Bash format string. Substitute placeholders with values.

Question

I would like to format string using linux bash:

"<username>{0}</username><password>{1}</password>".format("user", "pass")

Output:

<username>user</username><password>pass</password>

What is the correct command to do this? I can use any other wildcard instead {0} and {1}

Answer 1

From printf --help:

-v var    assign the output to shell variable VAR rather than display it on the standard output

So, what you need to do is just:

FMT='<username>%s</username><password>%s</password>'
printf -v VAR "$FMT" user pass