方法/步骤 1 if命令3种基本用法，可以通在cmd中使用if /?来查看到。IF [NOT] ERRORLEVEL number comman IF [NOT] string1==string2 commandIF [NOT] EXIST filename command 2 if 条件表达式 (语句1) else (语句2)，条件表达式成立执行语句1，否则，将执行语句2；if语句几个常用的用法，判断驱动器、文件...
第二种用法:IF [NOT] string1==string2 command 第三种用法:IF [NOT] EXIST filename command IF增强的用法 IF [/I] string1 compare-op string2 command #参数/I表示不区分大小写 IF CMDEXTVERSION number command IF DEFINED variable command #判断变量是否存在,很有用 CMDEXTVERSION 条件的作用跟 ERRORLE...
SET str2 = String2 if defined str1 echo "Variable str1 is defined" if defined str3 (echo "Variable str3 is defined") else (echo "Variable str3 is not defined") 1. 2. 3. 4. 5. 6. 上面的命令产生以下输出。 "Variable str1 is defined" "Variable str3 is not defined" 1. 2. i...
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ifdefined <variable> [else<expression>] 参数 说明 not //指定仅当条件为 false 时才应执行该命令。 errorlevel <number> //仅当由 Cmd.exe 运行的上一个程序返回等于或大于 数字的退出代码时,才指定 true 条件。 //如果满足前面的条件,则指定应执行的命令。 <string1>==<string...
ifdefined变量 command 语句 #判断变量是否已经定义 iferrorlevel数值 command 语句 #判断上个命令的返回值 //如果if后面判断为真后,只处理单句命令的话,直接跟在后面就可以 ifexist d:\test.txt (echo D盘下有test.txt存在)else(echo D盘下不存在test.txt) ...
if [/i] <String1> <CompareOp> <String2> <Command> [else <Expression>] if cmdextversion <Number> <Command> [else <Expression>] if defined <Variable> <Command> [else <Expression>] Parameters Expand table Parameter Description not Specifies that the command should be carried out only if...
if [/i] <string1> <compareop> <string2> [else <expression>] if cmdextversion <number> [else <expression>] if defined <variable> [else <expression>] Parameters Expand table ParameterDescription not Specifies that the command should be carried out only if the condition is false. erro...
ERROR: Variable: found in expression: is not defined. ERROR:Cannot process argument transformation on parameter 'DriveLetter'. Cannot convert value "$DriveLetter" to type "System.Char". Error: "String must be exactly one character long." escape the single quote inside an insert statement Escapin...
if [not] exist FileName Command [else Expression] If command extensions are enabled, use the following syntax: if [/i] String1 CompareOp String2 Command [else Expression] if cmdextversion Number Command [else Expression] if defined Variable Command [else Expression] Parameters not Specifies that...