usage()
{
    printf '%s\n' \
     "Qi is a simple but well-integrated package manager.  It can create,"                     \
     "install, remove, and upgrade software packages.  Qi produces binary"                     \
     "packages using recipes, which are files containing specific instructions"                \
     "to build each package from source.  Qi can manage multiple packages"                     \
     "under a single directory hierarchy.  This method allows to maintain a"                   \
     "set of packages and multiple versions of them.  This means that Qi could"                \
     "be used as the main package manager or complement the existing one."                     \
     ""                                                                                        \
     "Usage: $PROGRAM COMMAND [OPTIONS] [FILE]..."                                             \
     ""                                                                                        \
     "Defaults for the options are specified in brackets."                                     \
     ""                                                                                        \
     "List of commands:"                                                                       \
     "  warn                     Warn about files that will be installed"                      \
     "  install                  Install packages"                                             \
     "  remove                   Remove packages"                                              \
     "  upgrade                  Upgrade packages"                                             \
     "  extract                  Extract packages for debugging purposes"                      \
     "  create                   Create a .tlz package from directory"                         \
     "  build                    Build packages using recipe names"                            \
     "  order                    Resolve build order through .order files"                     \
     ""                                                                                        \
     "Options when installing, removing, or upgrading software packages:"                      \
     "  -f, --force              Force upgrade of pre-existing packages"                       \
     "  -k, --keep               Keep package directory when remove/upgrade"                   \
     "  -p, --prune              Prune conflicts"                                              \
     "  -P, --packagedir=<dir>   Set directory for package installations"                      \
     "  -t, --targetdir=<dir>    Set target directory for symbolic links"                      \
     "  -r, --rootdir=<dir>      Use the fully qualified named directory as"                   \
     "                           the root directory for all qi operations"                     \
     "                           Note: the target directory and the package"                   \
     "                           directory will be relative to the specified"                  \
     "                           directory, excepting the graft log file"                      \
     ""                                                                                        \
     "Options when building software packages using recipes:"                                  \
     "  -a, --architecture       Set architecture name for the package [${arch}]"              \
     "  -j, --jobs               Parallel jobs for the compiler [${jobs}]"                     \
     "  -k, --keep               Keep \`\${srcdir}' or \`\${destdir}' when build"              \
     "  -S, --skip-questions     Skip questions on completed recipes"                          \
     "  -1, --increment          Increment release number (\`\${release}' + 1)"                \
     "  -n, --no-package         Do not create a .tlz package"                                 \
     "  -i, --install            Install package after the build"                              \
     "  -u, --upgrade            Upgrade package after the build"                              \
     "  -o, --outdir=<dir>       Where the packages produced will be written [${outdir}]"      \
     "  -w, --worktree=<dir>     Where archives, patches, recipes are expected [${worktree}]"  \
     "  -s, --sourcedir=<dir>    Where compressed sources will be found [${tardir}]"           \
     ""                                                                                        \
     "Other options:"                                                                          \
     "  -N, --no-rc              Do not read the configuration file"                           \
     "  -v, --verbose            Be verbose (an extra -v gives more) [${verbose}]"             \
     "  -L, --show-location      Print default directory locations and exit"                   \
     "  -h, --help               Display this help and exit"                                   \
     "  -V, --version            Output version information and exit"                          \
     ""                                                                                        \
     "Some influential environment variables:"                                                 \
     "  TMPDIR                   Temporary directory for sources [${TMPDIR}]"                  \
     "  QICFLAGS                 C compiler flags [${QICFLAGS}]"                               \
     "  QICXXFLAGS               C++ compiler flags [${QICXXFLAGS}]"                           \
     "  QILDFLAGS                Linker flags [${QILDFLAGS}]"                                  \
     ""                                                                                        \
     "When FILE is -, read standard input."                                                    \
     ""                                                                                        \
     "Exit status: 0 for a normal exit, 1 for minor common errors (help usage,"                \
     "support not available, etc), 2 to indicate a command execution error;"                   \
     "3 for integrity check error on compressed files, 4 for empty, not"                       \
     "regular, or expected files, 5 for empty or not defined variables,"                       \
     "6 when a package already exist, 10 for network manager errors."                          \
     ""                                                                                        \
     "Qi home page: https://www.dragora.org"
}