How to write bash script while using command as condition in if statement?

Question

I am writing a bash script to process input from html form.

First problem is that I can't get my if statement to work while using command as condition. I am trying to check user input of middle initial and adjust it to make sure it can be combined into $answer.

Here is example of how it is suppose to process.

User inputs three different fields from html form; first name, middle initial, last name.

First name : George
Middle Initial : W.
Last name : Bush

Shell script will process and compare user input and actual answer. Actual answer is "George W. Bush"

User input:
George W. Bush = correct echo "You are correct!"
George W Bush = correct by automatically placing period after "W"
George Bush != wrong and echo "No middle initial!"
Geor W. Bus != wrong and echo "First name and last name are wrong!"

#! /bin/bash
echo Content-type: "text/html"
echo ""
read input #name variable $first, $middle, $last name
first=`user input`
middle=`user input`
last=`user input`
president=`actual answer, full name of president`
answer=`user answer, combination of $first, $middle, $last`
correctF=`actual first name from $president`
correctM=`actual middle initial from $president`
correctL=`actual last name from $president`
#cut by column from $president

First problem starts here.

if [[ $(echo $middle | wc -l) = 1 ]] ; then
 middle=`echo "$middle""."` 
 #check if middle initial variable was entered with just the letter and place a period after
elif [[ $(echo $middle | grep '.') = 'true' ]] ; then
 middle=`echo "$middle"`
 #check if middle initial variable was entered with the period and leave it as is
else
 middle=`'false'`
 #no middle initial variable was entered and is null
fi

Second problem in while loop with if statement.

I am trying to compare the user input $answer to actual answer $president and echo what is wrong with $answer. Nothing is echoed for this section.

while [ "$president" -ne "$answer" ] #not working
 do
 if [ "$first" -ne "$correctF" ]
 then
 echo "Wrong first name!"
 elif [ "$middle" -ne "$correctM" ]
 then
 echo "Wrong middle initial!"
 elif [ "$last" -ne "$correctL" ]
 then
 echo "Wrong last name!"
 elif [ -z "$middle" -ne "$correctM" ]
 then
 echo "No middle initial!"
 elif [ "$first" -ne "$correctF" ] && [ "$last" -ne "$correctL" ]
 then
 echo "Wrong first and last name!"
 elif [ "$first" -ne "$correctF" ] && [ "$middle" -ne "$correctM" ]
 then
 echo "Wrong first name and middle initial!"
 elif [ "$middle" -ne "$correctM" ] && [ "$last" -ne "$correctL" ]
 then
 echo "Wrong middle initial and last name!"
 elif [ "$first" -ne "$correctF" ] && [ "$middle" -ne "$correctM"] && [ "$last" -ne "$correctL" ]
 then
 echo "You got it all wrong!"
 else
 echo "You are correct!"
 fi

I need to properly implement a command into if statement condition and write a if statement with multiple conditions.

• Michael Vehrs: Please add the input you get and the result you expect.
• cas: This script has so much wrong with it that I don't even know where to begin....except maybe with: if this script is meant to process input from a HTML form, then do some basic research on writing CGI scripts before you write any code
• James: I've included examples of how it is suppose to process and show result. It is suppose to process input from a HTML form. Sorry for the confusion.
• Henrik supports the community: So what happens if I enter "You suck; rm -fr /" as first name?
• Wildcard: Agree with @cas. James, if you are processing input from an HTML form using this script, you are right now laying your server wide open to total destruction.

Answer 1

cas says, "This script has so much wrong with it that I don't even know where to begin...". Well, I have some ideas on where to begin:

• Please don’t ask us to debug your script and then post pseudo-code. Your first code block contains backticks (`) in places where they will not work.
• Please be more explicit. "I can’t get my if statement to work" isn’t very helpful to us. What happens?
• You should always quote your shell variable references (e.g., "$middle") unless you have a good reason not to, and you’re sure you know what you’re doing.
• $(echo "$middle" | grep '.') will equal 'true' only if "$middle" equals true. The output of grep is the content of the line(s) from the input that match the pattern given as a parameter.
• . is a pattern that means "any character", so grep '.' will match any non-blank input line. To check for an actual period (.), use grep '\.'. Note that this will match W. but also .W, ..., 3.14159, etc.
• Why are you doing a while? Do you expect that code to execute more than once? Do you expect it to get different results when executed repeatedly on the same data? Where’s the end of the loop?
• -eq and -ne should be used only when comparing integers; use = and != for strings.
• What do you mean by -z STRING1 -ne STRING2?

There may be other problems, but my eyes hurt too much to look at this any longer.