when i try to run
dpkg --get-selections --print-avail  > install.txt
this command in Ubuntu 12.04 the following error generate :
dpkg: error: conflicting actions -p (--print-avail) and  (--get-selections)

Type dpkg --help for help about installing and deinstalling packages [*];
Use `dselect' or `aptitude' for user-friendly package management;
Type dpkg -Dhelp for a list of dpkg debug flag values;
Type dpkg --force-help for a list of forcing options;
Type dpkg-deb --help for help about manipulating *.deb files;
i want to retrieve all detailed information about installed packackages like synaptic manager using command