Created SC2238 (markdown)

SC2238.md

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+## Redirecting to/from command name instead of file. Did you want pipes/xargs (or quote to ignore)?
+
+### Problematic code:
+
+```sh
+cat file > tr -d '\r'
+cat file > rm
+```
+
+### Correct code:
+
+```sh
+cat file | tr -d '\r'         # tr reads stdin
+cat file | xargs -d '\n' rm   # rm reads arguments
+```
+
+### Rationale:
+
+You are using file redirection, but the filename is an unquoted command name. Instead of running the command and feeding data to it, this just writes to a file with the same name. 
+
+To run the command and feed data to it, determine how it gets its data:
+
+* If the command reads from STDIN, simply use a pipe as in the first example.
+* If the command reads multiple arguments, use a pipe to `xargs` as in the second example
+
+Note that `xargs` has many pitfalls when it comes to spaces and quotes. `cat file | xargs rm`  will appear to work during testing, but fails for filenames like `My File.txt` or `Can't_Fight_This_Feeling.mp3`. The example uses the GNU extension `-d '\n'` to more safely handle these names. 
+
+### Exceptions:
+
+If you actually did want to write a file named after a command, simply quote the filename to let ShellCheck know you meant it literally and not as a command name. This does not change anything about how the script works:
+
+```sh
+# Write to a file literally named 'rm', does not try to delete anything
+echo "A potentially dangerous command" > "rm" 
+```
+
+### Related resources:
+
+* Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!