make shell scripts more POSIX-compatible, and use tabs instead of spaces

usr/bin/unzip-all

@@ -1,13 +1,14 @@
-#/bin/bash
+#!/usr/bin/sh
 
 if [ -z ${var+2} ]; then
-    echo -e "\033[91mno parameters were given!\033[0m"
+	printf "\033[91mno parameters were given!\033[0m\n"
 fi
 
 for i in $2; do
-    readonly fname="$(basename $i .*)"
-    mkdir "$fname"
-    cd "$fname"
-    unzip "../$i"
-    cd -
+	readonly fname
+	fname="$(basename "$i" .*)"
+	mkdir "$fname"
+	cd "$fname" || return 1
+	unzip "../$i"
+	cd - || return 1
 done