How to fix '[: too many arguments' for jpg files [duplicate] - linux

Question

This question already has answers here:
Meaning of "[: too many arguments" error from if [] (square brackets)
(6 answers)
Closed 3 years ago.
I am making a script that should play any media files in the downloads folder and shred it if I do not want to keep them. It works on the file types .swf, .webm, .gif, .png but not .jpg. For jpg I get this error
'[: too many arguments'
If I change it to .png without changing anything else then it works.
I have tried to change it from *jpg to *png, and that works. Changing it back to *jpg, gods forbid that. I can't find anything on google that can help me with this.
#!/bin/bash
cd Downloads
get_files () {
for i in *.*; do
[ -f "$i" ] || break
echo "Playing '$i'"
if [ "$i" == *swf ]; then
./flashplayer $i
shred_file $i
elif [ "$i" == *webm ]; then
vlc $i
shred_file $i
elif [ "$i" == *gif ]; then
xdg-open $i
shred_file $i
elif [ "$i" == *jpg ]; then
xdg-open $i
shred_file $i
elif [ "$i" == *png ]; then
xdg-open $i
shred_file $i
fi
done
}
shred_file () {
echo ""
echo "Do you want to shred the file?"
read r
if [ "$r" == "y" ]; then
shred -uvz $1
else
echo keep
fi
}
get_files
I expect this script to be able to open .jpg files and any other file types defined in this script. I do not expect this error to occur at all

Answer 1

In Bash (and other POSIX shells), [ ... ] is not particularly magical; in fact, it can be implemented as a completely separate program, though in practice most shells do provide it as a builtin. (If you run type -a [, you'll most likely see that your system has both a builtin and a separate program.)
So the problem is that if your current directory contains files whose names end with jpg, such as foojpg and barjpg, then this command:
[ "$i" == *jpg ]
expands to something like this:
[ my.file == foojpg barjpg ]
which is obviously not what you want.
And even if you escaped the * to prevent the filename-expansion ([ "$i" == \*jpg ] or [ "$i" == '*jpg' ]), it still wouldn't do what you want, because [ ... ] doesn't support this sort of glob comparison.
Since you're specifically using Bash, your best bet is to use its special [[ ... ]] syntax, which is magical, and has special support for globs:
[[ "$i" == *jpg ]]
(And likewise for all of your other tests.)

Answer 2

bash will expand *jpg to all the file names which end 'jpg'. And so on for all the file suffixes. The '.jpg' test causes an error probably because there are a number of files that match *.jpg.
Better to test the suffix itself:
suffix=${i#*.} # if $i is file.jpg yields 'jpg'
And then do tests for the suffix value:
if [ "$suffix" == "swf" ]; then
./flashplayer $i
shred_file $i
elif [ "$suffix" == "webm" ]; then
vlc $i
shred_file $i
...
...
Incidentally, for the for loop, you could (if appropriate) specify the file types the loop should process:
shopt -s nullglob
for i in *.{swf,gif,png,jpg,jpeg}; do