Bash脚本中的SED可将变量的内容复制到文件中

Question

I need to copy the content of a variable in the top of other file without deleting the text of the file.

I have this code:

var=$(<file.txt)
sed -i -e '1i$var' file2

But only writes the text "$var" in the first line of file2, not the total content of var.

Any idea?.

Thank you.

Answer 1

Use double quotes for shell to expand variables:

sed -i -e "1i$var" file2

btw you can avoid sed by using:

cat file.txt file2 > _tmp && mv _tmp file2

Answer 2

如果要在变量或多个变量后添加一些固定值，则必须在表达式周围使用双引号 ，在var周围使用大括号 。

sed -i "1s/^/${var}FIXEDTEXTHERE /" file2

Answer 3

cat file.txt <> file2

没有临时文件