bash 在 sed 中展开变量
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Expand variables in sed
提问by abkrim
I need use sed into bash script, for add lines after any line numer of script with some pair of values (below work)
我需要在 bash 脚本中使用 sed，以便在具有一些值对的脚本的任何行号之后添加行（下面的工作）
sed -i.bak '14i\some_text=some_text' file
But I need on script bash (sh) for expand variables (below not work)
但是我需要脚本 bash (sh) 来扩展变量（下面不起作用）
sed -i.bak '$number_linei$var1=$var2' $var3
回答by Carl Norum
Just use double quotes instead of single quotes. You'll also need to use {}to delimit the number_linevariable correctly and escape the \, too.
只需使用双引号而不是单引号。您还需要使用{}来number_line正确分隔变量并转义\。
sed -i.bak "${number_line}i\$var1=$var2" $var3
I'd personally prefer to see allof the variables use the {}, ending up with something like:
我个人更喜欢看到所有变量都使用{}，最终得到如下结果：
sed -i.bak "${number_line}i\${var1}=${var2}" ${var3}
回答by Lev Levitsky
Change single quotes to double quotes:
将单引号改为双引号：
man bash:
man bash：
Enclosing characters in single quotes preserves the literal value of
each character within the quotes.
Enclosing characters in double quotes preserves the literal value of
all characters within the quotes, with the exception of $, `, \, and,
when history expansion is enabled, !. The characters $ and ` retain
their special meaning within double quotes.
