What Aia suggested is fine if you're using a system where /bin/sh is not a pure Bourne shell (as it is on Solaris systems) or a 1988 Korn shell (as it is on many AIX systems). But, in addition to what Aia already commented on, there is nothing in your script that sets the shell variable _infos, so, unless that variable is being inherited from an exported variable in the environment of your script, the $_infos in your invocations of curl will be replaced by an empty string by the shell each time it invokes curl.

When posting questions to these forums, it always helps us provide answers that will work better in your environment if you tell us what operating system and shell you're using when you post questions. And, if you're using shell variables that aren't defined in your script, please tell us where those variables are being initialized.

If you are using a Solaris system or an AIX system or an HP/UX system, you're likely to get a bunch of syntax errors from Aia's suggestion, and we'll need to know which OS you're using, whether we can use a shell other than /bin/sh on your system (such as /usr/xpg4/bin/sh on a Solaris system or /bin/ksh93 on AIX) so we'll know if we can just use a different shell or if we need to convert the shell substring expansion into a single awk script (if you're stuck with a pure Bourne shell) or into POSIX conforming variable expansions in other shells.