SC2059 and $$

[phs75]

The following code

printf "$$"
printf "$$%s" "foo"

triggers SC2059: Don't use variables in the printf format string. Use printf "..%s.." "$foo" for the 1st line, but not for the second. How come?

I run ShellCheck version: 0.6.0

[koalaman]

This is intended for people who use printf as if it was echo, e.g. printf "Hello $USER, the time is $(date)\n", without realizing that a major point of printf is to separate the format string and values.

If you do specify a format string with values, you're obviously already aware of this, so ShellCheck assumes that your mixing of template arguments and variable expansions was intentional.

I haven't actually checked whether this is a valid assumption, so that's worth looking into.

[matthewpersico]

I’d say if only instances of %s are in the format use echo. Printf for formatting implies right justify or length limiting or printing as a number. If your not doing any of those, use rxho

[koalaman]

printf does behave more predictably with respect to backslashes and dashes though

[phs75]

@koalaman Thanks for the explanation. I thought there was something special with $$. Should have done more tests and/or look at the code ...