Shell Programming and Scripting

#!/bin/bash

blah=1
echo -n "Press a key from 3-7."
read -n 1 -s blah
if [ $blah > 3 ]
then
        if [ $blah < 7 ]
        then
        echo "You entered $blah, that works."
        else
        echo "You entered $blah, that's too high."
        fi
else
echo "You entered $blah, that's too low."
fi
exit

$ 
$ cat -n testkey.sh
     1  #!/bin/bash
     2
     3  echo -n "Press a key from 3-7 : "
     4  read CHR
     5  echo "You entered $CHR"
     6
     7  # Using case statement
     8  case "$CHR" in
     9    [3-7])  echo "It's in the range [3,7]";;
    10    *)      echo "It's NOT in the range [3,7]";;
    11  esac
    12
    13  # Using if branch
    14  if (( $CHR >= 3 && $CHR <= 7 ))
    15  then
    16    echo "Once again, it's in the range [3,7]";
    17  else
    18    echo "Once again, it's NOT in the range [3,7]";
    19  fi
    20
$ 
$ ./testkey.sh
Press a key from 3-7 : 2
You entered 2
It's NOT in the range [3,7]
Once again, it's NOT in the range [3,7]
$ 
$ ./testkey.sh
Press a key from 3-7 : X
You entered X
It's NOT in the range [3,7]
Once again, it's NOT in the range [3,7]
$ 
$ ./testkey.sh
Press a key from 3-7 : 5
You entered 5
It's in the range [3,7]
Once again, it's in the range [3,7]
$ 
$

if [ $blah -ge 3 -a $blah -le 7 ]
then
  echo "You entered $blah, that works."
elif [ $blah -lt 3 ]
then
  echo "You entered $blah, that's too low."
elif [ $blah -gt 7 ]
then
  echo "You entered $blah, that's too high."
fi