bash shell:意外标记‘`else’附近的语法错误

Question

我正在遵循实现脚本的说明，这对我来说似乎很清楚，在运行它时，我被告知第36行有一个错误。似乎不能理解这个问题。

line 36: syntax error near unexpected token `else'
line 36: `  else'

代码：

   if [ "$answer" = "y" ] #Backup all VMs if answer is yes
  then
          for num in 1 2 3 #Determiant loop for 3 arguments: 1, 2, and 3
  do
          echo "Backing up VM #$num"
          gzip < /var/lib/libvirt/images/centos$num.qcow2 > /root/centos$num.qcow2.backup.gz
          echo "VM #$num BACKUP DONE"
  done

  elif [ "$answer = "n" ]
  then
          read -p "Which VM should be backed up? '(1/2/3)': " numanswer
   until echo "$numanswer" | grep "^[123]$" >> /dev/null # Look for match of single digit: 1, 2, or 3
  do
           read -p "Invalid Selection. Select 1,2, or 3: " numanswer
          echo "Backing up VM #$numanswer"
  gzip < /var/lib/libvirt/images/centos$numanswer.qcow2 > /root/centos$numanswer.qcow2.backup.gz
          echo "VM #$numanswer BACKUP DONE":
          else ### line 36 
          echo "Invalid Selection... Aborting program"

  exit2
  fi

Answer 1

该脚本应为：

 27 elif [ "$answer = "n" ]
 28 then
 29     read -p "Which VM should be backed up? '(1/2/3)': " numanswer
 30     until echo "$numanswer" | grep "^[123]$" >> /dev/null # Look for match of single digit: 1, 2, or 3
 31     do
 32         read -p "Invalid Selection. Select 1,2, or 3: " numanswer
 33     done
 34     echo "Backing up VM #$numanswer"
 35     gzip < /var/lib/libvirt/images/centos$numanswer.qcow2 > /root/centos$numanswer.qcow2.backup.gz
 36     echo "VM #$numanswer BACKUP DONE":
 37 else
 38     echo "Invalid Selection... Aborting program"
 39     exit2
 40 fi

注意33中的done，这是必需的。

Answer 2

这似乎工作得很好：

#!/bin/bash
while true
    do
        read -r -p $'Which VM should be backed up? [1, 2, 3, or All]\n\n\tPlease enter your selection: ' numanswer
        case "$numanswer" in
            1)
                echo "Backing up VM #1"
                gzip < /var/lib/libvirt/images/centos1.qcow2 > /root/centos1.qcow2.backup.gz
                echo "VM #1 BACKUP DONE"
                break
                ;;
            2)
                echo "Backing up VM #2"
                gzip < /var/lib/libvirt/images/centos2.qcow2 > /root/centos2.qcow2.backup.gz
                echo "VM #2 BACKUP DONE"
                break
                ;;
            3)
                echo "Backing up VM #3"
                gzip < /var/lib/libvirt/images/centos3.qcow2 > /root/centos3.qcow2.backup.gz
                echo "VM #3 BACKUP DONE"
                break
                ;;
            All)
                for num in 1 2 3
                    do
                        echo "Backing up VM #$num"
                        gzip < /var/lib/libvirt/images/centos$num.qcow2 > /root/centos$num.qcow2.backup.gz
                        echo "VM #$num BACKUP DONE"
                    done
                break
                ;;
            *)
                echo "Invalid input"
                continue
                ;;
        esac
    done

Answer 3

您有一条until语句，但没有用于关闭循环的done。所以else迷失在他们的。