Shell Programming and Scripting

 
#!/bin/bash
echo -n "Enter: "
read num
 if(($(echo ${#num}) == 0 ))
   then
    echo No arguments passed.Try again
 elif
    rem=$(echo $num | tr -d [0-9])
    lenght=$(echo ${#rem})
      if(( $lenght > 0))
        then
       echo "$num is not a number"
      else
       echo "$num is a number"
       fi
  else
    echo "Good job"      
    fi

#!/bin/bash

echo -n "Enter: "
read num

if(( ${#num}) == 0 ))
then
   echo "No arguments passed.Try again"
#elif #elif what? should be else
else
   if(( $(echo "$num" | tr -d [0-9]) > 0))
   then
      echo "$num is not a number"
   else
      echo "$num is a number"
   fi
#else #shouln't be here
   echo "Good job"
fi

#!/usr/bin/bash or ksh or ...
echo -n "Enter: "
read num

[ "$num" = "" ] && "No arguments passed.Try again" && exit 1

# replace numbers using nothing
other=${num//[0-9]/} # remove numbers using builtin replace = like tr -d "[0-9]"

# if something left, those are not numers
[ "$other" != "" ] && echo "$num is not a number" && exit 2

echo "Good job"

 
#!/bin/bash
echo -n "Enter: "
read num
check($num)
function check($num)
{
 if(($(echo ${#num}) == 0 ))
   then
    echo No arguments passed.Try again
 else
    rem=$(echo $num | tr -d [0-9])
    lenght=$(echo ${#rem})
      if(( $lenght > 0))
        then
       echo "$num is not a number"
      else
       echo "$num is a number"
       fi
 fi
}