'My shell script for checking leap year is showing error

#!/bin/bash

echo "Enter the year (YYYY)"
read year

if[ $((year % 4)) -eq 0] 
then
  if[ $((year % 100)) -eq 0] 
    then
    if[ $((year % 400)) -eq 0] 
          then 
        echo "its a leap year"
    else
           echo "its not a leap year"
    fi
  else
  echo "Its not a leap year"
  fi
else
 echo "its not a leap year"

fi

its showing error on 7th line and also on 

[ $((year % 4)) -eq 0]
bashshell


Solution 1:[1]

You've made it too complicated. Use this code to figure leap year:

isleap() { 
   year=$1
   (( !(year % 4) && ( year % 100 || !(year % 400) ) )) &&
      echo "leap year" || echo "not a leap"
}

Test it:

$ isleap 1900
not a leap
$ isleap 2000
leap year
$ isleap 2016
leap year
$ isleap 1800
not a leap
$ isleap 1600
leap year

Solution 2:[2]

You miss some blanks which are nesessary in bash:

echo "Enter the year (YYYY)"
read year

if [ $((year % 4)) -eq 0 ]
then
  if [ $((year % 100)) -eq 0 ]
    then
    if [ $((year % 400)) -eq 0 ]
          then
        echo "its a leap year"
    else
           echo "its not a leap year"
    fi
  else
  echo "Its a leap year"
  fi
else
 echo "its not a leap year"

fi

Solution 3:[3]

Test This Code:

#!/bin/bash

echo "Enter a year to check - "

read y

year=$y 

ans=`expr $year % 4`

if [ $ans -eq 0 ]

then    

    echo "Leap Year"

else

    echo "Not a Leap Year"

fi

Solution 4:[4]

I like one-liners because I do a lot of scripting. Here's an awk solution and test code:

#!/bin/csh -f

set years = "1898 1899 1900 1901 1902 1903 1904 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2016"

foreach year ($years) echo -n "$year " echo $year | awk '{if(($1%4)!=0){ly=0}else{if(($1%400)==0){ly=1}else{if(($1%100)==0){ly=0}else{ly=1}}}} END{if(ly){print "yes"}else{print "no"}}' end

The logic is elsewhere on this page

Solution 5:[5]

You can use this also

if [[ $(( y % 4 )) = 0 && $(( y % 400 )) = 0 || $(( y % 100)) != 0 ]]

or

Leap year

Solution 6:[6]

#!/bin/bash

echo "Enter the year (YYYY)"

read year

if [ $((year%4)) -eq 0 ]

then

if [ $((year%100)) -eq 0 ]

then

if [ $((year%400)) -eq 0 ]

      then

    echo "its a leap year"

else

       echo "its not a leap year"

fi

else

echo "Its a leap year"

fi

else

echo "its not a leap year"

fi

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 anubhava
Solution 2
Solution 3 Mazin Ibrahim
Solution 4 Ed Christiansen
Solution 5 cigien
Solution 6 resh singh

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