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在Windows中，命令提示符 (cmd. exe) 命令行字符串是有长度限制的，本文帮助你了解命令行中的字符串长度限制，以免你的批处理脚本踩坑。
（以下在Win10环境测试过）

字符串长度限制

可在命令提示符处使用的字符串的最大长度为 8191 个字符。

此限制适用于：

• 命令行
• 由其他进程继承的单个环境变量，例如 PATH 变量
• 所有环境变量扩展

如果使用命令提示符运行批处理文件，此限制也适用于批处理文件

示例

• 在命令行窗口中，单条命令总长度不能超过8190个字符：

set astr=teststring1teststring2teststring3teststring4teststring5teststring6teststring7teststring8teststring9teststring10teststring11teststring12teststring13teststring14teststring15teststring16teststring17teststring18teststring19teststring20teststring21teststring22teststring23teststring24teststring25teststring26teststring27teststring28teststring29teststring30teststring31teststring32teststring33teststring34teststring35teststring36teststring37teststring38teststring39teststring40teststring41teststring42teststring43teststring44teststring45teststring46teststring47teststring48teststring49teststring50teststring51teststring52teststring53teststring54teststring55teststring56teststring57teststring58teststring59teststring60teststring61teststring62teststring63teststring64teststring65teststring66teststring67teststring68teststring69teststring70teststring71teststring72teststring73teststring74teststring75teststring76teststring77teststring78teststring79teststring80teststring81teststring82teststring83teststring84teststring85teststring86teststring87teststring88teststring89teststring90teststring91teststring92teststring93teststring94teststring95teststring96teststring97teststring98teststring99teststring100teststring101teststring102teststring103teststring104teststring105teststring106teststring107teststring108teststring109teststring110teststring111teststring112teststring113teststring114teststring115teststring116teststring117teststring118teststring119teststring120teststring121teststring122teststring123teststring124teststring125teststring126teststring127teststring128teststring129teststring130teststring131teststring132teststring133teststring134teststring135teststring136teststring137teststring138teststring139teststring140teststring141teststring142teststring143teststring144teststring145teststring146teststring147teststring148teststring149teststring150teststring151teststring152teststring153teststring154teststring155teststring156teststring157teststring158teststring159teststring160teststring161teststring162teststring163teststring164teststring165teststring166teststring167teststring168teststring169teststring170teststring171teststring172teststring173teststring174teststring175teststring176teststring177teststring178teststring179teststring180teststring181teststring182teststring183teststring184teststring185teststring186teststring187teststring188teststring189teststring190teststring191teststring192teststring193teststring194teststring195teststring196teststring197teststring198teststring199teststring200teststring201teststring202teststring203teststring204teststring205teststring206teststring207teststring208teststring209teststring210teststring211teststring212teststring213teststring214teststring215teststring216teststring217teststring218teststring219teststring220teststring221teststring222teststring223teststring224teststring225teststring226teststring227teststring228teststring229teststring230teststring231teststring232teststring233teststring234teststring235teststring236teststring237teststring238teststring239teststring240teststring241teststring242teststring243teststring244teststring245teststring246teststring247teststring248teststring249teststring250teststring251teststring252teststring253teststring254teststring255teststring256teststring257teststring258teststring259teststring260teststring261teststring262teststring263teststring264teststring265teststring266teststring267teststring268teststring269teststring270teststring271teststring272teststring273teststring274teststring275teststring276teststring277teststring278teststring279teststring280teststring281teststring282teststring283teststring284teststring285teststring286teststring287teststring288teststring289teststring290teststring291teststring292teststring293teststring294teststring295teststring296teststring297teststring298teststring299teststring300teststring301teststring302teststring303teststring304teststring305teststring306teststring307teststring308teststring309teststring310teststring311teststring312teststring313teststring314teststring315teststring316teststring317teststring318teststring319teststring320teststring321teststring322teststring323teststring324teststring325teststring326teststring327teststring328teststring329teststring330teststring331teststring332teststring333teststring334teststring335teststring336teststring337teststring338teststring339teststring340teststring341teststring342teststring343teststring344teststring345teststring346teststring347teststring348teststring349teststring350teststring351teststring352teststring353teststring354teststring355teststring356teststring357teststring358teststring359teststring360teststring361teststring362teststring363teststring364teststring365teststring366teststring367teststring368teststring369teststring370teststring371teststring372teststring373teststring374teststring375teststring376teststring377teststring378teststring379teststring380teststring381teststring382teststring383teststring384teststring385teststring386teststring387teststring388teststring389teststring390teststring391teststring392teststring393teststring394teststring395teststring396teststring397teststring398teststring399teststring400teststring401teststring402teststring403teststring404teststring405teststring406teststring407teststring408teststring409teststring410teststring411teststring412teststring413teststring414teststring415teststring416teststring417teststring418teststring419teststring420teststring421teststring422teststring423teststring424teststring425teststring426teststring427teststring428teststring429teststring430teststring431teststring432teststring433teststring434teststring435teststring436teststring437teststring438teststring439teststring440teststring441teststring442teststring443teststring444teststring445teststring446teststring447teststring448teststring449teststring450teststring451teststring452teststring453teststring454teststring455teststring456teststring457teststring458teststring459teststring460teststring461teststring462teststring463teststring464teststring465teststring466teststring467teststring468teststring469teststring470teststring471teststring472teststring473teststring474teststring475teststring476teststring477teststring478teststring479teststring480teststring481teststring482teststring483teststring484teststring485teststring486teststring487teststring488teststring489teststring490teststring491teststring492teststring493teststring494teststring495teststring496teststring497teststring498teststring499teststring500teststring501teststring502teststring503teststring504teststring505teststring506teststring507teststring508teststring509teststring510teststring511teststring512teststring513teststring514teststring515teststring516teststring517teststring518teststring519teststring520teststring521teststring522teststring523teststring524teststring525teststring526teststring527teststring528teststring529teststring530teststring531teststring532teststring533teststring534teststring535teststring536teststring537teststring538teststring539teststring540teststring541teststring542teststring543teststring544teststring545teststring546teststring547teststring548teststring549teststring550teststring551teststring552teststring553teststring554teststring555teststring556teststring557teststring558teststring559teststring560teststring561teststring562teststring563teststring564teststring565teststring566teststring567teststring568teststring569teststring570teststring571teststring572teststring573teststring574teststring575teststring576teststring577teststring578teststring579teststring580teststring581teststring582teststring583teststring584teststring585teststring586teststring587teststring588teststring589teststring590teststring591teststring592teststring593teststring594teststring595teststring596teststring597teststring598teststring599teststring600teststring601teststring602teststring603teststring604teststring605teststring606teststring607teststring608teststring609teststring610teststring611teststring612teststring613teststring614teststring615teststring616teststring617teststring618teststring619teststring620teststring621teststring622teststring623teststring624teststring625teststring626teststring627teststring628teststring629teststring630teststring631teststring632teststring633teststring634teststring635teststring636teststring637teststri

注意：官网说是不能超过8191个，我测试发现，最多8190个，第8191个无法输入，可能是闪烁的光标占了一个字符吧。

• 在批处理文件中，单条命令总长度可以超过 8191 个字符：

@echo off
set astr=teststring1teststring2teststring3teststring4teststring5teststring6teststring7teststring8teststring9teststring10teststring11teststring12teststring13teststring14teststring15teststring16teststring17teststring18teststring19teststring20teststring21teststring22teststring23teststring24teststring25teststring26teststring27teststring28teststring29teststring30teststring31teststring32teststring33teststring34teststring35teststring36teststring37teststring38teststring39teststring40teststring41teststring42teststring43teststring44teststring45teststring46teststring47teststring48teststring49teststring50teststring51teststring52teststring53teststring54teststring55teststring56teststring57teststring58teststring59teststring60teststring61teststring62teststring63teststring64teststring65teststring66teststring67teststring68teststring69teststring70teststring71teststring72teststring73teststring74teststring75teststring76teststring77teststring78teststring79teststring80teststring81teststring82teststring83teststring84teststring85teststring86teststring87teststring88teststring89teststring90teststring91teststring92teststring93teststring94teststring95teststring96teststring97teststring98teststring99teststring100teststring101teststring102teststring103teststring104teststring105teststring106teststring107teststring108teststring109teststring110teststring111teststring112teststring113teststring114teststring115teststring116teststring117teststring118teststring119teststring120teststring121teststring122teststring123teststring124teststring125teststring126teststring127teststring128teststring129teststring130teststring131teststring132teststring133teststring134teststring135teststring136teststring137teststring138teststring139teststring140teststring141teststring142teststring143teststring144teststring145teststring146teststring147teststring148teststring149teststring150teststring151teststring152teststring153teststring154teststring155teststring156teststring157teststring158teststring159teststring160teststring161teststring162teststring163teststring164teststring165teststring166teststring167teststring168teststring169teststring170teststring171teststring172teststring173teststring174teststring175teststring176teststring177teststring178teststring179teststring180teststring181teststring182teststring183teststring184teststring185teststring186teststring187teststring188teststring189teststring190teststring191teststring192teststring193teststring194teststring195teststring196teststring197teststring198teststring199teststring200teststring201teststring202teststring203teststring204teststring205teststring206teststring207teststring208teststring209teststring210teststring211teststring212teststring213teststring214teststring215teststring216teststring217teststring218teststring219teststring220teststring221teststring222teststring223teststring224teststring225teststring226teststring227teststring228teststring229teststring230teststring231teststring232teststring233teststring234teststring235teststring236teststring237teststring238teststring239teststring240teststring241teststring242teststring243teststring244teststring245teststring246teststring247teststring248teststring249teststring250teststring251teststring252teststring253teststring254teststring255teststring256teststring257teststring258teststring259teststring260teststring261teststring262teststring263teststring264teststring265teststring266teststring267teststring268teststring269teststring270teststring271teststring272teststring273teststring274teststring275teststring276teststring277teststring278teststring279teststring280teststring281teststring282teststring283teststring284teststring285teststring286teststring287teststring288teststring289teststring290teststring291teststring292teststring293teststring294teststring295teststring296teststring297teststring298teststring299teststring300teststring301teststring302teststring303teststring304teststring305teststring306teststring307teststring308teststring309teststring310teststring311teststring312teststring313teststring314teststring315teststring316teststring317teststring318teststring319teststring320teststring321teststring322teststring323teststring324teststring325teststring326teststring327teststring328teststring329teststring330teststring331teststring332teststring333teststring334teststring335teststring336teststring337teststring338teststring339teststring340teststring341teststring342teststring343teststring344teststring345teststring346teststring347teststring348teststring349teststring350teststring351teststring352teststring353teststring354teststring355teststring356teststring357teststring358teststring359teststring360teststring361teststring362teststring363teststring364teststring365teststring366teststring367teststring368teststring369teststring370teststring371teststring372teststring373teststring374teststring375teststring376teststring377teststring378teststring379teststring380teststring381teststring382teststring383teststring384teststring385teststring386teststring387teststring388teststring389teststring390teststring391teststring392teststring393teststring394teststring395teststring396teststring397teststring398teststring399teststring400teststring401teststring402teststring403teststring404teststring405teststring406teststring407teststring408teststring409teststring410teststring411teststring412teststring413teststring414teststring415teststring416teststring417teststring418teststring419teststring420teststring421teststring422teststring423teststring424teststring425teststring426teststring427teststring428teststring429teststring430teststring431teststring432teststring433teststring434teststring435teststring436teststring437teststring438teststring439teststring440teststring441teststring442teststring443teststring444teststring445teststring446teststring447teststring448teststring449teststring450teststring451teststring452teststring453teststring454teststring455teststring456teststring457teststring458teststring459teststring460teststring461teststring462teststring463teststring464teststring465teststring466teststring467teststring468teststring469teststring470teststring471teststring472teststring473teststring474teststring475teststring476teststring477teststring478teststring479teststring480teststring481teststring482teststring483teststring484teststring485teststring486teststring487teststring488teststring489teststring490teststring491teststring492teststring493teststring494teststring495teststring496teststring497teststring498teststring499teststring500teststring501teststring502teststring503teststring504teststring505teststring506teststring507teststring508teststring509teststring510teststring511teststring512teststring513teststring514teststring515teststring516teststring517teststring518teststring519teststring520teststring521teststring522teststring523teststring524teststring525teststring526teststring527teststring528teststring529teststring530teststring531teststring532teststring533teststring534teststring535teststring536teststring537teststring538teststring539teststring540teststring541teststring542teststring543teststring544teststring545teststring546teststring547teststring548teststring549teststring550teststring551teststring552teststring553teststring554teststring555teststring556teststring557teststring558teststring559teststring560teststring561teststring562teststring563teststring564teststring565teststring566teststring567teststring568teststring569teststring570teststring571teststring572teststring573teststring574teststring575teststring576teststring577teststring578teststring579teststring580teststring581teststring582teststring583teststring584teststring585teststring586teststring587teststring588teststring589teststring590teststring591teststring592teststring593teststring594teststring595teststring596teststring597teststring598teststring599teststring600teststring601teststring602teststring603teststring604teststring605teststring606teststring607teststring608teststring609teststring610teststring611teststring612teststring613teststring614teststring615teststring616teststring617teststring618teststring619teststring620teststring621teststring622teststring623teststring624teststring625teststring626teststring627teststring628teststring629teststring630teststring631teststring632teststring633teststring634teststring635teststring636teststring637teststring638tests
echo.%astr:~-10%
pause

1. 第2行，总共有8200个字符，set astr=占9个字符，值占8191个字符，这条命令总长度超过了8191字符？？？；
2. 第3行，echo输出astr变量的后10个字符。执行该批处理，会输出 ng638tests，但是有意思的是，当你把echo off改为echo on，再运行该批处理，你会发现，屏幕上显示出来的第2行命令 最后的10个字符串是ststring63，而且你还会发现，屏幕上第2行共总显示的命令是 8194个字符。

• 在命令行窗口中，展开变量后的命令行总长度不能超过8191个：

set astr=teststring1teststring2teststring3teststring4teststring5teststring6teststring7teststring8teststring9teststring10teststring11teststring12teststring13teststring14teststring15teststring16teststring17teststring18teststring19teststring20teststring21teststring22teststring23teststring24teststring25teststring26teststring27teststring28teststring29teststring30teststring31teststring32teststring33teststring34teststring35teststring36teststring37teststring38teststring39teststring40teststring41teststring42teststring43teststring44teststring45teststring46teststring47teststring48teststring49teststring50teststring51teststring52teststring53teststring54teststring55teststring56teststring57teststring58teststring59teststring60teststring61teststring62teststring63teststring64teststring65teststring66teststring67teststring68teststring69teststring70teststring71teststring72teststring73teststring74teststring75teststring76teststring77teststring78teststring79teststring80teststring81teststring82teststring83teststring84teststring85teststring86teststring87teststring88teststring89teststring90teststring91teststring92teststring93teststring94teststring95teststring96teststring97teststring98teststring99teststring100teststring101teststring102teststring103teststring104teststring105teststring106teststring107teststring108teststring109teststring110teststring111teststring112teststring113teststring114teststring115teststring116teststring117teststring118teststring119teststring120teststring121teststring122teststring123teststring124teststring125teststring126teststring127teststring128teststring129teststring130teststring131teststring132teststring133teststring134teststring135teststring136teststring137teststring138teststring139teststring140teststring141teststring142teststring143teststring144teststring145teststring146teststring147teststring148teststring149teststring150teststring151teststring152teststring153teststring154teststring155teststring156teststring157teststring158teststring159teststring160teststring161teststring162teststring163teststring164teststring165teststring166teststring167teststring168teststring169teststring170teststring171teststring172teststring173teststring174teststring175teststring176teststring177teststring178teststring179teststring180teststring181teststring182teststring183teststring184teststring185teststring186teststring187teststring188teststring189teststring190teststring191teststring192teststring193teststring194teststring195teststring196teststring197teststring198teststring199teststring200teststring201teststring202teststring203teststring204teststring205teststring206teststring207teststring208teststring209teststring210teststring211teststring212teststring213teststring214teststring215teststring216teststring217teststring218teststring219teststring220teststring221teststring222teststring223teststring224teststring225teststring226teststring227teststring228teststring229teststring230teststring231teststring232teststring233teststring234teststring235teststring236teststring237teststring238teststring239teststring240teststring241teststring242teststring243teststring244teststring245teststring246teststring247teststring248teststring249teststring250teststring251teststring252teststring253teststring254teststring255teststring256teststring257teststring258teststring259teststring260teststring261teststring262teststring263teststring264teststring265teststring266teststring267teststring268teststring269teststring270teststring271teststring272teststring273teststring274teststring275teststring276teststring277teststring278teststring279teststring280teststring281teststring282teststring283teststring284teststring285teststring286teststring287teststring288teststring289teststring290teststring291teststring292teststring293teststring294teststring295teststring296teststring297teststring298teststring299teststring300teststring301teststring302teststring303teststring304teststring305teststring306teststring307teststring308teststring309teststring310teststring311teststring312teststring313teststring314teststring315teststring316teststring317teststring318teststring319teststring320teststring321teststring322teststring323teststring324teststring325teststring326teststring327teststring328teststring329teststring330teststring331teststring332teststring333teststring334teststring335teststring336teststring337teststring338teststring339teststring340teststring341teststring342teststring343teststring344teststring345teststring346teststring347teststring348teststring349teststring350teststring351teststring352teststring353teststring354teststring355teststring356teststring357teststring358teststring359teststring360teststring361teststring362teststring363teststring364teststring365teststring366teststring367teststring368teststring369teststring370teststring371teststring372teststring373teststring374teststring375teststring376teststring377teststring378teststring379teststring380teststring381teststring382teststring383teststring384teststring385teststring386teststring387teststring388teststring389teststring390teststring391teststring392teststring393teststring394teststring395teststring396teststring397teststring398teststring399teststring400teststring401teststring402teststring403teststring404teststring405teststring406teststring407teststring408teststring409teststring410teststring411teststring412teststring413teststring414teststring415teststring416teststring417teststring418teststring419teststring420teststring421teststring422teststring423teststring424teststring425teststring426teststring427teststring428teststring429teststring430teststring431teststring432teststring433teststring434teststring435teststring436teststring437teststring438teststring439teststring440teststring441teststring442teststring443teststring444teststring445teststring446teststring447teststring448teststring449teststring450teststring451teststring452teststring453teststring454teststring455teststring456teststring457teststring458teststring459teststring460teststring461teststring462teststring463teststring464teststring465teststring466teststring467teststring468teststring469teststring470teststring471teststring472teststring473teststring474teststring475teststring476teststring477teststring478teststring479teststring480teststring481teststring482teststring483teststring484teststring485teststring486teststring487teststring488teststring489teststring490teststring491teststring492teststring493teststring494teststring495teststring496teststring497teststring498teststring499teststring500teststring501teststring502teststring503teststring504teststring505teststring506teststring507teststring508teststring509teststring510teststring511teststring512teststring513teststring514teststring515teststring516teststring517teststring518teststring519teststring520teststring521teststring522teststring523teststring524teststring525teststring526teststring527teststring528teststring529teststring530teststring531teststring532teststring533teststring534teststring535teststring536teststring537teststring538teststring539teststring540teststring541teststring542teststring543teststring544teststring545teststring546teststring547teststring548teststring549teststring550teststring551teststring552teststring553teststring554teststring555teststring556teststring557teststring558teststring559teststring560teststring561teststring562teststring563teststring564teststring565teststring566teststring567teststring568teststring569teststring570teststring571teststring572teststring573teststring574teststring575teststring576teststring577teststring578teststring579teststring580teststring581teststring582teststring583teststring584teststring585teststring586teststring587teststring588teststring589teststring590teststring591teststring592teststring593teststring594teststring595teststring596teststring597teststring598teststring599teststring600teststring601teststring602teststring603teststring604teststring605teststring606teststring607teststring608teststring609teststring610teststring611teststring612teststring613teststring614teststring615teststring616teststring617teststring618teststring619teststring620teststring621teststring622teststring623teststring624teststring625teststring626teststring627teststring628teststring629teststring630teststring631teststring632teststring633teststring634teststring635teststring636teststring637teststri
echo.123456%astr%

1. 先使用set命令，给astr变量中存放了8181个字符
2. 然后使用echo命令进行输出，echo.123456共11个字符，%astr%替换为实际字符串后，该命令行共有8181+11=8192个字符，运行时报错。但改为echo.12345%astr%，即去掉一个字符，则正常输出。所以展开变量后的命令行字符串总长度不能超过8191个

• 在批处理文件中，展开变量后的命令行总长度不超过8191个字符：

@echo off
set astr=teststring1teststring2teststring3teststring4teststring5teststring6teststring7teststring8teststring9teststring10teststring11teststring12teststring13teststring14teststring15teststring16teststring17teststring18teststring19teststring20teststring21teststring22teststring23teststring24teststring25teststring26teststring27teststring28teststring29teststring30teststring31teststring32teststring33teststring34teststring35teststring36teststring37teststring38teststring39teststring40teststring41teststring42teststring43teststring44teststring45teststring46teststring47teststring48teststring49teststring50teststring51teststring52teststring53teststring54teststring55teststring56teststring57teststring58teststring59teststring60teststring61teststring62teststring63teststring64teststring65teststring66teststring67teststring68teststring69teststring70teststring71teststring72teststring73teststring74teststring75teststring76teststring77teststring78teststring79teststring80teststring81teststring82teststring83teststring84teststring85teststring86teststring87teststring88teststring89teststring90teststring91teststring92teststring93teststring94teststring95teststring96teststring97teststring98teststring99teststring100teststring101teststring102teststring103teststring104teststring105teststring106teststring107teststring108teststring109teststring110teststring111teststring112teststring113teststring114teststring115teststring116teststring117teststring118teststring119teststring120teststring121teststring122teststring123teststring124teststring125teststring126teststring127teststring128teststring129teststring130teststring131teststring132teststring133teststring134teststring135teststring136teststring137teststring138teststring139teststring140teststring141teststring142teststring143teststring144teststring145teststring146teststring147teststring148teststring149teststring150teststring151teststring152teststring153teststring154teststring155teststring156teststring157teststring158teststring159teststring160teststring161teststring162teststring163teststring164teststring165teststring166teststring167teststring168teststring169teststring170teststring171teststring172teststring173teststring174teststring175teststring176teststring177teststring178teststring179teststring180teststring181teststring182teststring183teststring184teststring185teststring186teststring187teststring188teststring189teststring190teststring191teststring192teststring193teststring194teststring195teststring196teststring197teststring198teststring199teststring200teststring201teststring202teststring203teststring204teststring205teststring206teststring207teststring208teststring209teststring210teststring211teststring212teststring213teststring214teststring215teststring216teststring217teststring218teststring219teststring220teststring221teststring222teststring223teststring224teststring225teststring226teststring227teststring228teststring229teststring230teststring231teststring232teststring233teststring234teststring235teststring236teststring237teststring238teststring239teststring240teststring241teststring242teststring243teststring244teststring245teststring246teststring247teststring248teststring249teststring250teststring251teststring252teststring253teststring254teststring255teststring256teststring257teststring258teststring259teststring260teststring261teststring262teststring263teststring264teststring265teststring266teststring267teststring268teststring269teststring270teststring271teststring272teststring273teststring274teststring275teststring276teststring277teststring278teststring279teststring280teststring281teststring282teststring283teststring284teststring285teststring286teststring287teststring288teststring289teststring290teststring291teststring292teststring293teststring294teststring295teststring296teststring297teststring298teststring299teststring300teststring301teststring302teststring303teststring304teststring305teststring306teststring307teststring308teststring309teststring310teststring311teststring312teststring313teststring314teststring315teststring316teststring317teststring318teststring319teststring320teststring321teststring322teststring323teststring324teststring325teststring326teststring327teststring328teststring329teststring330teststring331teststring332teststring333teststring334teststring335teststring336teststring337teststring338teststring339teststring340teststring341teststring342teststring343teststring344teststring345teststring346teststring347teststring348teststring349teststring350teststring351teststring352teststring353teststring354teststring355teststring356teststring357teststring358teststring359teststring360teststring361teststring362teststring363teststring364teststring365teststring366teststring367teststring368teststring369teststring370teststring371teststring372teststring373teststring374teststring375teststring376teststring377teststring378teststring379teststring380teststring381teststring382teststring383teststring384teststring385teststring386teststring387teststring388teststring389teststring390teststring391teststring392teststring393teststring394teststring395teststring396teststring397teststring398teststring399teststring400teststring401teststring402teststring403teststring404teststring405teststring406teststring407teststring408teststring409teststring410teststring411teststring412teststring413teststring414teststring415teststring416teststring417teststring418teststring419teststring420teststring421teststring422teststring423teststring424teststring425teststring426teststring427teststring428teststring429teststring430teststring431teststring432teststring433teststring434teststring435teststring436teststring437teststring438teststring439teststring440teststring441teststring442teststring443teststring444teststring445teststring446teststring447teststring448teststring449teststring450teststring451teststring452teststring453teststring454teststring455teststring456teststring457teststring458teststring459teststring460teststring461teststring462teststring463teststring464teststring465teststring466teststring467teststring468teststring469teststring470teststring471teststring472teststring473teststring474teststring475teststring476teststring477teststring478teststring479teststring480teststring481teststring482teststring483teststring484teststring485teststring486teststring487teststring488teststring489teststring490teststring491teststring492teststring493teststring494teststring495teststring496teststring497teststring498teststring499teststring500teststring501teststring502teststring503teststring504teststring505teststring506teststring507teststring508teststring509teststring510teststring511teststring512teststring513teststring514teststring515teststring516teststring517teststring518teststring519teststring520teststring521teststring522teststring523teststring524teststring525teststring526teststring527teststring528teststring529teststring530teststring531teststring532teststring533teststring534teststring535teststring536teststring537teststring538teststring539teststring540teststring541teststring542teststring543teststring544teststring545teststring546teststring547teststring548teststring549teststring550teststring551teststring552teststring553teststring554teststring555teststring556teststring557teststring558teststring559teststring560teststring561teststring562teststring563teststring564teststring565teststring566teststring567teststring568teststring569teststring570teststring571teststring572teststring573teststring574teststring575teststring576teststring577teststring578teststring579teststring580teststring581teststring582teststring583teststring584teststring585teststring586teststring587teststring588teststring589teststring590teststring591teststring592teststring593teststring594teststring595teststring596teststring597teststring598teststring599teststring600teststring601teststring602teststring603teststring604teststring605teststring606teststring607teststring608teststring609teststring610teststring611teststring612teststring613teststring614teststring615teststring616teststring617teststring618teststring619teststring620teststring621teststring622teststring623teststring624teststring625teststring626teststring627teststring628teststring629teststring630teststring631teststring632teststring633teststring634teststring635teststring636teststring637teststri
echo.123456%astr%
pause

1. 第2行，set命令给astr变量赋值了8181个字符
2. 第3行，echo.123456共11个字符，%astr%替换为实际字符串后，该命令行共有8181+11=8192个字符，运行该批处理文件，闪一下，无任何输出信息。但改为echo.12345%astr%，即去掉一个字符，再执行该批处理，正常。所以展开变量后的命令行字符串总长度不能超过8191个。

官网也给了示例：command-line-string-limitation

可以结合官网的示例，仔细体会下。

总结

1）set命令，给变量赋值时，变量最多能存放8191个字符。但是命令行长度set +变量名=+字符串值 总长度超过了8191个字符；
2）在命令行窗口上，单个命令行最多允许8190个字符（光标占了一个字符）；
3）echo命令，最多只能输出8186个字符（echo.本身占5个字符）；

多数情况下，你的脚本可能达不到这些限制，但保不齐哪天会掉到这个坑里，多了解些这些限制总不会有错吧

关于如何应对这些限制，官网也给了解决建议，自行查阅
如何解决限制问题