Assigning values to reference variables for a dynamic menu driven script.


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Top Forums Shell Programming and Scripting Assigning values to reference variables for a dynamic menu driven script.
# 1  
Question Assigning values to reference variables for a dynamic menu driven script.

How do I assign values to reference variables?

I am assigning a variable name to --> $user_var

Then I am trying to change its underlying variable value by
Code:
$((user_var))=$user_value

.. its failing,,

Please let me know if there is a way to do this dynamically..

FileA.props -->
Code:
myvar1=test1   #  Variable Names and values can be changed.
myvar2=test2
myvar3=test3
# EOF

testscript.sh -->
Code:
#!/usr/bin/ksh

# Helps to change values using this menu driven script
cvsprops=FileA.props  

# Executing include file, to simulate variable declaration.
# This is a must,, since its a parameter driven script.
. FileA.props

user_prompt='To Change Above Defaults Make A Selection:[n] '
PS3="${user_prompt}"

REDISPLAY=true  # Helps to exit from Menu.

while [ "$REDISPLAY" == "true" ]; do
select line in $(egrep -v "#" $cvsprops ) REVIEW DONE
do
        [ "$line" == "DONE" ] && REDISPLAY=false && break
        [ "$line" == "REVIEW" ] && break

        [ ! -n "$line" ] && echo " Invalid choice:[$REPLY]. Please make correct choice." && continue

        user_var="$(echo $line | cut -d= -f1)"
        user_value="$(echo $line | cut -d= -f2)"

        #echo "Length of $user_value --> ${#user_value}"

        # if required variable is not set. Prompt user to set it.
        if [ ! -n "$user_value" ]; then
                echo "Set --> ${user_var} ?: \c"
        else
                echo "Change --> ${user_var}:[${user_value}] ?: \c"
        fi
        read user_value
        if [ -n $user_value ]; then
            echo "new value for ${user_var} --> $user_value" 
           
            # *** This is failing.. How can I change say 
            # myvar1 value to 'mytest4' !!?
            $((user_var))=$user_value
        fi

done # End of - select

done # End of while
# EOF

Code:
$>testscript.sh
......< Menu > .........
To Change Above Defaults Make A Selection:[n] 4
Set --> cvsRepositoryUserID ?: n
new value for myvar1 --> n
testscript.sh[]: myvar1: bad number


Last edited by Franklin52; 04-29-2010 at 06:36 PM.. Reason: Please use code tags!
# 2  
Code:
$((user_var))=$user_value

That is arithmetic
try:
Code:
eval "$user_var=$user_value"

# 3  
Thanks for the response.
While your suggested code is not failing,,its not solving the problem either.
Code:
        read user_value
        if [ -n $user_value ]; then
                echo "new value for ${user_var} --> $user_value"

                # *** This is failing.. How can I change say
                # myvar1 value to 'mytest4' !!?
                eval "$user_var=$user_value"
        fi

When I display variable values,, they are still pointing to old values.

Output --->
Code:
icoe12:/export/apps/rh50ip2/Scripts/opsUtils/cvstools/junk/test> testscript.sh
1) myvar1=test1
2) myvar2=test2
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 2
Change --> myvar2:[test2] ?: test4
new value for myvar2 --> test4
To Change Above Defaults Make A Selection:[n] 4
1) myvar1=test1
2) myvar2=test2
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n]

I would appreciate if someone tries my code on their system and get it working..
FileA.props -->

Code:
#  Variable Names and values can be changed.
myvar1=test1   
myvar2=test2
myvar3=test3
# EOF

# 4  
I tested your script and it works fine.
The thing is that you display the content of the file (by selecting REVIEW), not the values of variables.
Do you want the script to modify the values in FileA.props?
else, you'll have to modify the select statement.

The REDISPLAY variable seems useless.
# 5  
A possible solution...
Try and adapt :
Code:
#!/usr/bin/ksh

#==============================================================================
# F U N C T I O N S . . .
#==============================================================================

ReadProps () {
  local list
  list=$(sed 's/#.*//' ${cvsprops} | \
         awk -F= '
            NF { count++;
                 printf "Uvar[%d]=%s; Uval[%d]=%s;", count, $1, count, $2;
                 printf "Uchoice[%d]=%s;", count, $0;
               }
            END { printf "Ucount=%d", count }'
        )
   eval ${list}
}

WriteProps () {
   local i var val
   i=1
   while (( i <= Ucount ))
   do
      var=${Uvar[$i]}
      val=${Uval[$i]}
      echo "${var}='${val}'"
      (( i+=1 ))
   done > ${cvsprops}
}

#==============================================================================
# M A I N . . . 
#==============================================================================

# Helps to change values using this menu driven script
cvsprops=FileA.props  


user_prompt='To Change Above Defaults Make A Selection:[n] '
PS3="${user_prompt}"

REDISPLAY=true  # Helps to exit from Menu.


while [ "$REDISPLAY" = "true" ]
do    
   ReadProps

   select line in "${Uchoice[@]}" REVIEW DONE
   do
        [ "$line" = "DONE" ] && REDISPLAY=false && break
        [ "$line" = "REVIEW" ] && break

        [ -z "$line" ] && echo " Invalid choice:[$REPLY]. Please make correct choice." && continue

        user_var=${Uvar[$REPLY]}
        user_value="${Uval[$REPLY]}"

        # if required variable is not set. Prompt user to set it.
        if [ -z "$user_value" ]; then
                echo "Set --> ${user_var} ?: \c"
        else
                echo "Change --> ${user_var}:[${user_value}] ?: \c"
        fi
        read user_value
        if [ -n "$user_value" ]; then
            Uval[$REPLY]="${user_value}"
            eval ${user_var}='${user_value}'
            WriteProps
            eval user_value=\$${user_var}
            echo "new value for ${user_var} --> $user_value" 
            break
        fi

   done # End of - select

done # End of while
# EOF

Input file FileA.props :
Code:
#  Variable Names and values can be changed.
myvar1=test1   
myvar2=test2
myvar3=test3
# EOF

Sample execution :
Code:
$ kc.sh
1) myvar1=test1
2) myvar2=test2
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 1
Change --> myvar1:[test1] ?: First test
new value for myvar1 --> First test
1) myvar1=First test
2) myvar2=test2
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 1
Change --> myvar1:[First test] ?: 
To Change Above Defaults Make A Selection:[n] 2
Change --> myvar2:[test2] ?: 2222
new value for myvar2 --> 2222
1) myvar1=First test
2) myvar2=2222
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 1
Change --> myvar1:[First test] ?: 1111
new value for myvar1 --> 1111
1) myvar1=1111
2) myvar2=2222
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 5
$ sh kc.sh
1) myvar1=1111
2) myvar2=2222
3) myvar3=test3
4) REVIEW
5) DONE
To Change Above Defaults Make A Selection:[n] 5
$

Jean-Pierre.
# 6  
Smilie Jean-Pierre, Thanks a lot for taking time to solve it.. It works great..
SmilieSmilie SmilieSmilie
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