Numeric relational operators. The arguments must be entirely numeric
(possibly negative), or the special expression -l string,
which evaluates to the length of string.
For example:
test -1 -gt -2 && echo yes
⇒ yes
test -l abc -gt 1 && echo yes
⇒ yes
test 0x100 -eq 1
error--> test: integer expression expected before -eq