added shellcheck

sheets/shellcheck

@@ -0,0 +1,19 @@
+# shellcheck
+# Shell script static analysis tool.
+
+# Check a shell script:
+shellcheck file.sh
+
+# Override script's shebang:
+shellcheck --shell sh|bash|ksh file.sh
+
+# Ignore certain errors:
+shellcheck --exclude SC1009 file.sh
+
+# Ignore multiple errors:
+shellcheck --exclude SC1009,SC1073 file.sh
+
+# To disable some check, e.g. SC2034, for a statement in code
+# add comment with the following line
+# shellcheck disable=SC2034
+