Shell脚本传递带有变量的字符串，以便以后分配

Question

I am working on Mac OSX and using bash as my shell. I was wondering if there was any way to create a string with some marker in it, that would later be evaluated. Such as:

Str=$(printf '%d is %s' "5" (#some string I don't know yet) )

Later...

some string I don't know yet="something I know now"
echo Str               #produces: 5 is something I know now

I know this in most cases could be remedy by moving the order of where I am placing the variables, but in this case I would like the order to be as is. Or is this not even possible? Thanks for your help.

Answer 1

Sure, just use printf twice. The fist time, escape the %s so that it goes into the string as-is, and the second time use it as the format string.

Str=$(printf '%d is %%s' 5)
New="something I know now"
printf "${Str}" "${New}"