Created SC2078 (markdown)

SC2078.md

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+## This expression is constant. Did you forget a `$` somewhere?
+### Problematic code:
+
+```sh
+if [ "myvar" ]
+then
+  echo "myvar is set"
+fi
+```
+
+### Correct code:
+
+```sh
+if [ "$myvar" ]
+then
+  echo "myvar is set"
+fi
+```
+### Rationale:
+
+ShellCheck has found a `[ .. ]` or `[[ .. ]]` statement that just contains a literal string. Such a check does not do anything useful, and will always be true (or always false, for empty strings).
+
+This is usually due to missing `$` or bad quoting:
+
+    if [[ STY ]             # always true
+    if [[ $STY ]]           # checks variable $STY
+
+    if [[ 'grep foo bar' ]] # always true
+    if [[ `grep foo bar` ]] # checks grep output (poorly)
+    if grep -q foo bar      # checks for grep match (preferred)
+
+
+### Exceptions:
+
+None