Script Unix (Not equal to a string) - unix

Question

I wrote the following code :
echo "Choose between the following options:"
echo "1 - Create a new file"
echo "2 - Write in an existing file"
echo "3 - Change the path of a file"
echo "4 - Display a file"
echo "5 - Exit"
read number
while [ $number -ne 1 -o $number -ne 2 -o $number -ne 3 -o $number -ne 4 -o $number -ne 5 ]
do
echo "Enter a number between 1 and 5"
read number
done
if [ $number -eq 1 ]; then
echo "Enter a folder name"
read name
while [ -e $name ]
do
echo "The file name already exists enter a new name:"
read name
done
touch $name
fi
if [ $number -eq 2 ]; then
echo "Enter the folder name you want to edit :"
read name
while [ ! -f $name ]
do
echo "The file you are looking does not exist. Enter another file name :"
read name
done
echo "Enter what you want to put in the file :"
read input
echo $input >> $name
fi
if [ $number -eq 3 ]; then
echo "Enter the folder name :"
read name
while [ ! -f $name ]
do
echo "The file you are looking does not exist. Enter another file name :"
read name
done
if [ $number -eq 4 ]; then
echo "Enter the folder name you want to see :"
read name
while [ ! -f $name ]
do
echo "The file you are looking does not exist. Enter another file name :"
read name
done
cat $name
fi
if [ $number -eq 5 ]; then
exit 0
fi
The code works just fine, but on the first condition :
while [ $number -ne 1 -o $number -ne 2 -o $number -ne 3 -o $number -ne 4 -o $number -ne 5 ]
I would like it to work to whatever number or string I put.
For example, if I put hello the program will crash.
Can someone tell me what should my first condition be?
Thank you for your help. And forgive me if my question is not in the rules of the forum (I just subscribed).

Answer 1

Your script says:
while [ $number -ne 1 -o $number -ne 2 -o $number -ne 3 -o $number -ne 4 -o $number -ne 5 ]
So, if $number is 1, it's not equal to 2. And if it's 2, it's not equal to 1. This will always evaluate as true, so you'll never exit the loop.
A variety of options exist that will be compatible with a numeric value and still gracefully handle non-numeric input. The following uses a basic regular expression to determine whether input is a digit from 1 to 5:
while read number && ! expr "$number" : '[1-5]$' >/dev/null; do
echo "Try again" >&2
done
You would probably be better off, though, using a case statement:
while read number; do
case "$number" in
1) function_1 ;;
2) function_2 ;;
... etc
*) echo "Invalid input, please try again." >&2; continue ;;
esac
break
done
The case statement is a more graceful way of expressing what might otherwise be achieved using if..elif..elif..fi:
while read number && ! expr "$number" : '[1-5]$' >/dev/null; do
echo "Try again" >&2
done
if [ "$number" = 1 ]; then
: do_something
elif [ "$number" = 2 ]; then
: do_something
elif [ "$number" = 3 ]; then
: do_something
elif [ "$number" = 4 ]; then
: do_something
elif [ "$number" = 5 ]; then
: do_something
else
echo "What am I doing?" >&2
fi
While this construct technically works, it's inelegant and harder to read. Much better to put your functionality into functions which get called from a case statement.
Note that it's always a good idea to quote your variables within a script like this. Do you know what happens with unquoted variables? If not, then quote your variables. :)

Answer 2

I would strongly suggest structuring your code with a case statement:
case $number in
1) code_for_1;;
2) code_for_2;;
...
*) echo "Invalid number" >&2;;
esac
If you wish to repeat (I would actually recommend taking the number as a command line argument instead of reading from stdin and aborting on an error), you could simply do:
while read number; do
case $number in
...
*) echo 'Invalid number' >&2; continue;;
esac
break
done
And write code_for_{1,2,3,4,5} as functions to factor out the logic. For example:
create_file() {
echo "Enter a file name"
while read name; do
if test -e "$name"; then
echo "The file $name already exists enter a new name" >&2
continue
fi
touch "$name"
break
done
}
while read number; do
case $number in
1) create_file;;
...
*) echo 'Invalid number' >&2; continue;;
esac
break
done