/usr/bin/ld: cannot find -lpthreads

This error message indicates that the linker (ld) cannot find the pthreads library (-lpthreads) that is needed to link your program.

To resolve this error, you need to ensure that the pthreads library is installed on your system and that the linker can find it. Here are some steps you can take:

1. Install the pthreads library:
On Ubuntu, you can install the library by running the following command:

   sudo apt-get install libpthread-stubs0-dev

On other Linux distributions, the package name may be different. You can search for the package using your package manager.

2. Check the library path:
Once the library is installed, you need to make sure that the linker can find it. You can check the library path using the following command:

   ldconfig -p | grep pthread

This will show you the location of the pthreads library.

3. Specify the library path:
If the library path is not included in the linker's search path, you can specify it using the -L option followed by the path to the library directory. For example:

   gcc -o myprogram myprogram.c -L/usr/lib/x86_64-linux-gnu -lpthreads

4. Check the spelling:
Make sure that you have spelled the library name correctly. It should be -lpthread (without the 's' at the end).

Once you have resolved the error, you should be able to compile and link your program successfully.