Common rust command-line macros and utilities, to write shell-script like tasks easily in rust programming language. Available at crates.io.
If you need to run some external commands in rust, the std::process::Command 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 or Piping is needed, you need to set up the parent and child IO handles manually, like this in the rust cookbook, which is often tedious and error prone.
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, they can usually be implemented as one line of rust macro with the help of this library, as in the examples/rust_cookbook.rs. Since they are rust code, you can always rewrite them in rust natively in the future, if necessary without spawning external commands.
To get a first impression, here is an example from examples/dd_test.rs:
run_cmd! (
info "Dropping caches at first";
sudo bash -c "echo 3 > /proc/sys/vm/drop_caches";
info "Running with thread_num: $thread_num, block_size: $block_size";
)?;
let cnt = DATA_SIZE / thread_num / block_size;
let now = Instant::now();
(0..thread_num).into_par_iter().for_each(|i| {
let off = cnt * i;
let bandwidth = run_fun!(
sudo bash -c "dd if=$file of=/dev/null bs=$block_size skip=$off count=$cnt 2>&1"
| awk r#"/copied/{print $(NF-1) " " $NF}"#
)
.unwrap_or_else(|_| cmd_die!("thread $i failed"));
info!("thread {i} bandwidth: {bandwidth}");
});
let total_bandwidth = Byte::from_bytes((DATA_SIZE / now.elapsed().as_secs()) as u128).get_appropriate_unit(true);
info!("Total bandwidth: {total_bandwidth}/s");Output will be like this:
➜ rust_cmd_lib git:(master) ✗ cargo run --example dd_test -- -b 4096 -f /dev/nvme0n1 -t 4
Finished dev [unoptimized + debuginfo] target(s) in 0.04s
Running `target/debug/examples/dd_test -b 4096 -f /dev/nvme0n1 -t 4`
[INFO ] Dropping caches at first
[INFO ] Running with thread_num: 4, block_size: 4096
[INFO ] thread 3 bandwidth: 317 MB/s
[INFO ] thread 1 bandwidth: 289 MB/s
[INFO ] thread 0 bandwidth: 281 MB/s
[INFO ] thread 2 bandwidth: 279 MB/s
[INFO ] Total bandwidth: 1.11 GiB/slet msg = "I love rust";
run_cmd!(echo $msg)?;
run_cmd!(echo "This is the message: $msg")?;
// pipe commands are also supported
let dir = "/var/log";
run_cmd!(du -ah $dir | sort -hr | head -n 10)?;
// or a group of commands
// if any command fails, just return Err(...)
let file = "/tmp/f";
let keyword = "rust";
run_cmd! {
cat ${file} | grep ${keyword};
echo "bad cmd" >&2;
ignore ls /nofile;
date;
ls oops;
cat oops;
}?;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);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. With tools like rust-analyzer, it can give you real-time feedback for broken
commands being used.
You can use cargo expand to check the generated code.
When passing parameters to run_cmd! and run_fun! macros, if they are not part to rust
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.
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)?;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,
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:
// 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)?;Notice here $awk_opts will be treated as single option passing to awk command.
If you want to use dynamic parameters, you can use $[] to access vector variable:
let gopts = vec![vec!["-l", "-a", "/"], vec!["-a", "/var"]];
for opts in gopts {
run_cmd!(ls $[opts])?;
}Right now piping and stdin, stdout, stderr redirection are supported. Most parts are the same as in bash scripts.
This library provides convenient macros and builtin commands for logging. All messages which are printed to stderr will be logged. It will also include the full running commands in the error result.
let dir: &str = "folder with spaces";
run_cmd!(mkdir /tmp/$dir; ls /tmp/$dir)?;
run_cmd!(mkdir /tmp/$dir; ls /tmp/$dir; rmdir /tmp/$dir)?;
// output:
// [INFO ] mkdir: cannot create directory ‘/tmp/folder with spaces’: File exists
// Error: Running ["mkdir" "/tmp/folder with spaces"] exited with error; status code: 1It is using rust log crate, and you can use your actual favorite logger implementation. Notice that if you don't provide any logger, it will use env_logger to print messages from process's stderr.
You can also mark your main() function with #[cmd_lib::main], which will log error from
main() by default. Like this:
[ERROR] FATAL: Running ["mkdir" "/tmp/folder with spaces"] exited with error; status code: 1cd: set process current directory.
run_cmd! (
cd /tmp;
ls | wc -l;
)?;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.
Ignore errors for command execution.
Print messages to stdout.
-n do not output the trailing newlinePrint messages to logging with different levels. You can also use the normal logging macros, if you don't need to do logging inside the command group.
run_cmd!(error "This is an error message")?;
run_cmd!(warn "This is a warning message")?;
run_cmd!(info "This is an information message")?;
// output:
// [ERROR] This is an error message
// [WARN ] This is a warning message
// [INFO ] This is an information messagespawn! macro executes the whole command as a child process, returning a handle to it. By
default, stdin, stdout and stderr are inherited from the parent. The process will run in the
background, so you can run other stuff concurrently. You can call wait() to wait
for the process to finish.
With spawn_with_output! you can get output by calling
wait_with_output(),
wait_with_all()
or even do stream
processing with wait_with_pipe().
There are also other useful APIs, and you can check the docs for more details.
let mut proc = spawn!(ping -c 10 192.168.0.1)?;
// do other stuff
// ...
proc.wait()?;
let mut proc = spawn_with_output!(/bin/cat file.txt | sed s/a/b/)?;
// do other stuff
// ...
let output = proc.wait_with_output()?;
spawn_with_output!(journalctl)?.wait_with_pipe(&mut |pipe| {
BufReader::new(pipe)
.lines()
.filter_map(|line| line.ok())
.filter(|line| line.find("usb").is_some())
.take(10)
.for_each(|line| println!("{}", line));
})?;Declare your function with the right signature, and register it with use_custom_cmd! macro:
fn my_cmd(env: &mut CmdEnv) -> CmdResult {
let args = env.get_args();
let (res, stdout, stderr) = spawn_with_output! {
orig_cmd $[args]
--long-option xxx
--another-option yyy
}?
.wait_with_all();
writeln!(env.stdout(), "{}", stdout)?;
writeln!(env.stderr(), "{}", stderr)?;
res
}
use_custom_cmd!(my_cmd);tls_init!to define thread local global variabletls_get!to get the valuetls_set!to set the value
tls_init!(DELAY, f64, 1.0);
const DELAY_FACTOR: f64 = 0.8;
tls_set!(DELAY, |d| *d *= DELAY_FACTOR);
let d = tls_get!(DELAY);
// check more examples in examples/tetris.rsYou can use std::env::var to fetch the environment variable key from the current process. It will report error if the environment variable is not present, and it also includes other checks to avoid silent failures.
To set environment variables, you can use std::env::set_var. There are also other related APIs in the std::env module.
To set environment variables for the command only, you can put the assignments before the command. Like this:
run_cmd!(FOO=100 /tmp/test_run_cmd_lib.sh)?;Using macros can actually avoid command injection, since we do parsing before variable substitution. For example, below code is fine even without any quotes:
fn cleanup_uploaded_file(file: &Path) -> CmdResult {
run_cmd!(/bin/rm -f /var/upload/$file)
}It is not the case in bash, which will always do variable substitution at first.
This library does not provide glob functions, to avoid silent errors and other surprises. You can use the glob package instead.
This library tries very hard to not set global states, so parallel cargo test can be executed just fine.
The only known APIs not supported in multi-thread environment are the
tls_init!/tls_get!/tls_set! macros, and you should only use them for thread local variables.
License: MIT OR Apache-2.0
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