[hackers] [farbfeld] Shellcheck 2ff fixes || FRIGN

[git]

commit 1f8903d1689e5f796fbe227587081d28f864cb07
Author:     FRIGN <d...@frign.de>
AuthorDate: Wed Sep 7 23:10:05 2016 +0200
Commit:     FRIGN <d...@frign.de>
CommitDate: Wed Sep 7 23:10:05 2016 +0200

    Shellcheck 2ff fixes
    
    I was inspired by the current discussion on dev@ to use shellcheck to
    check my scripts and thought it might be a good choice to do this for
    the 2ff script.
    Not much had to be changed, because I was careful writing it, but still
    it won't hurt to but $TMP in double quotes.

diff --git a/2ff b/2ff
index a7a3aeb..07c7d46 100755
--- a/2ff
+++ b/2ff
@@ -5,17 +5,17 @@ if [ "$#" -ne 0 ]; then
 fi
 
 TMP=$(mktemp)
-cat > $TMP;
+cat > "$TMP";
 
-FORMAT=$(file -ib $TMP | cut -d ";" -f 1);
+FORMAT=$(file -ib "$TMP" | cut -d ";" -f 1);
 
 case "$FORMAT" in
-    image/png)  png2ff < $TMP; ret=$? ;;
-    image/jpeg) jpg2ff < $TMP; ret=$? ;;
-    *) convert $TMP png:- 2>/dev/null | png2ff 2>/dev/null; ret=$? ;;
+    image/png)  png2ff < "$TMP"; ret=$? ;;
+    image/jpeg) jpg2ff < "$TMP"; ret=$? ;;
+    *) convert "$TMP" png:- 2>/dev/null | png2ff 2>/dev/null; ret=$? ;;
 esac
 
-rm $TMP;
+rm "$TMP";
 
 if [ $ret -ne 0 ]; then
        printf "%s: failed to convert %s\n" "$0" "$FORMAT" >&2;