Created Sc2086 (markdown)

Sc2086.md

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+#Double quote to prevent globbing and word splitting.
+
+### Problematic code:
+    echo $1
+
+### Correct code:
+    echo "$1"
+
+### Rationale 
+The problematic code looks like "print the first argument". It's actually "Split the first argument by spaces, tabs and line feeds. Expand each of them as if it was a glob. Join all the resulting strings and filenames with spaces. Print the result."
+
+Quoting prevents word splitting and glob expansion, and prevents the script from breaking when input contains spaces, line feeds, glob characters and such.
+
+### Contraindications
+Sometimes you want to split on spaces, like when building a command line.
+
+    options="-j 5 -B"
+    make $options file
+
+Just quoting this doesn't work. Instead, you should have used an array:
+
+    options=(-j 5 -B)
+    make "${options[@]}" file
+
+To split on spaces but not perform glob expansion, Bash has a `set -f` to disable globbing.
+