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+# Shell functions can't be passed to external commands.
+
+### Problematic code:
+
+    foo() { rm /run/foo; bar --baz; };
+    sudo foo
+
+### Correct code:
+
+    sudo sh -c 'rm /run/foo; bar --baz;'
+
+### Rationale:
+
+Shell functions are only known to the shell. External commands like `xargs`, `su` and `sudo` do not recognize shell functions. 
+
+Instead, the function contents can be executed in a shell, either through `sh -c` or by creating a separate shell script as an executable file.
+
+### Contraindications
+
+None.
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