Shell Programming and Scripting

 
function check()
{
 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
}

$ cat check.sh
#!/bin/bash

function check()
{
 echo "num_args = $#"

 for myarg in "$@"
 do
    echo "$myarg"
 done
}

check 1 2

exit

$ ./check.sh  
num_args = 2
1
2

#!/bin/bash
function check()
{
 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
}

echo -n "Enter: "
read fnum
let num=fnum  
check "$num"  
echo -n "Enter: "
read snum
let num=snum  
check "$num"

#!/usr/bin/ksh or bash or dash or ...
####
check()
{  
   # function args are just like command line args - you call function as command
   # return in function works same way as exit in script
   [ $# -lt 1 ] && echo "No arguments passed.Try again" >&2 && return 1

   for num in $@
   do
       other=${num//[0-9]/} # remove numbers = like tr -d "[0-9]"

       [ "$other" != "" ] && echo "$num is not a number" >&2 && return 2
       echo "$num is number"
   done
}   

#####MAIN####
echo -n "Enter: "
read num1
check $num1
stat=$?
echo $stat

echo "________________"
echo -n "Enter: "
read num2
check $num2
stat=$?
echo $stat
echo "_________________"
check $num1 $num2

myFunction arg1 arg2 arg3

echo "$1" "$2" "$3"