SC2193

The arguments to this comparison can never be equal. Make sure your syntax is correct.

Problematic code:

[[ "{$var}" == "value" ]]      # Swapped around $ and {
[[ "$(cmd1) | cmd2" == "42" ]] # Ended with ) too soon
[[ "$var " == *.png ]]         # Trailing space

Correct code:

[[ "${var}" == "value" ]]      # Correct variable expansion
[[ "$(cmd1 | cmd2)" == "42" ]] # Correct command substitution
[[ "$var" == *.png ]]          # No trailing space

Rationale:

ShellCheck has determined that the two values you're comparing can never be equal.

Most of the time, this happens because of a syntax issue that introduced unintended literal characters into one of the arguments.

The left-hand side in the problematic examples will always contain (respectively) curly braces, pipe and trailing space. The right-hand sides are literal values and a pattern without trailing spaces, so they will never be equal. The statement is therefore useless, strongly indicating a bug.

Exceptions:

None.