gtags --version (return code: 0)
gtags (GNU GLOBAL) 6.5.7 Copyright (c) 1996-2017 Tama Communications Corporation License GPLv3+: GNU GPL version 3 or later <http://www.gnu.org/licenses/gpl.html> This is free software; you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
gtags --help (return code: 0)
Usage: gtags [-ciIOqvw][-d tag-file][-f file][dbpath] Options: --accept-dotfiles Accept files and directories whose names begin with a dot. By default, gtags ignores them. -c, --compact Make GTAGS in compact format. This option does not influence GRTAGS, because that is always made in compact format. --config[=name] Print the value of config variable name. If name is not specified then print all names and values. In addition to the variables listed in the ENVIRONMENT section, you can refer to install directories by read only variables: bindir, libdir, datadir, localstatedir and sysconfdir. -d, --dump tag-file Dump a tag file as text to the standard output. Output format is 'key<tab>data'. This is for debugging. --explain Explain handling files. -f, --file file Give a list of candidates of target files. Files which are not on the list are ignored. The argument file can be set to - to accept a list of files from the standard input. File names must be separated by newline. To make the list you may use find(1), which has rich options for selecting files. --gtagsconf file Set environment variable GTAGSCONF to file. --gtagslabel label Set environment variable GTAGSLABEL to label. -I, --idutils In addition to tag files, make ID database for idutils(1). -i, --incremental Update tag files incrementally. It's better to use global(1) with the -u command. -O, --objdir Use BSD-style objdir as the location of tag files. If $MAKEOBJDIRPREFIX directory exists, gtags creates $MAKEOBJDIRPREFIX/<current directory> directory and makes tag files in it. If dbpath is specified, this option is ignored. --single-update file Update tag files for a single file. It is considered that file was added, updated or deleted, and there is no change in other files. This option implies the -i option. --skip-unreadable Skip unreadable files. --sqlite3 Use Sqlite 3 API to make tag files. By default, BSD/DB 1.85 API is used. To use this option, you need to invoke configure script with --with-sqlite3 in the build phase. --statistics Print statistics information. -q, --quiet Quiet mode. -v, --verbose Verbose mode. -w, --warning Print warning messages. dbpath The directory in which tag files are generated. The default is the current directory. See also: GNU GLOBAL web site: http://www.gnu.org/software/global/