Linux/Unix command to determine if process is running?

Question

I need a platform independent (Linux/Unix|OSX) shell/bash command that will determine if a specific process is running. e.g. mysqld, httpd... What

Answer 1

None of the answers worked for me, so heres mine:

process="$(pidof YOURPROCESSHERE|tr -d '\n')"
if [[ -z "${process// }" ]]; then
  echo "Process is not running."
else
  echo "Process is running."
fi

Explanation:

|tr -d '\n'

This removes the carriage return created by the terminal. The rest can be explained by this post.