Bash shell scripting rsync with variables [duplicate] - bash

Question

This question already has answers here:
Bash: need help passing a a variable to rsync
(3 answers)
Closed 4 years ago.
I have the following for-loop which loops through all the given sources that need to be copied.
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az $exclude $i $destination
done
However, the exclude option is not working.
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az "$exclude" "$i" "$destination"
done
If I use the code above, rsync will exit and give an error that it is an unknown option.
If I simply use the following code, it works, but I want to use a variable for the exclude option.
for i in "${sources[#]}"; do
rsync -az --exclude 'exclude_folder/exclude_file' $i $destination
done

Answer 1

I would use eval.
Your code:
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync -az "$exclude" "$i" "$destination"
done
would be then (I'm trying to be as close to your logic as possible):
for i in "${sources[#]}"; do
exclude="--exclude 'exclude_folder/exclude_file'"
rsync_command="rsync -az $exclude $i $destination"
eval rsync_command
done
From the eval man pages:
eval
Evaluate several commands/arguments
Syntax
eval [arguments]
The arguments are concatenated together into a single command, which
is then read and executed, and its exit status returned as the exit
status of eval. If there are no arguments or only empty arguments, the
return status is zero.
eval is a POSIX `special' builtin
EDIT
Gordon Davisson is right about the bugs/insecurities in eval. If any other solution is available then it is better to use it. Here the bash arrays are better. The array answer is superior answer.
Please see the answer at Bash: need help passing a a variable to rsync

Answer 2

Example list directories to exclude (also wildcharts) :
#!/bin/sh
export PATH=/usr/local/bin:/usr/bin:/bin
LIST="rootfs usr data data2"
for d in $LIST; do
rsync -az --exclude /$d/ .....
done