pwd
whoami

pwd - shows current present working directory

whoami - Shows the current use

Declaring Variables:

#!/usr/bin/env bash

NAME="John"
echo "Hello $NAME!"
echo $NAME
echo "$NAME"
echo "${NAME}!"

Functions :

# One Way
myfunc() {
    echo "hello $1"
}
# Second Way
function myfunc() {
    echo "hello $1"
}
# Calling it 

myfunc "John"

# Declaring local variables in Functions
myfunc() {
    local myresult='some value'
    echo $myresult
}

Untitled

Raise Errors :

myfunc() {
  return 1
}
if myfunc; then
  echo "success"
else
  echo "failure"
fi

Defining Arrays :

Fruits=('Apple' 'Banana' 'Orange')

Fruits[0]="Apple"
Fruits[1]="Banana"
Fruits[2]="Orange"

Operations on these Arrays :

Fruits=("${Fruits[@]}" "Watermelon")    # Push
Fruits+=('Watermelon')                  # Also Push
Fruits=( ${Fruits[@]/Ap*/} )            # Remove by regex match
unset Fruits[2]                         # Remove one item
Fruits=("${Fruits[@]}")                 # Duplicate
Fruits=("${Fruits[@]}" "${Veggies[@]}") # Concatenate
lines=(`cat "logfile"`)                 # Read from file
echo ${Fruits[0]}           # Element #0
echo ${Fruits[-1]}          # Last element
echo ${Fruits[@]}           # All elements, space-separated
echo ${#Fruits[@]}          # Number of elements
echo ${#Fruits}             # String length of the 1st element
echo ${#Fruits[3]}          # String length of the Nth element
echo ${Fruits[@]:3:2}       # Range (from position 3, length 2)
echo ${!Fruits[@]}          # Keys of all elements, space-separated

Iteration over an Array :