Add bash rosetta notes

notes/shell/bash_rosetta.md

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+# Using shell in other languages
+Bash is incredibly concise at allowing programs to interact on a basic level,
+however it severely lacks control flow and sensible data structures, which make
+it a bad choice for logic-heavy scripting
+
+In these cases we can attempt to recreate the high-level control bash has over
+programs in other languages. All languages are able to call programs exactly
+like bash, though almost all of them are much more verbose
+
+The examples below use translate line of bash
+
+```bash
+swaymsg -t get_tree | jq '.nodes[1].nodes[].representation' | tr -d '\"'
+```
+
+## Python
+A great and portable choice for easy scripting
+
+```python
+from subprocess import Popen, PIPE
+
+p1 = Popen(["swaymsg", "-t", "get_tree"], stdout=PIPE);
+p2 = Popen(["jq", ".nodes[1].nodes[].representation"],
+        stdin=PIPE,
+        stdout=PIPE);
+p3 = Popen(["tr", "-d", '"'), stdin=PIPE, stdout=PIPE)
+
+p1_stdout, _ = p1.communicate(timeout=1)
+p2_stdout, _ = p2.communicate(p1_stdout, timeout=1)
+p3_stdout, _ = p3.communicate(p2_stdout, timeout=1)
+print(str(p3_stdout))
+```
+
+Shell-like strings can easily be split into the args lists required by Popen
+
+```python
+from shlex import split as shsplit
+# ...
+p3 = Popen(shsplit("tr -d '\"'"), stdin=PIPE, stdout=PIPE)
+# ...
+```
+
+Do not use pipes even in the shsplit strings. Pipes must be manually managed,
+unless the `shell=True` parameter is passed to Popen. However, that essentially
+completely gives up control over the subprocess, so it's highly not recommend
+
+## Rust
+Rust is very fast, though not very portable. Portable binaries can be made by
+compiling with a musl libc target. That way everything will be statically linked
+into the binary, which typically makes it work across all Linux systems
+
+```bash
+cargo build --release --target=x86_64-unknown-linux-musl
+```
+
+Rust is extremely verbose, though allows for very fine error handling. The below
+uses unwrap mostly
+
+```rust
+use std::io::{self, BufRead, BufReader};
+use std::process::{Command, Stdio, ChildStdout};
+
+fn get_tree() -> io::Result<ChildStdout> {
+    let swaymsg = Command::new("swaymsg")
+        .arg("-t")
+        .arg("get_tree")
+        .stdout(Stdio::piped())
+        .spawn()?;
+
+    let jq = Command::new("jq")
+        .arg(".nodes[1].nodes[].representation")
+        .stdin(swaymsg.stdout.unwrap())
+        .stdout(Stdio::piped())
+        .spawn()
+        .expect("`jq` binary is not available");
+
+    let tr = Command::new("tr")
+        .arg("-d")
+        .arg("\"")
+        .stdin(jq.stdout.unwrap())
+        .stdout(Stdio::piped())
+        .spawn()?;
+
+    Ok(tr.stdout.unwrap())
+}
+```