> For the complete documentation index, see [llms.txt](https://freebsdfrau.gitbook.io/serious-shell-programming/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://freebsdfrau.gitbook.io/serious-shell-programming/shellcheck/bad-advice.md).

# Bad Advice

shellcheck doesn't always give the best advice. Here are some examples where you should ignore what shellcheck is saying.

Using printf with dynamic formats:

```
printf "DEBUG: $fmt${fmt:+\n}" "$@" >&${TERMINAL_STDOUT_PASSTHRU:-1}
       ^-- SC2059: Don't use variables in the printf format string. Use printf "..%s.." "$foo".
```

It is not always a mistake to use a variable in the format argument of printf. This should be ignored if you are using a dynamic format string.

Using parameter expansion inside the argument space of the `:` built-in:

```
: ${TERMINAL_STDOUT_PASSTHRU:=3}
  ^-- SC2086: Double quote to prevent globbing and word splitting.
```

This should be ignored because shellcheck isn't smart enough to understand that the expansion of the variable is ignored because it appears in the argument space of the `:` built-in. You do not need to add double-quotes as it suggests.

This same error pops up when you use a variable argument to the `return` builtin. return only accepts an integer argument and thus it would be of little use to quote the variable when you know it will only ever be a number. The warning about word splitting does not apply in the below situation:

```
[ "$__name" ] || return $FAILURE
                        ^-- SC2086: Double quote to prevent globbing and word splitting.
```

Rest assured, any instance of the following will suffer from the same bad advice:

```
return $SUCCESS
       ^-- SC2086: Double quote to prevent globbing and word splitting.
```

Using sub-shells in the argument space of the `export` built-in:

```
export UNAME_S="$( uname -s )" # Operating System (i.e. FreeBSD)
       ^-- SC2155: Declare and assign separately to avoid masking return values.
```

What shellcheck refers to as "return value" is actually the "exit status" of the sub-shell where `uname -s` appears. If you don't care about the error, it should not matter that you put the sub-shell in the argument space of another command.

Using continue inside a loop when inside a function