Linux/sh: How to listing only files in folder (with witespace) and save into a variable in one line - shell

Question

I try to get the lists of files in that format (with witespaces):
"file1.html" "file 2.php" "file_3.php"
#!/bin/sh
WEB_DIR="/volume1/web"
IFS=$'\n'
for file in $(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f) ; do
printf "\"$file\" "
done
output:
"/volume1/web/.htaccess" "/volume1/web/file.html" "/volume1/web/a b.php"
and the output is perfect but... how to put this output to the variable?
I do this...
IFS=$'\n'
for file in $(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f) ; do
mystring+=$(printf "\"$file\" ")
done
echo ${mystring}
In output I have this:
tmp.sh: line 48: mystring+="/volume1/web/.htaccess" : not found

Answer 1

Note:
The answer below accepts the premise of the question: to build a single string value with a list of double-quoted file paths, such as the one shown in the question (
"/volume1/web/.htaccess" "/volume1/web/file.html" "/volume1/web/a b.php")
However, the OP ultimately wanted to use that string as part of another command, which does not work, because the embedded double quotes are no longer recognized as string delimiters that identify separate arguments when you reference the string variable.
The correct solution is to use find ... -exec ...+ (in this case) or, generally, xargs to pass a list of filenames as operands (arguments) to another command; e.g., to pass the filenames to command foo ({} robustly passes all file paths, whether they contain spaces or not):
find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -exec foo -bar {} +
If the list of filenames doesn't go at the end of the target command line, an intermediate sh -c command is necessary:
find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -exec sh -c 'foo -bar "$#" -baz' - {} +
You've tagged your question bash, but your shebang line targets sh, where Bash extensions to the POSIX shell specification aren't guaranteed to be available.
In your case (it sounds like you're using dash, which act as /bin/sh on Ubuntu):
ANSI C-quoted strings such as $'\n' aren't available - $'\n' expands to literal $\n.
This means that any of these 3 literal chars. - $, \ or n serve as the field separator - in your case that just happened to work, because the file paths happened not to contain these characters.
Operator += isn't recognized - the whole token mystring+="/volume1/web/.htaccess" is treated as a command name, which causes the error you're seeing.
Possible solutions:
If you do want to target Bash, replace #!/bin/sh with #!/bin/bash.
Note that for your bash code to be fully robust, you should turn off globbing (set +f) in addition to setting $IFS.
Your code can be streamlined - see below.
If not (if your code must be portable), you must find POSIX-compliant alternatives - see below.
Here's a portable solution (works with any POSIX-compliant sh):
while IFS= read -r file; do
mystring="$mystring$(printf "\"$file\" ")"
done <<EOF
$(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f)
EOF
echo "$mystring"
A much more efficient variant that uses find ... -exec ... + to produce the output with (typically) a single printf call:
IFS= read -r mystring <<EOF
$(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -exec printf '"%s" ' {} +)
EOF
echo "$mystring"
The bash equivalent, using a process substitution (<(...)):
IFS= read -r mystring < \
<(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -exec printf '"%s" ' {} +)
echo "$mystring"
Also note that GNU find has a built-in -printf action that supports a variety of format strings, which makes calling the external printf utility unnecessary:
IFS= read -r mystring < <(find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -printf '"%p" ')
echo "$mystring"

Answer 2

I am not really sure why we are bothering with the intermediate step of using a variable:
find "${WEB_DIR}" -mindepth 1 -maxdepth 1 -type f -print0 | xargs -0 /usr/syno/bin/7z \
a "${BACKUP_DIR}/backup_webfiles_${TIMESTAMP}.7z" -xr!thumbs.db -xr!#eaDir -xr!#tmp \
-xr!#recycle -xr!lost+found -xr!.DS_Store -t7z -m0=lzma2 -ms=off -mhe -mmt -mx9 \
-v${SPLIT_VOLUME} -p"${PASSWORD}"
I am not sure if you have to tell 7z that the files are coming from stdin, so you might have to add a hyphen (-) where "${only_files}" used to be??