我想在if语句中测试一个bash函数返回值，如下所示：
if [[ func arg ]] ; then …
但我得到错误消息如：条件二元运算符。
什么是正确的方法这样做？
是吗：
if [[ $(func arg) ]] ; then ...
如果是退出代码，而不是结果，你可以使用
if func arg; then ...
如果你不能让函数返回一个合适的退出代码(返回N)，并且你必须使用字符串结果，使用@Alex Gitelman回答。
$ help if：
if: if COMMANDS; then COMMANDS; [ elif COMMANDS; then COMMANDS; ]... [ else COMMANDS; ] fiExecute commands based on conditional.
The
if COMMANDSlist is executed. If its exit status is zero,then the
then COMMANDSlist is executed. Otherwise,eachelif COMMANDSlist is
executed in turn,and if its exit status is zero,the corresponding
then COMMANDSlist is executed and the if command completes. Otherwise,
the `else COMMANDS’ list is executed,if present. The exit status of the
entire construct is the exit status of the last command executed,or zero
if no condition tested true.Exit Status: Returns the status of the last command executed.
