-eq 等于,如:if [“ a " − e q " a" -eq " a"−eq"b” ]
-ne 不等于,如:if [“ a " − n e " a" -ne " a"−ne"b” ]
-gt 大于,如:if [“ a " − g t " a" -gt " a"−gt"b” ]
-ge 大于等于,如:if [“ a " − g e " a" -ge " a"−ge"b” ]
-lt 小于,如:if [“ a " − l t " a" -lt " a"−lt"b” ]
-le 小于等于,如:if [“ a " − l e " a" -le " a"−le"b” ]
< 小于(需要双括号),如:((“ a " < " a" < " a"<"b”))
<= 小于等于(需要双括号),如:((“ a " < = " a" <= " a"<="b”))
大于(需要双括号),如:((“ a " > " a" > " a">"b”))
= 大于等于(需要双括号),如:((“ a " > = " a" >= " a">="b”))
另外：$?是shell变量,表示"最后一次执行命令"的退出状态.0为成功,非0为失败.
