Shell Programming and Scripting

Environment: Sun UNIX

Language: Bourne Shell

Problem:
I am writing a script that allows user to key in a directory. Example: /root/tmp.

Since the user can key in anything he/she wants, I need to validate to make sure that he/she does not key in anything funny i.e. #@!*&^$><,."';:}[]+=)(|\%~`

Only "/", "-", "_", alphabet and numeric are the valid characters.

Initially, I wrote the code as follows but it does not work for certain special characters such as ")", "(", "\" and "`" (there could be more that I may have missed). Basically, it complained that the script had syntax error.

case "$b" in
*@*) echo "Error: It has @";;
*~*) echo "Error: It has ~";;
*#*) echo "Error: It has #";;
*\**) echo "Error: It has *";;
*) echo "Directory is ok";;
esac

I believe there is a better way to code than listing everything in a case statement.

Hope someone can suggest a better solution. Thanks.

if you are checking for the path that exists

Code:

if [ -e $path ] ;then
 # Pass
else
 # Not valid path
fi

or

Code:

echo $path | awk '/[<>@*]/'

and check for status

No, I am not checking for valid path.

In my script, the user is required to key in a path. The path input by the user will be created.

My problem is in the validation of the path input by user.

Here's my more detailed script if it helps:

while :
do
echo "Please enter the directory: \c"
read b
if [ "$b" = "" ]; then
echo "ERROR: Directory should not be blank!"
else
# Validation: more condition is required. This is an area I need help
case "$b" in
*@*) echo "Error: It has @";;
*~*) echo "Error: It has ~";;
*#*) echo "Error: It has #";;
*\**) echo "Error: It has *";;
*) echo "Directory is ok"
break;;
esac
fi
done

Why dont you reverse your logic ? Look for the characters you need. Anything else will result in failure. You will have to enable the -noglob flag.

I have thought about it too but my skill in Bourne shell is limited and I could not figure out how I can do it. I have the following codes on my mind but I could not code something that is good enough to prevent the unwanted special characters from being entered by user:

# This will prevent user from entering /, _ & - which should be allowed
echo $b | grep "[^0-9]" > /dev/null 2>&1
if [ "$?" -eq "0" ]; then
echo "ERROR: Invalid Directory!"
fi

# This will prevent user from entering /, _ & - which should be allowed
echo $b | grep "[^a-z]" > /dev/null 2>&1
if [ "$?" -eq "0" ]; then
echo "ERROR: Invalid Directory!"
fi

# This will prevent user from entering /, _ & - which should be allowed
echo $b | grep "[^A-Z]" > /dev/null 2>&1
if [ "$?" -eq "0" ]; then
echo "ERROR: Invalid Directory!"
fi

How about just this sed statement.

Code:

sed -n -e "s+^[a-zA-Z0-9/_\-]*$+&+p"

Code:

[/tmp]$ echo 'ab!cada' | sed -n -e "s+^[a-zA-Z0-9/_\-]*$+&+p" 
[/tmp]$ echo 'ab21212cada' | sed -n -e "s+^[a-zA-Z0-9/_\-]*$+&+p"
ab21212cada
[/tmp]$ echo 'ab2121/2cada' | sed -n -e "s+^[a-zA-Z0-9/_\-]*$+&+p"
ab2121/2cada
[/tmp]$ echo 'ab2-_121/2cada' | sed -n -e "s+^[a-zA-Z0-9/_\-]*$+&+p"
ab2-_121/2cada

Not extensively tested.