Executing linux aliases from sqlplus

In sqlplus there is an option to execute standard shell commands, simply by prefixing them with '!'. Example: SQL>!ps -af returns expected processes. My question is, is there an option to execute user defined aliases in the same way? So far I tried: 1. In .bash_profile: alias sample="ps -af". 2. In sqlplus SQL>!sample. This doesn't work. /bin/bash: sample: command not found.