mirror of
https://github.com/rust-lang-nursery/rust-cookbook
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Ludwig PACIFICI
Michał Budzyński
parent
85778f8586
commit
20c4e43e70
2 changed files with 68 additions and 0 deletions
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@ -9,6 +9,7 @@
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| [Generate random numbers with given distribution][ex-rand-dist] | [![rand-badge]][rand] | [![cat-science-badge]][cat-science] |
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| [Generate random values of a custom type][ex-rand-custom] | [![rand-badge]][rand] | [![cat-science-badge]][cat-science] |
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| [Run an external command and process stdout][ex-parse-subprocess-output] | [![regex-badge]][regex] | [![cat-os-badge]][cat-os] [![cat-text-processing-badge]][cat-text-processing] |
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| [Run piped external commands][ex-run-piped-external-commands] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
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| [Filter a log file by matching multiple regular expressions][ex-regex-filter-log] | [![regex-badge]][regex] | [![cat-text-processing-badge]][cat-text-processing]
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| [Declare lazily evaluated constant][ex-lazy-constant] | [![lazy_static-badge]][lazy_static] | [![cat-caching-badge]][cat-caching] [![cat-rust-patterns-badge]][cat-rust-patterns] |
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| [Maintain global mutable state][ex-global-mut-state] | [![lazy_static-badge]][lazy_static] | [![cat-rust-patterns-badge]][cat-rust-patterns] |
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@ -327,6 +328,70 @@ fn run() -> Result<()> {
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# quick_main!(run);
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```
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[ex-run-piped-external-commands]: #ex-run-piped-external-commands
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<a name="ex-run-piped-external-commands"></a>
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## Run piped external commands
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[![std-badge]][std] [![cat-os-badge]][cat-os]
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Shows up to the 10<sup>th</sup> biggest files and subdirectories in
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the current working directory. It is equivalant to run: `du -ah . |
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sort -hr | head -n 10`.
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It spawns Unix processes which are represented as [`Command`]s. In
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order to capture the output of a child process it is necessary to
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create a new [`Stdio::piped`] between parent and child.
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```rust,no_run
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# #[macro_use]
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# extern crate error_chain;
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#
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use std::process::{Command, Stdio};
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#
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# error_chain! {
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# foreign_links {
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# Io(std::io::Error);
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# Utf8(std::string::FromUtf8Error);
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# }
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# }
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fn run() -> Result<()> {
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let directory = std::env::current_dir()?;
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let du_output = Command::new("du")
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.arg("-ah")
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.arg(&directory)
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.stdout(Stdio::piped())
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.spawn()?
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.stdout
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.ok_or_else(|| "Could not capture `du` standard output.")?;
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let sort_output = Command::new("sort")
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.arg("-hr")
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.stdin(du_output)
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.stdout(Stdio::piped())
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.spawn()?
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.stdout
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.ok_or_else(|| "Could not capture `sort` standard output.")?;
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let head_output = Command::new("head")
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.args(&["-n", "10"])
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.stdin(sort_output)
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.stdout(Stdio::piped())
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.spawn()?
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.wait_with_output()?;
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println!(
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"Top 10 biggest files and directories in '{}':\n{}",
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directory.display(),
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String::from_utf8(head_output.stdout)?
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);
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Ok(())
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}
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#
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# quick_main!(run);
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```
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[ex-regex-filter-log]: #ex-regex-filter-log
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<a name="ex-regex-filter-log"></a>
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## Filter a log file by matching multiple regular expressions
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@ -904,6 +969,7 @@ fn main() {
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[`digest::Digest`]: https://docs.rs/ring/*/ring/digest/struct.Digest.html
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[rand-distributions]: https://doc.rust-lang.org/rand/rand/distributions/index.html
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[replacement string syntax]: https://docs.rs/regex/0.2.2/regex/struct.Regex.html#replacement-string-syntax
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[`Stdio::piped`]: https://doc.rust-lang.org/std/process/struct.Stdio.html
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<!-- Other Reference -->
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@ -27,6 +27,7 @@ community. It needs and welcomes help. For details see
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| [Generate random numbers with given distribution][ex-rand-dist] | [![rand-badge]][rand] | [![cat-science-badge]][cat-science] |
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| [Generate random values of a custom type][ex-rand-custom] | [![rand-badge]][rand] | [![cat-science-badge]][cat-science] |
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| [Run an external command and process stdout][ex-parse-subprocess-output] | [![regex-badge]][regex] | [![cat-os-badge]][cat-os] [![cat-text-processing-badge]][cat-text-processing] |
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| [Run piped external commands][ex-run-piped-external-commands] | [![std-badge]][std] | [![cat-os-badge]][cat-os] |
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| [Filter a log file by matching multiple regular expressions][ex-regex-filter-log] | [![regex-badge]][regex] | [![cat-text-processing-badge]][cat-text-processing]
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| [Declare lazily evaluated constant][ex-lazy-constant] | [![lazy_static-badge]][lazy_static] | [![cat-caching-badge]][cat-caching] [![cat-rust-patterns-badge]][cat-rust-patterns] |
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| [Maintain global mutable state][ex-global-mut-state] | [![lazy_static-badge]][lazy_static] | [![cat-rust-patterns-badge]][cat-rust-patterns] |
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@ -172,6 +173,7 @@ community. It needs and welcomes help. For details see
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[ex-invalid-csv]: encoding.html#ex-invalid-csv
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[ex-paginated-api]: net.html#ex-paginated-api
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[ex-parse-subprocess-output]: basics.html#ex-parse-subprocess-output
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[ex-run-piped-external-commands]: basics.html#ex-run-piped-external-commands
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[ex-verify-extract-email]: basics.html#ex-verify-extract-email
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[ex-percent-encode]: encoding.html#ex-percent-encode
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[ex-phone]: basics.html#ex-phone
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