UNIX for Dummies Questions & Answers

hi guys, im learning so be gentle...

i'm wanting to write a script to read in a customer number.

in order that the code is robust i want to check

1) the length of the value entered (4 characters)
2) that all characters entered are numeric between the values 1 to 3
3) that a value is entered

could anyone give me a few pointers to the commans/systax i will need to use for each check?

also any idea if any of them can be combined?

any pointers welcome...

thanks

skinnygav

If have prompted the customer for their number and read it in thus:

Code:

read -p "Please enter you customer number: " RESP

I'll leave some else who can test for digits more elegantly than I.

Then to check they have entered anything at all you can do:

Code:

if [ -n "${RESP}" ]; then
  echo "You answered ${RESP}."
fi

or

Code:

if [ -z "${RESP}" ]; then
  echo "You have not entered anything, please try again."
fi

To check how many characters have been entered do:

Code:

LENGTH=`echo ${RESP} | wc -c`

if [ ${LENGTH} -ge 10 ]; then
  echo "The number entered is too long."
fi

if [ ${LENGTH} -le 8 ]; then
  echo "The number entered is too short."
fi

Note that wc -c counts the new line character, so adds one to the length you are expecting.