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Escape command parameters for re-use in Bash?

I want to save command parameters for re-use in a variable in Bash. The reason is they are very long and I use them multiple times.

SRC_FOLDER="src folder"
DST_FOLDER="dst folder"
PARAMS="--dry-run \"$SRC_FOLDER\" \"$DST_FOLDER\""
rsync $PARAMS

The problem is the space in the src and dst folder. Rsync thinks there are 4 folders instead of 2. I think I somehow have to escape the variables in line 3.

I cannot escape the folders in line 1 and 2 because they might have been passed to my bash script by parameter and I don't know the content.

Please also note that the src and dst folders may have other special signs like *, $, \, ", '.

Is this possible without using separate variables like this:

rsync $PARAMS "$SRC_FOLDER" "$DST_FOLDER"

Is there a solution?

Solution 
  • #!/bin/bash

rsync_args=(
    --dry-run
    "src folder"
    "dst folder"
)

rsync "${rsync_args[@]}"
    About the problem that I mentioned in my comment:

    The remote path in rsync commands is subject to word splitting.
    The following example is wrong:

    rsync -av ~/ user@server:'home backup 2021-12-04/'

    You have to write it like this:

    rsync -av ~/ user@server:'home\ backup\ 2021-12-04/'

    A way for fixing it automatically is:

    #!/bin/bash
remote_path='home backup 2021-12-04/'
qq="'\''"
rsync -av ~/ user@server:"'${remote_path//\'/$qq}'"