Menu based selection in Shell scripting

Question

I have a Shell Script to do 4 tasks within a menu. The code I have so far is (basic one i guess) without a menu. I wanted it to add the menu at the start and i have tried many ways (using case statement, if else and while loop). Nothing has been worked out.

#!/bin/bash

cd /

echo "1. Basic Details"
echo "2. CPU Information"
echo "3. Network information"
echo "4. All"
echo "5. Cancel"
read option 



if [ $option -eq 1 ];then


    echo ">>>>> Server Name, Date, UPtime <<<<<"
    echo "====================================="
    echo "Date :- `date`"
    echo " "
    echo "Host Name :- `hostname`"
    echo " "
    echo " OS Version"
    oslevel -g
    echo " "
    echo " UPTIME :- "
    uptime
    echo " "
    echo " "

elif [ $option -eq 2 ];then


    echo ">>>>>    CPU and Memory Info.   <<<<<"
    echo "====================================="
    echo " "
    echo 
    echo "          CPU :- `lsdev | grep Processor | wc -l`"
    echo " "
    echo "       Memory :- `lsattr -El mem0 | tail -1`"

    echo " "
    echo " "
    echo "====================================="
    echo ">>>>> Important Kernel Params.  <<<<<"
    echo "====================================="
    echo " "
    echo "****************************************"
    echo " "
    lsattr -El aio0


elif [ $option -eq 3 ];then

    echo ">>>>> Memory Usage Information  <<<<<"

    um=`svmon -G | head -2|tail -1| awk {'print $3'}`
    um=`expr $um / 256`
    tm=`lsattr -El sys0 -a realmem | awk {'print $2'}`
    tm=`expr $tm / 1024`
    fm=`expr $tm - $um`
    ump=`expr $um \* 100`
    ump=`expr $ump / $tm`
    echo " "
    echo "Memory Used :- "$ump"%"
    echo " "
    echo "----------------------";
    echo "Memory Information\n";
    echo "total memory = $tm MB"
    echo "free memory = $fm MB"
    echo "used memory = $um MB"
    echo "-----------------------\n";
    echo " "
    echo " "

else
 echo "Enter correct option"
fi  

Please suggest with corrections. Not added the option 4 in script( i need it to display all the information)

Answer 1

bash has the select builtin:

select val in cherry banana apple ;  do
    echo "$val"
    # do other things with $val
    # ...
    break # Leave this out if you want to run
          # the menu forever in an endless loop
done 

Answer 2

I quite don't understand "add the menu at start", In you script itself menu is the first printed statements. Here is the example of repeated menu where exiting the program is depends on user input

#!/bin/sh
#method to just print your menu
printmenu() {
   echo "1. Operation 1"
   echo "2. Operation 2"
   echo "3. Exit"
}

operation1() {
   echo "Operation 1 is performed..!"
}

operation2() {
   echo "Operation 2 is performed..!"
}

while [ 1 ]
do
   printmenu # printing menu
   read u_option

  #case handling the user inputs
  case $u_option in
     1) operation1;; # calling function for operation1
     2) operation2;; # calling function for operation2
     3) echo "Terminating the program as per your request"
        exit;;
     *) echo "Invalid option, provide only valid integers"
   esac
done

Answer 3

This is more of a code review.

• for menus, use select
• use functions to encapsulate functionality
• paste your code into http://www.shellcheck.net

#!/bin/bash

main() {
    cd /

    PS3="Enter a choice: "
    select ch in "Basic Details" "CPU Information" "Network Information" All Cancel
    do
        case $ch in 
            "Basic Details")
                basicDetails
                ;;
            "CPU Information")
                cpuInfo
                ;;
            "Network Information")
                memUsage            # you need to fix the menu text
                ;;
            All)
                basicDetails
                cpuInfo
                memUsage
                ;;
            Cancel)
                break
                ;;
        esac
    done
}

basicDetails() {
    echo ">>>>> Server Name, Date, UPtime <<<<<"
    echo "====================================="
    echo "Date :- $(date)"
    echo " "
    echo "Host Name :- $(hostname)"
    echo " "
    echo " OS Version"
    oslevel -g
    echo " "
    echo " UPTIME :- "
    uptime
    echo " "
    echo " "
}

cpuInfo() {
    echo ">>>>>    CPU and Memory Info.   <<<<<"
    echo "====================================="
    echo " "
    echo 
    echo "          CPU :- $(lsdev | grep -c Processor)"
    echo " "
    echo "       Memory :- $(lsattr -El mem0 | tail -1)"

    echo " "
    echo " "
    echo "====================================="
    echo ">>>>> Important Kernel Params.  <<<<<"
    echo "====================================="
    echo " "
    echo "****************************************"
    echo " "
    lsattr -El aio0
}

memUsage() {
    echo ">>>>> Memory Usage Information  <<<<<"

    um=$(svmon -G | head -2|tail -1| awk '{print $3}')
    um=$(( um / 256 ))
    tm=$(lsattr -El sys0 -a realmem | awk '{print $2}')
    tm=$(( tm / 1024 ))
    fm=$(( tm - um ))
    ump=$(( um * 100 / tm ))
    echo " "
    echo "Memory Used :- $ump%"
    echo " "
    echo "----------------------"
    echo "Memory Information"
    echo
    echo "total memory = $tm MB"
    echo "free memory = $fm MB"
    echo "used memory = $um MB"
    echo "-----------------------"
    echo
    echo " "
    echo " "
}

main "$@"