题目
Write a script called homebackup that automates tar so the person executing the script always uses the desired options (cvp) and backup destination directory (/var/backups) to make a backup of his or her home directory. Implement the following features:
-
Test for the number of arguments. The script should run without arguments. If any arguments are present, exit after printing a usage message.
-
Determine whether the backups directory has enough free space to hold the backup.
-
Ask the user whether a full or an incremental backup is wanted. If the user does not have a full backup file yet, print a message that a full backup will be taken. In case of an incremental backup, only do this if the full backup is not older than a week.
-
Compress the backup using any compression tool. Inform the user that the script is doing this, because it might take some time, during which the user might start worrying if no output appears on the screen.
-
Print a message informing the user about the size of the compressed backup.
参考实现
#!/bin/bash
ARG_NUM=$#
if [ $ARG_NUM -gt 0 ]
then
echo "Usage: ./homebackup.sh "
exit
fi
FREE_SPACE=`df /home/backup | tail -1|awk ‘{print $4}‘`
USER_CHOICE=0
echo "Please input your choice:"
echo "0,full backup"
echo "1,incremental backup"
BACKUP_FILE_NAME="backup"$(date +%Y-%m-%d)".tar.gz"
read USER_CHOICE
case $USER_CHOICE in
0)
echo "start to backup in full mode"
;;
1)
echo "start to backup in incremental mode"
if [ -f "/home/backup/backup.tar.gz" ]
then
LAST_BACK_TIME=`stat /home/backup/backup.tar.gz |grep Modify|awk -F. ‘{print $1}‘ |awk ‘{print $2" "$3}‘`
LAST_BACK_TIME=`date -d "$LAST_BACK_TIME" +%s`
NOW=`date -d "-7 day" +%s`
if [ $LAST_BACK_TIME -gt $NOW ]
then
echo "You cannot do backup operation"
echo "The last backup is on " `date -d @"$LAST_BACK_TIME" +%Y-%m-%d`
exit
fi
fi
;;
*)
echo "wrong operation"
exit
;;
esac
tar -cvf $BACKUP_FILE_NAME *.sh
BACK_UP_SIZE=`ls -la $BACKUP_FILE_NAME|awk ‘{print $5}‘ `
if [ $BACK_UP_SIZE -gt $FREE_SPACE ]
then
echo "Insufficient space in /home/backup, it need $BACK_UP_SIZE bytes"
exit
fi
mv $BACKUP_FILE_NAME /home/backup/backup.tar.gz