Ubuntu - #include <curl/curl.h> no such file or directory

C compilers' (preprocessors', actually) standard include file searching paths should include /usr/include, therefore if the include file curl.h is located in /usr/include/curl/ and is included by #include <curl/curl.h>, C compilers, such as gcc, should be able to find it without any problem.

However, you are using a toolchain under /opt/toolchains/arm-2011.V2/bin, I guess it is a cross-compiling toolchain. In this case, you cannot use the curl library, because which is for the host system, which probably is a x86 or x86_64 system.

To use curl library in your ARM project, you need to install the curl library development package for ARM, if that is possible. If the software repositories do not have those packages, then you need to download the source code and cross-compile it for ARM first.

This fixed it for me:

sudo ln -s /usr/include/x86_64-linux-gnu/curl /usr/include/curl