Create/update Jar file in Unix without affecting the Manifest.MF

Update a jar file :  jar -uf  <jar_name>  <path_to_file/folder to be updated>.
 The <Path_To_File> should be same as the path inside the jar file .

Update jar without affecting existing Manifest : 

jar  -cmf  META\-INF/MANIFEST.MF  <Jar_File_Name>  <Files_To_Be_Packed>