How to handle space in filename in bash script?

Question

I want to automate rsyncing, and tried the following code:

TARGET="/media/USB\ DISK/Backup/"
rsync -av --delete ~/Data ${TARGET}

but the execution results in the following error:

rsync: link_stat "/media/USB\" failed: No such file or directory (2)
rsync: mkdir "/home/DISK/BACKUP" failed: No such file or directory (2)

because of the 'space' in the target filename. However, when I echo the command I can use that to run on the shell directly.

How to do it correctly (which brackets, with backslash or without?) and why?

Answer 1

There are two possibilities:

TARGET="/media/USB DISK/Backup/"
rsync -av --delete ~/Data "${TARGET}"

or

TARGET=/media/USB\ DISK/Backup/
rsync -av --delete ~/Data "${TARGET}"

The first one preserves the space by quoting the whole string. The second one preserves the space by escaping it with a backslash. Also, the argument to the rsync command needs to be quoted.

When the string is both double-quoted and the space is preceded by a backslash, as in TARGET="a\ b", the result is that TARGET contains a literal backslash which is probably not what you wanted. For more details, see the section entitled "Quoting" in man bash.