Bash script backup program

Question

I've started bash scripting recently and currently I'm working on a program that simplifies backuping using rsync . I'd appreciate any feedback on what I've done wrong / what can be improved.

#!/bin/bash
# Copyright (C) 2020 ##########, e-mail: ##################
# saver comes with NO WARRANTY. This program is completely free and you can
# redistribute it under the GNU General Public License conditions.
# See https://www.gnu.org/licenses/gpl-3.0.txt for more information
# saver was made to simplify the process of backuping using rsync.
# version 2.2-1
if [[ ! $(id -u) == 0 ]]; then # making sure the progream is executed as root
 exec sudo 0ドル "$@"
fi
for ((i=1; i=i; i++)); do # here input variables of the script are read one by another using the for loop
 [[ -z ${!i} ]] && break
 case ${!i} in
 \-*) # this is where all the '-' options are
 case ${!i} in
 *s*) option=$option"sync" ;;& 
 *d*) rsyncoptions+=(-n) ;;& 
 *r*) rsyncoptions+=(--delete) ;;&
 *p*) rsyncoptions+=(--progress) ;;&
 *v*) rsyncoptions+=(-v) ;;&
 *h*) option=$option"help" ;;&
 *i*) option=$option"diskinfo" ;;
 esac
 ;;
 *) # here the paths and disks are set
 if [[ -b ${!i} ]]; then
 if [[ -z $sp ]]; then
 sdp="${!i}"
 else
 tdp="${!i}"
 fi
 else
 if [[ -b /dev/${!i} ]]; then
 if [[ -z $sp ]]; then
 sdp="/dev/${!i}" # sdp = sync disk path
 else
 tdp="/dev/${!i}" # tdp = target disk path
 fi
 else
 if [[ ${!i} == /* ]]; then 
 if [[ -z $sp ]]; then
 sp="${!i}" # sp = sync path
 else
 tp="${!i}" # tp = target path
 fi
 fi
 fi
 fi
 ;;
 esac
done
case $option in
 sync) # the -s option
 if [[ ! -e $sp ]]; then # checking if the path to sync from exists
 echo -e "The path to copy wasn't provided or doesn't exist\nType in 'saver -h' to see the list of commands"
 logger "saver: The path to copy wasn't provided or doesn't exist"
 exit
 fi
 if [[ -z $tp ]]; then # checking if the target path isn't empty
 echo -e "The target path wasn't provided\nType in 'saver -h' to see the list of commands"
 logger "saver: The target path wasn't provided"
 exit
 fi
 fsp=$sp # these stand for the final paths that will be put to the rsync command (final sync path / final target path)
 ftp=$tp
 if [[ $sdp ]]; then 
 echo "Unmounting the disk to copy"
 umount -q $sdp # mounting the sync external disk to a folder that's made
 
 echo "Creating /mnt/saverbd"
 mkdir /mnt/saverbd | grep -q a
 
 echo -e "Mounting the disk to copy to /mnt/saverbd\n"
 mount $sdp /mnt/saverbd 
 
 fsp=/mnt/saverbd${sp} # updates the final path if it's from an external disk
 fi
 if [[ $tdp ]]; then
 echo "Unmounting the target disk"
 umount -q $tdp # mounting the target external disk to a folder that's made
 echo "Creating /mnt/savertd"
 mkdir /mnt/savertd | grep -q a
 echo -e "Mounting the target disk to /mnt/savertd\n"
 mount $tdp /mnt/savertd
 ftp=/mnt/savertd${tp} # updates the final path if it's from an external disk
 fi
 if [[ ! -e $tp ]]; then
 echo "Creating ${ftp}"
 mkdir -p $ftp | grep -q a 
 fi
 echo
 rsync -aAX "${rsyncoptions[@]}" $fsp --exclude={"/dev/*","/proc/*","/sys/*","/tmp/*","/run/*","/mnt/*","/media/*","/lost+found"} $ftp
 if [[ $sdp ]]; then # unmounting the sync external disk and deleting the mount folder
 echo -e "\nUnmounting the copied disk"
 umount -q $sdp
 echo -e "Deleting /mnt/saverbd\n"
 rm -rf /mnt/saverbd
 fi
 if [[ $tdp ]]; then # unmounting the target external disk and deleting the mount folder
 echo -e "\nUnmounting the target disk"
 umount -q $tdp
 
 echo -e "Deleting /mnt/savertd\n"
 rm -rf /mnt/savertd 
 
 fi
 ;;
 diskinfo)
 lsblk -o NAME,SIZE,MOUNTPOINT,FSTYPE # shows the available disks and partitions
 ;;
 help) # the help page
 echo -e "\n Copyright (C) 2020 ###########, e-mail: ##################
 Version 2.2-1
\n saver comes with NO WARRANTY. This program is completely free and you\n can redistribute it under the GNU General Public License conditions.\n See https://www.gnu.org/licenses/gpl-3.0.txt for more information
\n saver was made to simplify the process of backuping using rsync.
\n This program will automaticly exclude these directories from syncing:\n /dev ; /proc ; /sys ; /tmp ; /run ; /mnt ; /media ; /lost+found.
 When typing in the disk name, you can use the full '/dev/(disk)' or just\n provide the name of the disk.
 Any disk you mention will be unmounted at the end of the program.
\n Usage:
\n -s [disk to copy (empty for current disk)] [copied path]\n [target disk (empty for current disk)] [target path]
\n Options:
\n -s Sync folders
 -r Delete any other files in the target folder
 -d Preform a 'dry run', no changes will be made
 -p Display progress for individual files (useful for large files)
 -v Display files that are being processed
 -i Show available disks/partitions
 -h Show this help\n"
 ;;
 *) # in case no valid option is provided
 echo -e "Invalid option provided\nType in 'saver -h' to see the list of commands"
 logger saver: "Invalid option provided" 
 ;;
esac

• Arthur: It does, what I mean by that is if the code I've written can be somehow optimized, if there can be any compatibility issues. I'm new to bash scripting so I tend to make mistakes.
• dariosicily: Welcome to Code Review. To increase the odds of receiving answers about your script, it could be better to modify the title of you post to include a brief description of the task implemented by the script.
• pacmaninbw: As @dariosicily indicated a better title might be bash backup script.
• Arthur: I changed the title, but "bash backup script" was taken.

Answer 1

loop

for ((i=1; i=i; i++)); do 
 [[ -z ${!i} ]] && break

you know that $# hold number of argument from command line ?

you can use

for ((i=1; i <= $# ; i++)) 

test

if [[ ! $(id -u) == 0 ]]

you know about != ? use

if [[ $(id -u) != 0 ]]

mkdir

what is the purpose of .. ?

mkdir /mnt/savertd | grep -q a

Do you want to get rid of "mkdir: cannot create directory ‘/mnt/savertd’: File exists" message ?

this won't work (message is printed on stderr, while | will collect stdout), use either

test -d /mnt/savertd || mkdir /mnt/savertd

or

mkdir -p /mnt/savertd

• second form is better, it will create all directory along the path, first one will fail if /mnt do not exists.
• mkdir -p will also not complain if directory exists.

echo -e

you have some

echo -e "Mounting the target disk to /mnt/savertd\n"

(削除) why use both -e (no new line) and a trailling \n (new line) ? (削除ここまで)

actually :

• -e enable interpretation of backslash escapes

long echo -e in help section can be replaced by a here documentation

cat <<EOF
 Copyright (C) 2020 ###########, e-mail: ##################
 Version 2.2-1
 saver comes with NO WARRANTY. This program is completely free and you
 can redistribute it under the GNU General Public License conditions.
 See https://www.gnu.org/licenses/gpl-3.0.txt for more information
 saver was made to simplify the process of backuping using rsync.
 This program will automaticly exclude these directories from syncing:
 /dev ; /proc ; /sys ; /tmp ; /run ; /mnt ; /media ; /lost+found.
 When typing in the disk name, you can use the full '/dev/(disk)' or just provide the name of the disk.
 Any disk you mention will be unmounted at the end of the program.
 Usage:
 -s [disk to copy (empty for current disk)] [copied path]
 [target disk (empty for current disk)] [target path]
 Options:
 -s Sync folders
 -r Delete any other files in the target folder
 -d Preform a 'dry run', no changes will be made
 -p Display progress for individual files (useful for large files)
 -v Display files that are being processed
 -i Show available disks/partitions
 -h Show this help
EOF

• Arthur: Thanks a lot I've heard about $#, but after I wrote that code so I haven't thought about that. All the other tips are really helpful too. I also wasn't sure how to use a here document, so I used a long echo, but this is much cleaner. Thanks again.
• Arthur: I'm not sure about what you said of echo -e with \n . echo -e doesn't block a new line. echo -n does that. I used 'echo -e' with '\n' to have two new lines.
• Archemar: yes my fault, -e enable interpretation of backslash escapes