question: public static String shell ( int uid , String context ) { String shell = "su" ; if ( ( context != null ) && isSELinuxEnforcing ( ) ) { String display = version ( false ) ; String internal = version ( true ) ; if ( ( display != null ) && ( internal != null ) && ( display . endsWith ( "SUPERSU" ) ) && ( Integer . valueOf ( internal ) >= 190 ) ) { shell = String . format ( Locale . ENGLISH , "%s --context %s" , shell , context ) ; } } if ( uid > 0 ) { shell = String . format ( Locale . ENGLISH , "%s %d" , shell , uid ) ; } return shell ; }
target:  Constructs a shell command to start a su shell using the supplied uid and SELinux context. This is can be an expensive operation, consider caching the result.