I have a simple bash script which copies files using rsync:

#! /bin/bash

read -p "enter source: " sdir
read -p "enter target: " tdir
read -p "enter name of log file: " lfile

current_date=$(date +%Y-%m-%d)

rsync_options="-avb --exclude Documents --exclude Desktop --exclude Music --exclude Downloads --exclude Videos --exclude Backgrounds --exclude Pictures --exclude .cache --exclude .cabal --backup-dir $target/current_date --delete"

$(which rsync) $rsync_options $sdir $tdir/$current_date.$lfile >> /home/paul/Documents/logs/backup_$current_date.$lfile

When I run this, I get

paul on arch ~ took 8s
10:07 ❯ backup1.sh
enter source: ~/
enter target: /run/media/paul/7b266343-ee12-4e6b-bff5-77307f299ba0/Vostro/
enter name of log file: home
rsync: [sender] change_dir "/home/paul/~" failed: No such file or directory (2)
rsync error: some files/attrs were not transferred (see previous errors) (code 23) at main.c(1338) [sender=3.3.0]

However, when I delete $sdir and write in the actual directory ~/, the script runs as expected. Why is the variable $sdir not passed, but the others are?

I tried running the script from several directories, although I do not see that this would make a difference. I rewrote this script with the read bit:

#! /bin/bash

if [ $# -ne 3 ]
then 
    echo "Usage: backup.sh <source_directory> >target_directory>"
    echo "Please try again."
    exit 1
fi   

if ! command -v rsync > /dev/null 2>&1
then echo "This script requires rsync"
    exit 2
fi

current_date=$(date +%Y-%m-%d)

rsync_options="-avb --exclude Documents --exclude Desktop --exclude Music --exclude Downloads --exclude Videos --exclude Backgrounds --exclude Pictures --exclude .cache --exclude .cabal --backup-dir $2/current_date --delete"

$(which rsync) $rsync_options $1 $2/$current_date.$3 >> /home/paul/Documents/logs/backup_$current_date.$3.log

# run this script doing something like: backup.sh /home/paul /run/media/paul/7b266343-ee12-4e6b-bff5-77307f299ba0 paul

and this worked as expected