95 lines
4.4 KiB
Markdown
95 lines
4.4 KiB
Markdown
# Clixon CLI
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* [CLIgen](#cligen)
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* [Command history](#history)
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* [Large spec designs](#large-specs)
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## CLIgen
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The Clixon CLI uses [CLIgen](http://github.com/clicon/cligen) best described by the [CLIgen tutorial](https://github.com/clicon/cligen/blob/master/cligen_tutorial.pdf). The [example](example) is also helpful.
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Clixon adds some features and structure to CLIgen which include:
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* A plugin framework for both textual CLI specifications(.cli) and object files (.so)
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* Object files contains compiled C functions referenced by callbacks in the CLI specification. For example, in the cli spec command: `a,fn()`, `fn` must exist oin the object file as a C function.
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* A CLI API struct is given in the plugin. See [example](example/README.md#plugins).
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* A CLI specification file is enhanced with the following CLIgen variables:
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* `CLICON_MODE`: A colon-separated list of CLIgen `modes`. The CLI spec in the file are added to _all_ modes specified in the list.
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* `CLICON_PROMPT`: A string describing the CLI prompt using a very simple format with: `%H`, `%U` and `%T`.
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* `CLICON_PLUGIN`: the name of the object file containing callbacks in this file.
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* Clixon generates a command syntax from the Yang specification that can be refernced as `@datamodel`. This is useful if you do not want to hand-craft CLI syntax for configuration syntax. Example:
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```
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set @datamodel, cli_set();
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merge @datamodel, cli_merge();
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create @datamodel, cli_create();
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show @datamodel, cli_show_auto("running", "xml");
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```
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The commands (eg `cli_set`) will be called with the first argument an api-path to the referenced object.
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* The CLIgen `treename` syntax does not work.
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## History
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Clixon CLI supports persistent command history. There are two CLI history related configuration options: `CLICON_CLI_HIST_FILE` with default value `~/.clixon_cli_history` and `CLICON_CLI_HIST_SIZE` with default value 300.
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The design is similar to bash history but is simpler in some respects:
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* The CLI loads/saves its complete history to a file on entry and exit, respectively
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* The size (number of lines) of the file is the same as the history in memory
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* Only the latest session dumping its history will survive (bash merges multiple session history).
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Further, tilde-expansion is supported and if history files are not found or lack appropriate access will not cause an exit but will be logged at debug level
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## Large specs
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CLIgen is designed to handle large specifications in runtime, but it may be
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difficult to handle large specifications from a design perspective.
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Here are some techniques and hints on how to reduce the complexity of large CLI specs:
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### Sub-modes
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The `CLICON_MODE` can be used to add the same syntax in multiple modes. For example, if you have major modes `configure`and `operation` and a set of commands that should be in both, you can add a sub-mode that will appear in both configure and operation mode.
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```
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CLICON_MODE="configure:operation";
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show("Show") routing("routing");
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```
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Note that CLI command trees are _merged_ so that show commands in other files are shown together. Thus, for example:
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```
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CLICON_MODE="operation:files";
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show("Show") files("files");
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```
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will result in both commands in the operation mode (not the others):
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```
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cli> show <TAB>
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routing files
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```
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### Sub-trees
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You can also use sub-trees and the the tree operator `@`. Every mode gets assigned a tree which can be referenced as `@name`. This tree can be either on the top-level or as a sub-tree. For example, create a specific sub-tree that is used as sub-trees in other modes:
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```
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CLICON_MODE="subtree";
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subcommand{
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a, a();
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b, b();
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}
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```
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then access that subtree from other modes:
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```
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CLICON_MODE="configure";
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main @subtree;
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other @subtree,c();
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```
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The configure mode will now use the same subtree in two different commands. Additionally, in the `other` command, the callbacks will be overwritten by `c`. That is, if `other a`, or `other b` is called, callback function `c`will be invoked.
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### C-preprocessor
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You can also add the C preprocessor as a first step. You can then define macros, include files, etc. Here is an example of a Makefile using cpp:
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```
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C_CPP = clispec_example1.cpp clispec_example2.cpp
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C_CLI = $(C_CPP:.cpp=.cli
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CLIS = $(C_CLI)
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all: $(CLIS)
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%.cli : %.cpp
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$(CPP) -P -x assembler-with-cpp $(INCLUDES) -o $@ $<
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```
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