Running java antlr.Tool $* with /usr/share/java/antlr.jar appended to the CLASSPATH variable ANTLR Parser Generator Version 2.7.7 (20170602) 1989-2005 error: no grammar file specified

Running java antlr.Tool $* with /usr/share/java/antlr.jar appended to the CLASSPATH variable ANTLR Parser Generator Version 2.7.7 (20170602) 1989-2005 usage: java antlr.Tool [args] file.g -o outputDir specify output directory where all output generated. -glib superGrammar specify location of supergrammar file. -debug launch the ParseView debugger upon parser invocation. -html generate a html file from your grammar. -docbook generate a docbook sgml file from your grammar. -diagnostic generate a textfile with diagnostics. -trace have all rules call traceIn/traceOut. -traceLexer have lexer rules call traceIn/traceOut. -traceParser have parser rules call traceIn/traceOut. -traceTreeParser have tree parser rules call traceIn/traceOut. -h|-help|--help this message