opkg must have one sub-command argument
usage: opkg [options…] sub-command [arguments…]
where sub-command is one of:

Package Manipulation:
update Update list of available packages
upgrade Upgrade installed packages
install <pkgs> Install package(s)
configure <pkgs> Configure unpacked package(s)
remove <pkgs|regexp> Remove package(s)
flag <flag> <pkgs> Flag package(s)
<flag>=hold|noprune|user|ok|installed|unpacked (one per invocation)

Informational Commands:
list List available packages
list-installed List installed packages
list-upgradable List installed and upgradable packages
list-changed-conffiles List user modified configuration files
files <pkg> List files belonging to <pkg>
search <file|regexp> List package providing <file>
info [pkg|regexp] Display all info for <pkg>
status [pkg|regexp] Display all status for <pkg>
download <pkg> Download <pkg> to current directory
compare-versions <v1> <op> <v2>
compare versions using <= < > >= = << >>
print-architecture List installable package architectures
depends [-A] [pkgname|pat]+
whatdepends [-A] [pkgname|pat]+
whatdependsrec [-A] [pkgname|pat]+
whatrecommends[-A] [pkgname|pat]+
whatsuggests[-A] [pkgname|pat]+
whatprovides [-A] [pkgname|pat]+
whatconflicts [-A] [pkgname|pat]+
whatreplaces [-A] [pkgname|pat]+

Options:
-A Query all packages not just those installed
-V[<level>] Set verbosity level to <level>.
–verbosity[=<level>] Verbosity levels:
0 errors only
1 normal messages (default)
2 informative messages
3 debug
4 debug level 2
-f <conf_file> Use <conf_file> as the opkg configuration file
–conf <conf_file>
–cache <directory> Use a package cache
-d <dest_name> Use <dest_name> as the the root directory for
–dest <dest_name> package installation, removal, upgrading.
<dest_name> should be a defined dest name from
the configuration file, (but can also be a
directory name in a pinch).
-o <dir> Use <dir> as the root directory for
–offline-root <dir> offline installation of packages.
–add-arch <arch>:<prio> Register architecture with given priority
–add-dest <name>:<path> Register destination with given path
–add-exclude <name> Register package to be excluded from install
–prefer-arch-to-version Use the architecture priority package rather
than the higher version one if more
than one candidate is found.

Force Options:
–force-depends Install/remove despite failed dependencies
–force-maintainer Overwrite preexisting config files
–force-reinstall Reinstall package(s)
–force-overwrite Overwrite files from other package(s)
–force-downgrade Allow opkg to downgrade packages
–force-space Disable free space checks
–force-postinstall Run postinstall scripts even in offline mode
–force-remove Remove package even if prerm script fails
–noaction No action — test only
–download-only No action — download only
–nodeps Do not follow dependencies
–no-install-recommends
Do not install any recommended packages
–force-removal-of-dependent-packages
Remove package and all dependencies
–autoremove Remove packages that were installed
automatically to satisfy dependencies
-t Specify tmp-dir.
–tmp-dir Specify tmp-dir.

regexp could be something like ‘pkgname*’ ‘*file*’ or similar
e.g. opkg info ‘libstd*’ or opkg search ‘*libop*’ or opkg remove ‘libncur*’

opkg update 更新可以获取的软件包列表
opkg upgrade 对已经安装的软件包升级
opkg list 获取软件列表
opkg install 安装指定的软件包
opkg remove 卸载已经安装的指定的软件包