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//! # Rust command-line library //! //! Common rust command-line macros and utilities, to write shell-script like tasks //! easily in rust programming language. Available at [crates.io](https://crates.io/crates/cmd_lib). //! //! ## Why you need this //! If you need to run some external commands in rust, the //! [std::process::Command](https://doc.rust-lang.org/std/process/struct.Command.html) is a good //! abstraction layer on top of different OS syscalls. It provides fine-grained control over //! how a new process should be spawned, and it allows you to wait for process to finish and check the //! exit status or collect all of its output. However, when //! [Redirection](https://en.wikipedia.org/wiki/Redirection_(computing)) or //! [Piping](https://en.wikipedia.org/wiki/Redirection_(computing)#Piping) is needed, you need to //! set up the parent and child IO handles manually, like this in the //! [rust cookbook](https://rust-lang-nursery.github.io/rust-cookbook/os/external.html), which is often a tedious //! work. //! //! A lot of developers just choose shell(sh, bash, ...) scripts for such tasks, by using `<` to redirect input, //! `>` to redirect output and '|' to pipe outputs. In my experience, this is **the only good parts** of shell script. //! You can find all kinds of pitfalls and mysterious tricks to make other parts of shell script work. As the shell //! scripts grow, they will ultimately be unmaintainable and no one wants to touch them any more. //! //! This cmd_lib library is trying to provide the redirection and piping capabilities, and other facilities to make writing //! shell-script like tasks easily **without launching any shell**. For the //! [rust cookbook examples](https://rust-lang-nursery.github.io/rust-cookbook/os/external.html), //! they can usually be implemented as one line of rust macro with the help of this library, as in the //! [examples/rust_cookbook_external.rs](https://github.com/rust-shell-script/rust_cmd_lib/blob/master/examples/rust_cookbook_external.rs). //! Since they are rust code, you can always rewrite them in rust natively in the future, if necessary without spawning external commands. //! //! ## What this library provides //! //! ### Macros to run external commands //! - run_cmd! --> CmdResult //! //! ``` //! # use cmd_lib::run_cmd; //! let msg = "I love rust"; //! run_cmd!(echo $msg)?; //! run_cmd!(echo "This is the message: $msg")?; //! //! // pipe commands are also supported //! run_cmd!(du -ah . | sort -hr | head -n 10)?; //! //! // or a group of commands //! // if any command fails, just return Err(...) //! let file = "/tmp/f"; //! let keyword = "rust"; //! if run_cmd! { //! cat ${file} | grep ${keyword}; //! echo "bad cmd" >&2; //! ls /nofile || true; //! date; //! ls oops; //! cat oops; //! }.is_err() { //! // your error handling code //! } //! # Ok::<(), std::io::Error>(()) //! ``` //! //! - run_fun! --> FunResult //! //! ``` //! # use cmd_lib::run_fun; //! let version = run_fun!(rustc --version)?; //! eprintln!("Your rust version is {}", version); //! //! // with pipes //! let n = run_fun!(echo "the quick brown fox jumped over the lazy dog" | wc -w)?; //! eprintln!("There are {} words in above sentence", n); //! # Ok::<(), std::io::Error>(()) //! ``` //! //! ### Abstraction without overhead //! Since all the macros' lexical analysis and syntactic analysis happen at compile time, it can //! basically generate code the same as calling `std::process` APIs manually. It also includes //! command type checking, so most of the errors can be found at compile time instead of at //! runtime. //! //! ### Intuitive parameters passing //! When passing parameters to `run_cmd!` and `run_fun!` macros, if they are not part to rust //! [String literals](https://doc.rust-lang.org/reference/tokens.html#string-literals), they will be //! converted to string as an atomic component, so you don't need to quote them. The parameters will be //! like $a or ${a} in `run_cmd!` or `run_fun!` macros. //! //! ``` //! # use cmd_lib::run_cmd; //! let dir = "my folder"; //! run_cmd!(echo "Creating $dir at /tmp")?; //! run_cmd!(mkdir -p /tmp/$dir)?; //! //! // or with group commands: //! let dir = "my folder"; //! run_cmd!(echo "Creating $dir at /tmp"; mkdir -p /tmp/$dir)?; //! # Ok::<(), std::io::Error>(()) //! ``` //! You can consider "" as glue, so everything inside the quotes will be treated as a single atomic component. //! //! If they are part of [Raw string literals](https://doc.rust-lang.org/reference/tokens.html#raw-string-literals), //! there will be no string interpolation, the same as in idiomatic rust. However, you can always use `format!` macro //! to form the new string. For example: //! ```no_run //! # use cmd_lib::run_cmd; //! // string interpolation //! let key_word = "time"; //! let awk_opts = format!(r#"/{}/ {{print $(NF-3) " " $(NF-1) " " $NF}}"#, key_word); //! run_cmd!(ping -c 10 www.google.com | awk $awk_opts)?; //! # Ok::<(), std::io::Error>(()) //! ``` //! //! If you want to use dynamic parameters, you can use $[] to access vector variable: //! ```no_run //! # use cmd_lib::run_cmd; //! let gopts = vec![vec!["-l", "-a", "/"], vec!["-a", "/var"]]; //! for opts in gopts { //! run_cmd!(ls $[opts])?; //! } //! # Ok::<(), std::io::Error>(()) //! ``` //! //! ### Redirection and Piping //! Right now piping and stdin, stdout, stderr redirection are supported. Most parts are the same as in //! [bash scripts](https://www.gnu.org/software/bash/manual/html_node/Redirections.html#Redirections). //! See examples at [examples/redirect.rs](https://github.com/rust-shell-script/rust_cmd_lib/blob/master/examples/redirect.rs) //! //! ### Builtin commands //! #### cd //! cd: set process current directory, which is always enabled //! ```no_run //! # use cmd_lib::run_cmd; //! run_cmd! ( //! cd /tmp; //! ls | wc -l; //! )?; //! # Ok::<(), std::io::Error>(()) //! ``` //! Notice that builtin `cd` will only change with current scope //! and it will restore the previous current directory when it //! exits the scope. //! //! Use `std::env::set_current_dir` if you want to change the current //! working directory for the whole program. //! //! #### true //! //! Just return true without launching any processes. //! //! #### echo //! //! ``` //! # use cmd_lib::{run_cmd, use_builtin_cmd}; //! use_builtin_cmd!(true, echo); // find more builtin commands in src/builtins.rs //! run_cmd!(echo "This is from builtin command!")?; //! # Ok::<(), std::io::Error>(()) //! ``` //! //! ### Macros to register your own commands //! Declare your function with `export_cmd` attribute: //! //! ``` //! # use cmd_lib::{export_cmd, use_custom_cmd, run_cmd, run_fun, CmdArgs, CmdEnvs, FunResult}; //! #[export_cmd(my_cmd)] //! fn foo(args: CmdArgs, _envs: CmdEnvs) -> FunResult { //! println!("msg from foo(), args: {:?}", args); //! Ok("bar".into()) //! } //! //! // To use it, just import it at first: //! use_custom_cmd!(my_cmd); //! run_cmd!(my_cmd)?; //! println!("get result: {}", run_fun!(my_cmd)?); //! # Ok::<(), std::io::Error>(()) //! ``` //! See examples in `examples/test_export_cmds.rs` //! //! ### Macros to define, get and set global variables //! - `proc_var!` to define thread local global variable //! - `proc_var_get!` to get the value //! - `proc_var_set!` to set the value //! ``` //! # use cmd_lib::{ proc_var, proc_var_get, proc_var_set }; //! proc_var!(DELAY, f64, 1.0); //! const DELAY_FACTOR: f64 = 0.8; //! proc_var_set!(DELAY, |d| *d *= DELAY_FACTOR); //! let d = proc_var_get!(DELAY); //! // check more examples in examples/tetris.rs //! ``` //! //! ## Other Notes //! //! ### Environment Variables //! //! You can use [std::env::var](https://doc.rust-lang.org/std/env/fn.var.html) to fetch the environment variable //! key from the current process. It will report error if the environment variable is not present, and it also //! includes other checks to avoid silent failures. //! //! To set environment variables for the command only, you can put the assignments before the command. //! Like this: //! ```no_run //! # use cmd_lib::run_cmd; //! run_cmd!(FOO=100 /tmp/test_run_cmd_lib.sh)?; //! # Ok::<(), std::io::Error>(()) //! ``` //! //! ### Security Notes //! Using macros can actually avoid command injection, since we do parsing before variable substitution. //! For example, below code is fine even without any quotes: //! ``` //! # use cmd_lib::{run_cmd, CmdResult}; //! fn cleanup_uploaded_file(file: &str) -> CmdResult { //! run_cmd!(/bin/rm -f /var/upload/$file) //! } //! ``` //! It is not the case in bash, which will always do variable substitution at first. //! //! ### Glob/Wildcard //! //! This library does not provide glob functions, to avoid silent errors and other surprises. //! You can use the [glob](https://github.com/rust-lang-nursery/glob) package instead. //! //! ### Thread Safety //! //! This library tries very hard to not set global states, so parallel `cargo test` can be executed just fine. //! However, the process APIs are inherently not thread-safe, as a result I sometimes need to set //! `RUST_TEST_THREADS=1` before running tests. pub use cmd_lib_macros::{export_cmd, run_cmd, run_fun, use_builtin_cmd, use_custom_cmd}; pub type FunResult = std::io::Result<String>; pub type CmdResult = std::io::Result<()>; pub use builtins::{builtin_echo, builtin_true}; pub use process::{export_cmd, set_debug, Cmd, CmdArgs, CmdEnvs, Cmds, FdOrFile, GroupCmds}; mod builtins; mod proc_var; mod process;