用于测试文件是否包含多个字符串的Bash脚本，否则添加缺少的字符串？

I'm attempting to make a post-install script for Ubuntu 13.04 so that when run it will automatically install my desired programs and apply my desired settings such as create aliases so that apt-get=apt-fast, wget=aria2c and sudo="sudo ". At the beginning of the script I have it set to check for the alias list and expand it for use within the script if it exists so that the aliases are used throughout the script versus the original commands. I'm attempting to make a post-install script fo