Updated SC3004 (markdown)

SC3004.md

@@ -1 +1,35 @@
-# SC3004: In POSIX sh, $".." is undefined
+## In POSIX sh, $".." is undefined
+
+### Problematic code:
+
+```sh
+printf $"Hello, %s\n" "$USER"
+```
+
+### Correct code:
+
+```sh
+# Check if gettext exists
+if ! type gettext > /dev/null 2>&1
+then
+  # If not, create a dummy function that returns the input verbatim
+  gettext() { printf '%s' "$1"; }
+fi
+
+# Use gettext to get a translated version of the string
+printf "$(gettext 'Hello, %s\n')" "$USER"
+```
+
+### Rationale:
+
+Bash allows using `$"..."` to easily get a translated string according to the current locale. This is powered by the gettext infrastructure.
+
+Neither `$".."` nor the gettext infrastructure or the `gettext` command is POSIX. A script targeting `sh` may choose to invoke `gettext` if the system has it (such as GNU or Solaris), or use the translated string verbatim if it doesn't (such as macOS or FreeBSD).
+
+### Exceptions:
+
+None.
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!