From Mark Hammond: Improve usage message.

diff --git a/gpsbabel/main.c b/gpsbabel/main.c
index 82ec89d89678c65e4fe27a5d32c0d6a9dc989adf..704336c45cf960651587108f969d9a571195d5af 100644 (file)
--- a/gpsbabel/main.c
+++ b/gpsbabel/main.c
@@ -41,6 +41,11 @@ usage(const char *pname)
 "      In the second form of the command, INFILE and OUTFILE are the\n"
 "      first and second positional (non-option) arguments.\n"
 "\n"
+"      INTYPE and OUTTYPE must be one of the file types listed below, and\n"
+"      may include options valid for that file type.  For example:\n"
+"        'gpx', 'gpx,snlen=10' and 'ozi,snlen=10,snwhite=1'\n"
+"      (without the quotes) are all valid file type specifications.\n"
+"\n"
 "Options:\n"
 "      -s              Synthesize shortnames\n"
 "      -r              Process route information\n"
@@ -76,6 +81,8 @@ main(int argc, char *argv[])
        char *ovec_opts = NULL;
        char *fvec_opts = NULL;
        int opt_version = 0;
+       int did_something = 0;
+       const char *prog_name = argv[0]; /* argv is modified during processing */
 
        global_opts.objective = wptdata;
 
@@ -136,6 +143,7 @@ main(int argc, char *argv[])
                                ivecs->rd_init(fname);
                                ivecs->read();
                                ivecs->rd_deinit();
+                               did_something = 1;
                                break;
                        case 'F':
                                optarg = argv[argn][2]
@@ -205,6 +213,7 @@ main(int argc, char *argv[])
                fatal ("Extra arguments on command line\n");
        }
        else if (argc && ivecs) {
+               did_something = 1;
                ivecs->rd_init(argv[0]);
                ivecs->read();
                ivecs->rd_deinit();
@@ -215,18 +224,20 @@ main(int argc, char *argv[])
                }
        }
        else if (argc) {
-               usage(argv[0]);
+               usage(prog_name);
                exit(0);
        }
        if (ovecs == NULL)
                waypt_disp_all(waypt_disp);
 
+       if (!did_something)
+               fatal ("Nothing to do!  Use '%s -h' for command-line options.\n", prog_name);
+
        waypt_flush_all();
        route_flush_all();
 
 #ifdef DEBUG_MEM
        debug_mem_close();
 #endif
-       
        exit(0);
 }