I need SERIOUS noob help fixing this script (dont know anything about shell scripting)

riahc3 · 05-04-2019, 06:39 AM

Im trying to do a shell script with mostly three things in mind

1: Takes 3 parameters, first is a string and the second and third can be a int, float or string
2: I go thru functions and those functions should exit the shell script returning a exit code
3: The two "core" functions are always the same:

First a integer function: If it is less than, return 0, if it is greater than a but less than b, return 1, if it is greater than b return a 2

Then a string function. This is a two parter. If the function receives one parameter, if the parameter is equal to a value, return 0, if it isnt return 3. The second part would be if the function receives two parameters. If it is equal to the first parameter, return a 1, if it is equal to the second parameter, return a 2. Else, return 0.

So far, I have this shitty code:

https://codeshare.io/amvN6k

it doesnt work and I hope someone can lend a hand and fix it.

Thanks

BW-userx · 05-04-2019, 08:10 AM

returning in bash functions
https://www.linuxjournal.com/content...bash-functions

Comparison Operators
http://tldp.org/LDP/abs/html/comparison-ops.html

Conditionals
http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-6.html

BASH does not do floats (last time I checked)

I put my functions on top.

Code:

#!/bin/bash
OK=0
WARN=1
CRIT=2
UNKNOWN=3

#double brackets use them it is bash not sh

# Functions go below this line

check_load() #($2,$3)
{
	#poorly formed command for putting a value inside a variable
    #value=upsc cyberpower ups.load > /dev/stdout 2> /dev/null
    
    #Changed to
    value="$(upsc cyberpower ups.load)" # > /dev/stdout 2> /dev/null
    
    if [[ $value -lt $2 ]]
    then
        echo "OK. Load is $value"
       # return $OK
    #else if [ $value >= $2 && $value < $3 ]
   elif [[ $value -ge $2 && $value -lt $3 ]]
   then
            echo "WARNING. Load is $value"
            #return $WARN
    elif [[ $value -ge $3 ]]
    then
            echo "CRITICAL. Load is $value"
           # return $CRIT
    else
        echo "UNKNOWN. Load is $value"
       # return $UNKNOWN
    fi
}

check_model() #(2)
{
   #  value=upsc cyberpower ups.model > /dev/stdout 2> /dev/null
    
     value="$(upsc cyberpower ups.model)" # > /dev/stdout 2> /dev/null
     
    if [[ "$value" -eq "$2" ]]
    then
        echo "OK. Model is $value"
        #return $OK
    elif [["$value" -ne "$2"]]
    then
            echo "CRITICAL. Model is $value"
         #return $CRITICAL
    else
        echo "UNKNOWN. Model is $value"
        #return $UNKNOWN
    fi
}

#just another way to check for argc, amount of prams on cli

[[ $# -lt '3' ]] && { echo "enter 3 somethings" ; exit ; }

# ??? here you are checking for load and model, but asking for cli prams

case "$1" in
    load )
        check_load $2 $3 ;;
    model )
        check_model $2 ;;
		"" )
        echo -e "You need to supply a parameter." ;;
esac

not saying that is going to do what you want, but it is syntax-ually correct. Though you might want to slap some double quotes around all of your variables too. For that, if you do not know, quote me, safety net.

and that case statement is a little funny.

case statements

Code:

case EXPRESSION in

  PATTERN_1)
    STATEMENTS
    ;;

  PATTERN_2)
    STATEMENTS
    ;;

  PATTERN_N)
    STATEMENTS
    ;;

  *)
    STATEMENTS
    ;;
esac

so the cli should look something like this?

Code:

./script model 2 5

The growth of a BASH case statement incorporating multiple cli prams

https://www.linuxquestions.org/quest...ptions-557981/

also more error checking in your case statement too is advisable.

michaelk · 05-04-2019, 08:51 AM

Code:

check_model() #(2)
{
   #  value=upsc cyberpower ups.model > /dev/stdout 2> /dev/null
    
     value="$(upsc cyberpower ups.model)" # > /dev/stdout 2> /dev/null
     
    if [[ "$value" -eq "$2" ]]
    then
        echo "OK. Model is $value"
        #return $OK
    elif [["$value" -ne "$2"]]
    then
            echo "CRITICAL. Model is $value"
         #return $CRITICAL
    else
        echo "UNKNOWN. Model is $value"
        #return $UNKNOWN
    fi
}

Since you are passing one argument to the function it is $1 not $2...
OP, I don't understand purpose of the check_model function since the strings are either the same or not.

riahc3 · 05-05-2019, 05:57 AM

Quote:

Originally Posted by BW-userx

returning in bash functions
https://www.linuxjournal.com/content...bash-functions

Comparison Operators
http://tldp.org/LDP/abs/html/comparison-ops.html

Conditionals
http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-6.html

BASH does not do floats (last time I checked)

I put my functions on top.

Code:

#!/bin/bash
OK=0
WARN=1
CRIT=2
UNKNOWN=3

#double brackets use them it is bash not sh

# Functions go below this line

check_load() #($2,$3)
{
	#poorly formed command for putting a value inside a variable
    #value=upsc cyberpower ups.load > /dev/stdout 2> /dev/null
    
    #Changed to
    value="$(upsc cyberpower ups.load)" # > /dev/stdout 2> /dev/null
    
    if [[ $value -lt $2 ]]
    then
        echo "OK. Load is $value"
       # return $OK
    #else if [ $value >= $2 && $value < $3 ]
   elif [[ $value -ge $2 && $value -lt $3 ]]
   then
            echo "WARNING. Load is $value"
            #return $WARN
    elif [[ $value -ge $3 ]]
    then
            echo "CRITICAL. Load is $value"
           # return $CRIT
    else
        echo "UNKNOWN. Load is $value"
       # return $UNKNOWN
    fi
}

check_model() #(2)
{
   #  value=upsc cyberpower ups.model > /dev/stdout 2> /dev/null
    
     value="$(upsc cyberpower ups.model)" # > /dev/stdout 2> /dev/null
     
    if [[ "$value" -eq "$2" ]]
    then
        echo "OK. Model is $value"
        #return $OK
    elif [["$value" -ne "$2"]]
    then
            echo "CRITICAL. Model is $value"
         #return $CRITICAL
    else
        echo "UNKNOWN. Model is $value"
        #return $UNKNOWN
    fi
}

#just another way to check for argc, amount of prams on cli

[[ $# -lt '3' ]] && { echo "enter 3 somethings" ; exit ; }

# ??? here you are checking for load and model, but asking for cli prams

case "$1" in
    load )
        check_load $2 $3 ;;
    model )
        check_model $2 ;;
		"" )
        echo -e "You need to supply a parameter." ;;
esac

not saying that is going to do what you want, but it is syntax-ually correct. Though you might want to slap some double quotes around all of your variables too. For that, if you do not know, quote me, safety net.

and that case statement is a little funny.

case statements

Code:

case EXPRESSION in

  PATTERN_1)
    STATEMENTS
    ;;

  PATTERN_2)
    STATEMENTS
    ;;

  PATTERN_N)
    STATEMENTS
    ;;

  *)
    STATEMENTS
    ;;
esac

so the cli should look something like this?

Code:

./script model 2 5

The growth of a BASH case statement incorporating multiple cli prams

https://www.linuxquestions.org/quest...ptions-557981/

also more error checking in your case statement too is advisable.

Thanks a lot for the script. It looks really good and more or less what I need.....

While I build on it, question: You removed the return lines. How do I return 0, 1, 2, or 3 out of the script? Unless Ive missed something I dont see it.

riahc3 · 05-05-2019, 06:00 AM

Quote:

Originally Posted by michaelk

Code:

check_model() #(2)
{
   #  value=upsc cyberpower ups.model > /dev/stdout 2> /dev/null
    
     value="$(upsc cyberpower ups.model)" # > /dev/stdout 2> /dev/null
     
    if [[ "$value" -eq "$2" ]]
    then
        echo "OK. Model is $value"
        #return $OK
    elif [["$value" -ne "$2"]]
    then
            echo "CRITICAL. Model is $value"
         #return $CRITICAL
    else
        echo "UNKNOWN. Model is $value"
        #return $UNKNOWN
    fi
}

Since you are passing one argument to the function it is $1 not $2...
OP, I don't understand purpose of the check_model function since the strings are either the same or not.

check_model (or any other string based function, forget the name, its just a example) is a two parter than can be used in two ways

./check_model "hi" "bye" - If the value returned by check_model is "hi", it returns $WARNING. If the value returned by check_model is "bye", it returns $CRIT. Anything else other than those two, returns $OK

./check_model "hello" - If the value returned by check_model is "hello", it returns a $OK. Anything else, it returns a $CRIT.

This means that depending if check_model recieves two or three parameters, the logic is different.

michaelk · 05-05-2019, 07:56 AM

In your check_model function as stated is a string based function.

Code:

if [[ "$value" -eq "$2" ]]

The -eq is a binary operator and not used for strings. Use instead:

Code:

if [[ "$value" == "$2" ]]

Quote:

/check_model "hi" "bye" - If the value returned by check_model is "hi", it returns $WARNING. If the value returned by check_model is "bye", it returns $CRIT. Anything else other than those two, returns $OK

Code:

     value="$(upsc cyberpower ups.model)" 
     
    if [[ "$value" == "$1" ]]
    then
        echo "WARNING. Model is $value"
        return $WARNING
    elif [[ "$value" == "$2" ]]
    then
         echo "CRITICAL. Model is $value"
         return $CRITICAL
    else
        echo "OK. Model is $value"
        return $OK
    fi

You need to check the number of arguments since that determines how the function works.

BW-userx · 05-05-2019, 08:38 AM

Quote:

Originally Posted by riahc3

Thanks a lot for the script. It looks really good and more or less what I need.....

While I build on it, question: You removed the return lines. How do I return 0, 1, 2, or 3 out of the script? Unless Ive missed something I dont see it.

Ss you missed the link I gave you for function and return, it is the first link on top. I’m on my phone 📲 writing this so I’ll leave it as that.

riahc3 · 05-05-2019, 09:57 AM

Quote:

Originally Posted by michaelk

In your check_model function as stated is a string based function.

Code:

if [[ "$value" -eq "$2" ]]

The -eq is a binary operator and not used for strings. Use instead:

Code:

if [[ "$value" == "$2" ]]

Code:

     value="$(upsc cyberpower ups.model)" 
     
    if [[ "$value" == "$1" ]]
    then
        echo "WARNING. Model is $value"
        return $WARNING
    elif [[ "$value" == "$2" ]]
    then
         echo "CRITICAL. Model is $value"
         return $CRITICAL
    else
        echo "OK. Model is $value"
        return $OK
    fi

You need to check the number of arguments since that determines how the function works.

Thanks.

I updated my script again....I cant get the logic working on if the string function gets two or three parameters.

https://codeshare.io/amvN6k

This is what I have for now.

michaelk · 05-05-2019, 12:08 PM

For checking your syntax try www.shellcheck.net

riahc3 · 05-05-2019, 01:00 PM

I think I finally have it working

riahc3 · 05-05-2019, 06:32 PM

Working good except the string part....

I suspect that the string isnt clean; How do I remove all whitespaces from a variable and reassign it to the same variable? The string I am expecting will never have whitespaces, spaces, blanks, etc.

michaelk · 05-05-2019, 07:25 PM

There are several ways to debug your script and actually see what is happening. See the following link to see how to use the -x option.

http://tldp.org/LDP/Bash-Beginners-G...ect_02_03.html

BW-userx · 05-05-2019, 07:54 PM

Quote:

Originally Posted by riahc3

Working good except the string part....

I suspect that the string isnt clean; How do I remove all whitespaces from a variable and reassign it to the same variable? The string I am expecting will never have whitespaces, spaces, blanks, etc.

google 'how to remove blank spaces between strings sed linux'
echo your vars to the cli to see what it is looking at.
do something like this to see it all.

Code:

#!/bin/bash


echo "

[[ "$var1" == "$2" ]] && { echo " it is it is" ; } || { echo "it is not" ;}

"

echo the code itself. Or do what michaelk suggested.