Strings are not quoted for test , though you may need to quote them to protect characters with special meaning to the shell, e.g., spaces. True if the length of string is zero. Numeric tests Numeric relationals. The usual logical connectives. Each token of the expression must be a separate argument.
Operands are either numbers or strings.
Strings are not quoted for expr , though you may need to quote them to protect characters with special meaning to the shell, e.g., spaces. Operators may given as infix symbols or prefix keywords. Relations for expr The usual logical connectives and relations, in order of precedence. Numeric expressions Numeric operators, in order of increasing precedence. String expressions String operators.