Base Command For Check Your Had Installed Program on Your Linux

Again, I m always forget about anything simple command on linux. but now I want to write in this blogs for my  daily notes.

1. Check what have install :   dpkg –l
2. Check and grep specific program :dpkg -l | grep <nameofprogram>
3. Check list of package not install but available in dpkg chache : dpkg -l "apache*"