Bash scripting: syntax error near unexpected token `done' - bash

Question

I am new to bash scripting and I have to create this script that takes 3 directories as arguments and copies in the third one all the files in the first one that are NOT in the second one.
I did it like this:
#!/bin/bash
if [ -d $1 && -d $2 && -d $3 ]; then
for FILE in [ ls $1 ]; do
if ! [ find $2 -name $FILE ]; then
cp $FILE $3
done
else echo "Error: one or more directories are not present"
fi
The error I get when I try to execute it is: "line 7: syntax error near unexpected token `done' "
I don't really know how to make it work!
Also even if I'm using #!/bin/bash I still have to explicitly call bash when trying to execute, otherwise it says that executing is not permitted, anybody knows why?
Thanks in advance :)

Answer 1

Couple of suggestions :
No harm double quoting variables
cp "$FILE" "$3" # prevents wordsplitting, helps you filenames with spaces
for statement fails for the fundamental reason -bad syntax- it should've been:
for FILE in ls "$1";
But then, never parse ls output. Check [ this ].
for FILE in ls "$1"; #drastic
Instead of the for-loop in step2 use a find-while-read combination:
find "$1" -type f -print0 | while read -rd'' filename #-type f for files
do
#something with $filename
done
Use lowercase variable names for your script as uppercase variables are reserved for the system. Check [this].
Use tools like [ shellcheck ] to improve script quality.
Edit
Since you have mentioned the input directories contain only files, my alternative approach would be
[[ -d "$1" && -d "$2" && -d "$3" ]] && for filename in "$1"/*
do
[ ! -e "$2/${filename##*/}" ] && cp "$filename" "$3"
done
If you are baffled by ${filename##*/} check [ shell parameter expansion ].
Sidenote: In linux, although discouraged it not uncommon to have non-standard filenames like file name.
Courtesy: #chepner & #mklement0 for their comments that greatly improved this answer :)

Answer 2

Your script:
if ...; then
for ...; do
if ...; then
...
done
else
...
fi
Fixed structure:
if ...; then
for ...; do
if ...; then
...
fi # <-- missing
done
else
...
fi
If you want the script executable, then make it so:
$ chmod +x script.sh
Notice that you also have other problems in you script. It is better written as
dir1="$1"
dir2="$2"
dir3="$3"
for f in "$dir1"/*; do
if [ ! -f "$dir2/$(basename "$f")" ]; then
cp "$f" "$dir3"
fi
done

Answer 3

this is not totally correct:
for FILE in $(ls $1); do
< whatever you do here >
done
There is a big problem with that loop if in that folder there is a filename like this: 'I am a filename with spaces.txt'.
Instead of that loop try this:
for FILE in "$1"/*; do
echo "$FILE"
done
Also you have to close every if statement with fi.
Another thing, if you are using BASH ( #!/usr/bin/env bash ), it is highly recommended to use double brackets in your test conditions:
if [[ test ]]; then
...
fi
For example:
$ a='foo bar'
$ if [[ $a == 'foo bar' ]]; then
> echo "it's ok"
> fi
it's ok
However, this:
$ if [ $a == 'foo bar' ]; then
> echo "it's ok";
> fi
bash: [: too many arguments

Answer 4

You've forgot fi after the innermost if.
Additionally, neither square brackets nor find do work this way. This one does what your script (as it is now) is intended to on my PC:
#!/bin/bash
if [[ -d "$1" && -d "$2" && -d "$3" ]] ; then
ls -1 "$1" | while read FILE ; do
ls "$2/$FILE" >/dev/null 2>&1 || cp "$1/$FILE" "$3"
done
else echo "Error: one or more directories are not present"
fi
Note that after a single run, when $2 and $3 refer to different directories, those files are still not present in $2, so next time you run the script they will be copied once more despite they already are present in $3.