAL variable = $GLOBALVAR (after the function call)"
echo "LOCALVAR variable = $LOCALVAR (after the function call)"
echo ""
echo "Script end"
======================================
SCRIPT NAME: functions.sh
======================================
#!/bin/bash
# This script is intended to show functions with bash

echo "Hello there! -- outside the function"

functionExample () {
  echo "Hello there -- inside the function"
}

singleLineFunction(){ echo "This is a single line function"; }

functionExample
singleLineFunction
======================================
SCRIPT NAME: functions_parameters.sh
======================================
#!/bin/bash
# This script is intended to show functions with parameters

# Global variable declaration
USERNAME=$1

# Function definitions - start

# Calculate age in days
funcAgeInDays() {
  echo "Hello $USERNAME, you are $1 years old."
  echo "That makes you approximately $(expr $1 \* 365) days old."
}

# Function defintions - stop

# Script start
clear
echo "Enter your age: "
read USERAGE

# Calculate the number of days
funcAgeInDays $USERAGE
======================================
SCRIPT NAME: if_statement.sh
======================================
#!/bin/bash
# This script is intended to show the usage of the 'if'
# conditional statement

echo "================"
echo "Guess the number"
echo "================"
echo ""
echo "Enter a number between 1 and 5: "
read GUESS

if [ $GUESS -eq 3 ]
then
    echo "You guessed the correct number!"
fi

if [ $GUESS -eq 4 ]
then
    echo "You guessed the correct number!"
fi
======================================
SCRIPT NAME: if_then_else.sh
======================================
#!/bin/bash
# This script is intended to use conditional statements- if/then/else
# and nested if statements

clear

echo "Enter a number between 1 and 3:"
read VALUE

if [ "$VALUE" -eq "1" ] 2>/dev/null; then
    echo "You entered #1."
elif [ "$VALUE" -eq "2" ] 2>/dev/null; then
    echo "You entered #2."
elif [ "$VALUE" -eq "3" ] 2>/dev/null; then
    echo "You entered #3."
else
    echo "You didn't enter a number between 1 and 3."
fi
======================================
SCRIPT NAME: ifs_delimiting.sh
======================================
#!/bin/bash
# This script is intended to show how to process a file with delimiters
# IFS = Internal Field Separator

echo "Enter filename to parse: "
read FILENAME

echo "Enter the delimiter: "
read DELIM

IFS=$DELIM

while read -r CPU MEMORY DISK; do
    echo "CPU: $CPU"
    echo "Memory: $MEMORY"
    echo "Disk: $DISK"
done <"$FILENAME"

unset IFS
======================================
SCRIPT NAME: implicit_explicit_vars.sh
======================================
#!/bin/bash
# This script is intended to show the usage of
# implicit and explicit variable definition

# Implicitly declared integer variable
MYVAR=5
echo $MYVAR
echo "$(expr $MYVAR + 5)"

# How to determine 'what' a variable is
declare -p MYVAR # declare -- MYVAR="5"

MYVAR2="Name"
echo $MYVAR2

# Set variable as integer with -i
declare -i NEWVAR=10
echo $NEWVAR

# Declare read-only variable
declare -r READONLY="This is a string we cannot overwrite"
echo $READONLY
READONLY="This is me trying to redeclare the read-only variable"
======================================
SCRIPT NAME: info_box.sh
======================================
#!/bin/bash
# This script is intended to show the usage of the info box with ncurses

# Global variable/default value declaration
INFOBOX=${INFOBOX=dialog}
TITLE="Default"
MESSAGE="Something to say"
XCOORD=10
YCOORD=20

# Function declarations - start

# Display the info box and message
funcDisplayInfoBox() {
    $INFOBOX -- title "$1" --infobox "$2" "$3" "$4"
    sleep "$5"
}

# Function declarations - stop

# Script start

if [ "$1" == "shutdown" ]; then
    funcDisplayInfoBox "WARNING!" "We are SHUTTING DOWN the system..." "11" "21" "5"
    echo "Shutting down!"
else
    funcDisplayInfoBox "Information..." "You are not doing anything fun..." "11" "21" "5"
    echo "Not doing anything..."
fi

# Script end
======================================
SCRIPT NAME: input_box.sh
======================================
#!/bin/bash
# This script intends to show the usage of the input box in bash scripts

# Global variable/default value declaration
INPUTBOX=${INPUTBOX=dialog}
TITLE="Defualt"
MESSAGE="Something to display"
XCOORD=10
YCOORD=20

# ============================= #
# Function declaration -- start #
# ============================= #

# Display input box
funcDisplayInputBox() {
    $INPUTBOX --title "$1" --inputbox "$2" "$3" "$4" 2>tmpfile.txt
}

# =========================== #
# Function declaration -- end #
# =========================== #

# Script start
funcDisplayInputBox "Display filename" "Which file in the current directory do you want to display?" "10" "20"

if [ "$(cat tmpfile.txt)" != "" ]; then
    echo "$(cat tmpfile.txt)"
else
    echo "Nothing to do."
fi

# Script end
======================================
SCRIPT NAME: menu_system.sh
======================================
#!/bin/bash
# This script intends to show how to build a menu system in bash scripts

# Global variable/default value declaration
MENUBOX=${MENUBOX=dialog}


# ============================= #
# Function declaration -- start #
# ============================= #

# Function to display a simple menu
funcDisplayMenuBox() {
    $MENUBOX --title "[ M A I N  M E N U ]" --menu "Use UP/DOWN arrows to move and select or the number of your choice and ENTER/RETURN" 15 45 4 1 "Display 'Hello world'" 2 "Display 'Goodbye world'" 3 "Display 'Nothing'" X "Exit" 2>choice.txt
}

# =========================== #
# Function declaration -- end #
# =========================== #

# Script start
funcDisplayMenuBox

case "$(cat choice.txt)" in
    1) echo "Hello world!";;
    2) echo "Goodbye world!";;
    3) echo "Nothing";;
    X) echo "Exit";;
esac

# Script end
======================================
SCRIPT NAME: message_box.sh
======================================
#!/bin/bash
# This script is intended to show a message box for confirmation in bash scripts

# Global variable/default value declaration
MSGBOX=${MSGBOX=dialog}
TITLE="Default"
MESSAGE="Some message"
XCOORD=10
YCOORD=20

# ============================ #
# Function declaration - start #
# ============================ #

# Dispaly the message box with message
funcDisplayMessageBox() {
    $MSGBOX --title "$1" --msgbox "$2" "$3" "$4"
}

# ========================== #
# Function declaration - end #
# ========================== #

# Script - start
if [ "$1" == "shutdown" ]; then
    funcDisplayMessageBox "WARNING!" "Please press OK when you are ready to shut down the system" "10" "20"
    echo "Shutting down NOW!"
else
    funcDisplayMessageBox "Boring..." "you are not asking for anything fun..." "10" "20"
    echo "Not doing anything, back to regular scripting..."
fi
# Script - end
======================================
SCRIPT NAME: nested_functions.sh
======================================
#!/bin/bash
# This script is intended to show the usages of nested functions

# Global Variable
GENDER=$1

# Function definitions - start

# Create a human being
funcHuman() {
  ARMS=2
  LEGS=2

  echo "A human has $ARMS arms and $LEGS legs - but what gender are we?"

  funcMale() {
    BEARD=1

    echo "This man has $ARMS arms and $LEGS legs, with $BEARD beard."
    echo ""
  }

  funcFemale() {
    BEARD=0

    echo "This woman has $ARMS arms and $LEGS legs, with $BEARD beard."
    echo ""
  }
}

# Function definitions - stop

# Script start
clear
echo "Determining the characteristics of the gender $GENDER"
echo ""

if [ "$GENDER" == "male" ]; then
    funcHuman
    funcMale
else
    funcHuman
    funcFemale
fi
======================================
SCRIPT NAME: overriding_events.sh
======================================
#!/bin/bash
# This script is intended to show how to override events with bash scripting
# by overriding/trapping the system exit and execute a custom function

# Global variable/default value declaration
TMPFILE="tempfile1.txt"
TMPFILE2="tempfile2.txt"

trap 'funcMyExit' EXIT

# Function declaration -- start
# Run this exit instead of default exit when called
funcMyExit() {
    echo "Exit intercepted..."
    echo "Cleaning up temp files..."
    rm -rf tempfile*.txt
    exit 255
}

# Function declaration -- end

# Script -- start

echo "Write something to tempfile for later use..." > $TMPFILE
echo "Write something to tempfile 2 for later use..." > $TMPFILE2

echo "Trying to copy the indicated file before processing..."
cp -rf $1 newFile.txt 2>/dev/null

if [ "$?" == "0" ]; then
    echo "Everything worked out fine."
else
    echo "Looks like it did not work out as intended."
    exit 1
fi

# Script -- end
======================================
SCRIPT NAME: read_sample.sh
======================================
#!/bin/bash
# This script is intended to show the usage of the `read` command

echo "Enter your First Name: "
read FIRSTNAME
echo "Enter your Last Name: "
read LASTNAME
echo "Enter your age: "
read USERAGE
echo ""

echo "Your full name is: $FIRSTNAME $LASTNAME"
echo "In ten years, you will be $(expr $USERAGE + 10) years old."
======================================
SCRIPT NAME: reading_files.sh
======================================
#!/bin/bash
# This script is intended to show the usage of reading files

echo "Enter a filename to read: "

#Debugging start
set -x
read FILENAME

while read -r FRUIT; do
    set +x

    echo "Fruit: $FRUIT"

    set -x
done < "$FILENAME"

# Stop debugging
set +x
======================================
SCRIPT NAME: shell_expansion.sh
======================================
#!/bin/bash
# This script is intended to show the usage of shell expansion

echo sh{ort,oot,ot}

echo st{il,al}l

# Echo current directory - similar to `pwd`
echo ~+

# Echo old `pwd` direcotry
echo ~-

# Echo a multiplication expression - does not need to be escaped
echo "$[ 2 * 2 ]"
======================================
SCRIPT NAME: special_chars.sh
======================================
#!/bin/bash
# This script is intended to show how to use
# special characters in a bash script

# Using double quotes
echo "\$MY_VARIABLE"

# Using single quotes
echo '$MY_VARIABLE'

# Using quotes in a string
echo "\"\""
======================================
SCRIPT NAME: testfile.sh
======================================
#!/bin/bash
# Tests for existence of indicated filename

FILENAME=$1
echo "Testing for the existence of a file called $FILENAME"

if [ -a $FILENAME ]
then
    echo "File $FILENAME does exist."
fi

if [ ! -a $FILENAME ]
then
    echo "File $FILENAME does not exist."
fi

echo ""
# Testing multiple expressions in single if statement
FILENAME2=$2
echo "Testing for file $FILENAME2 and readability."
if [ -f $FILENAME2 ] && [ -r $FILENAME2 ]
then
    echo "File $FILENAME2 exists and is readable."
fi


if [ ! -f $FILENAME2 ]
then
    echo "File $FILENAME2 does not exist."
fi
======================================
SCRIPT NAME: trap_sig.sh
======================================
#!/bin/bash
# This script intends to show the usage of 'trap' and signals

clear

trap 'echo " - Welp, sorry bro, press Q or q!"' SIGINT SIGTERM SIGTSTP

while [ $"CHOICE" != "Q" ] && [ "$CHOICE" != "q" ]; do
    echo "MAIN MENU"
    echo "========="
    echo "1) Choice One"
    echo "2) Choice Two"
    echo "3) Choice Three"
    echo "Q) Quit/Exit"
    echo ""
    read CHOICE

    clear
done
======================================
SCRIPT NAME: while_loop.sh
======================================
#!/bin/bash
# This script is intended to show the usage of a while-loop

echo "Enter the number of times to display the 'hello world' message:"
read DISPLAYNUMBER

COUNT=1

while [ $COUNT -le $DISPLAYNUMBER ]; do
    echo "Hello world - $COUNT"
    COUNT="$(expr $COUNT + 1)"
done