Created SC2207 (markdown)

SC2207.md

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+## Prefer mapfile or read -a to split command output (or quote to avoid splitting).
+
+### Problematic code:
+
+```sh
+array=( $(mycommand) )
+```
+
+### Correct code:
+
+If the output should be a single element:
+
+```sh
+array=( "$(mycommand)" )
+```
+
+If it outputs multiple lines, each of which should be an element:
+
+```sh
+# For bash
+mapfile -t array < <(mycommand)
+
+# For ksh
+mycommand | while IFS="" read -r line; do array+=("$line"); done
+```
+
+If it outputs a line with multiple words (separated by spaces, other delimiters can be chosen with IFS), each of which should be an element:
+
+```sh
+# For bash
+IFS=" " read -r -a array <<< "$(mycommand)"
+
+# For ksh
+IFS=" " read -r -A array <<< "$(mycommand)"
+```
+
+### Rationale:
+
+You are doing unquoted command expansion in an array. This will invoke the shell's sloppy word splitting and glob expansion.
+
+Instead, prefer explicitly splitting (or not splitting):
+
+* If the command output should become a single array element, quote it.
+* If you want to split the output into lines or words, use `mapfile`, `read -ra` and/or `while` loops as appropriate.
+
+This prevents the shell from doing unwanted splitting and glob expansion, and therefore avoiding problems with output containing spaces or special characters.
+
+### Exceptions:
+
+If you have already taken care (through setting IFS and `set -f`) to have word splitting work the way you intend, you can ignore this warning.