Programming

Example of daemonizing in Rust use daemonize::Daemonize; fn main() { let daemonize = Daemonize::new() .pid_file("/tmp/my_daemon.pid") // Optional: Write PID to file .chown_pid_file(true) // Optional: Change ownership .working_directory("/tmp") // Optional: Set working directory .privileged_action(|| "Executed before drop privileges"); match daemonize.start() { Ok(_) => { // Daemon logic goes here println!("Daemon started successfully!"); loop { // Do daemon work std::thread::sleep(std::time::Duration::from_secs(5)); } }, Err(e) => eprintln!("Error, {}", e), } }

Getting Environment variables In Rust, we use std::env use std::env; fn main() { let x = env::vars(); for (a, b) in x { println!("{:?} {:?}", a, b) } } "ALTERNATE_EDITOR" "emacsclient -c " "BASH_FUNC_pathappend%%" "() { pathremove \"${1}\" \"${2}\";\n local PATHVARIABLE=${2:-PATH};\n export \"$PATHVARIABLE\"=\"${!PATHVARIABLE:+${!PATHVARIABLE}:}$1\"\n}" "BASH_FUNC_pathprepend%%" "() { pathremove \"${1}\" \"${2}\";\n local PATHVARIABLE=${2:-PATH};\n export \"$PATHVARIABLE\"=\"$1${!PATHVARIABLE:+:${!PATHVARIABLE}}\"\n}" "BASH_FUNC_pathremove%%" "() { local IFS=':';\n local NEWPATH;\n local DIR;\n local PATHVARIABLE=${2:-PATH};\n for DIR in ${!PATHVARIABLE};\n do\n if [ \"${DIR}\" != \"${1}\" ]; then\n NEWPATH=${NEWPATH:+$NEWPATH:}$DIR;\n fi;\n done;\n export \"$PATHVARIABLE\"=\"${NEWPATH}\"\n}" "BROWSER" "firefox" "CARGO" "/home/alexforsale/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/bin/cargo" "CARGO_HOME" "/home/alexforsale/.cargo" "CARGO_MANIFEST_DIR" "/tmp/babel-5iTIx3/cargoDOdDFj" "CARGO_MANIFEST_PATH" "/tmp/babel-5iTIx3/cargoDOdDFj/Cargo.toml" "CARGO_PKG_AUTHORS" "" "CARGO_PKG_DESCRIPTION" "" "CARGO_PKG_HOMEPAGE" "" "CARGO_PKG_LICENSE" "" "CARGO_PKG_LICENSE_FILE" "" "CARGO_PKG_NAME" "cargoDOdDFj" "CARGO_PKG_README" "" "CARGO_PKG_REPOSITORY" "" "CARGO_PKG_RUST_VERSION" "" "CARGO_PKG_VERSION" "0.1.0" "CARGO_PKG_VERSION_MAJOR" "0" "CARGO_PKG_VERSION_MINOR" "1" "CARGO_PKG_VERSION_PATCH" "0" "CARGO_PKG_VERSION_PRE" "" "CLICOLOR" "1" "DBUS_SESSION_BUS_ADDRESS" "unix:path=/run/user/1000/bus" "DEBUGINFOD_URLS" "https://debuginfod.archlinux.org " "DESKTOP_SESSION" "i3" "DISPLAY" ":0" "DISTRO" "arch" "DISTROVER" "rolling" "EDITOR" "emacsclient -t " "FILE" "emacsclient -c -e (dired-jump)" "GOPATH" "/home/alexforsale/.local" "GPG_TTY" "/dev/tty1" "GTK2_RC_FILES" "/home/alexforsale/.config/gtk-2.0/gtkrc" "GTK_MODULES" "canberra-gtk-module" "GTK_RC_FILES" "/home/alexforsale/.config/gtk-1.0/gtkrc" "GTK_THEME" "Breeze-Dark" "HG" "/usr/bin/hg" "HISTFILE" "/home/alexforsale/.local/share/bash/bash_history" "HOME" "/home/alexforsale" "I3SOCK" "/run/user/1000/i3/ipc-socket.2313" "LANG" "en_US.UTF-8" "LD_LIBRARY_PATH" "/tmp/babel-5iTIx3/cargoDOdDFj/target/debug/deps:/tmp/babel-5iTIx3/cargoDOdDFj/target/debug:/home/alexforsale/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib:/home/alexforsale/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib" "LOGNAME" "alexforsale" "LS_COLORS" "rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=00:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.7z=01;31:*.ace=01;31:*.alz=01;31:*.apk=01;31:*.arc=01;31:*.arj=01;31:*.bz=01;31:*.bz2=01;31:*.cab=01;31:*.cpio=01;31:*.crate=01;31:*.deb=01;31:*.drpm=01;31:*.dwm=01;31:*.dz=01;31:*.ear=01;31:*.egg=01;31:*.esd=01;31:*.gz=01;31:*.jar=01;31:*.lha=01;31:*.lrz=01;31:*.lz=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.lzo=01;31:*.pyz=01;31:*.rar=01;31:*.rpm=01;31:*.rz=01;31:*.sar=01;31:*.swm=01;31:*.t7z=01;31:*.tar=01;31:*.taz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tgz=01;31:*.tlz=01;31:*.txz=01;31:*.tz=01;31:*.tzo=01;31:*.tzst=01;31:*.udeb=01;31:*.war=01;31:*.whl=01;31:*.wim=01;31:*.xz=01;31:*.z=01;31:*.zip=01;31:*.zoo=01;31:*.zst=01;31:*.avif=01;35:*.jpg=01;35:*.jpeg=01;35:*.jxl=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.webp=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:*~=00;90:*#=00;90:*.bak=00;90:*.crdownload=00;90:*.dpkg-dist=00;90:*.dpkg-new=00;90:*.dpkg-old=00;90:*.dpkg-tmp=00;90:*.old=00;90:*.orig=00;90:*.part=00;90:*.rej=00;90:*.rpmnew=00;90:*.rpmorig=00;90:*.rpmsave=00;90:*.swp=00;90:*.tmp=00;90:*.ucf-dist=00;90:*.ucf-new=00;90:*.ucf-old=00;90:" "MAIL" "/var/spool/mail/alexforsale" "MAIL_APP" "thunderbird" "MM_CHARSET" "en_US.UTF-8" "MONITOR1" "DP-1" "MOTD_SHOWN" "pam" "PATH" "/home/alexforsale/.local/perl5/bin:/home/alexforsale/.ghcup/bin:/home/alexforsale/.cargo/bin:/home/alexforsale/.cabal/bin:/home/alexforsale/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/usr/lib/rustup/bin" "PERL5LIB" "/home/alexforsale/.local/perl5/lib/perl5" "PERL_LOCAL_LIB_ROOT" "/home/alexforsale/.local/perl5" "PERL_MB_OPT" "--install_base \"/home/alexforsale/.local/perl5\"" "PERL_MM_OPT" "INSTALL_BASE=/home/alexforsale/.local/perl5" "PWD" "/tmp/babel-5iTIx3/cargoDOdDFj" "QT_XCB_GL_INTEGRATION" "none" "RUSTUP_HOME" "/home/alexforsale/.rustup" "RUSTUP_TOOLCHAIN" "stable-x86_64-unknown-linux-gnu" "RUST_BACKTRACE" "0" "RUST_RECURSION_COUNT" "1" "SCREENDIR" "/home/alexforsale/.config/screen" "SCREENRC" "/home/alexforsale/.config/screen/config" "SHELL" "/usr/bin/bash" "SHLVL" "2" "SSH_AGENT_PID" "2186" "SSH_ASKPASS" "ssh-askpass" "SSH_AUTH_SOCK" "/tmp/ssh-XXXXXXZtMjDO/agent.2185" "SSL_CERT_DIR" "/etc/ssl/certs" "SSL_CERT_FILE" "/etc/ssl/cert.pem" "SUDO_ASKPASS" "/home/alexforsale/.local/bin/ssh-askpass" "TERM" "ansi" "TERMINAL" "alacritty" "USER" "alexforsale" "VISUAL" "emacsclient -c " "WINDOWPATH" "1" "XAUTHORITY" "/home/alexforsale/.Xauthority" "XCURSOR_PATH" ":/usr/share/icons:/home/alexforsale/.local/share/icons" "XCURSOR_SIZE" "24" "XCURSOR_THEME" "Bibata-Modern-Classic" "XDG_CACHE_HOME" "/home/alexforsale/.cache" "XDG_CONFIG_HOME" "/home/alexforsale/.config" "XDG_DATA_DIRS" "/usr/share:/usr/local/share" "XDG_DATA_HOME" "/home/alexforsale/.local/share" "XDG_DESKTOP_DIR" "/home/alexforsale/Desktop" "XDG_DOCUMENTS_DIR" "/home/alexforsale/Documents" "XDG_DOWNLOAD_DIR" "/home/alexforsale/Downloads" "XDG_MUSIC_DIR" "/home/alexforsale/Music" "XDG_PICTURES_DIR" "/home/alexforsale/Pictures" "XDG_PUBLICSHARE_DIR" "/home/alexforsale/Public" "XDG_RUNTIME_DIR" "/run/user/1000" "XDG_SEAT" "seat0" "XDG_SESSION_CLASS" "user" "XDG_SESSION_ID" "1" "XDG_SESSION_TYPE" "tty" "XDG_TEMPLATES_DIR" "/home/alexforsale/Templates" "XDG_VIDEOS_DIR" "/home/alexforsale/Videos" "XDG_VTNR" "1" "_" "/usr/bin/emacs" "npm_config_prefix" "/home/alexforsale/.local" Specific Variable std::env::var returns a Result<String, VarError>. ...

use std::process::Command; fn main() { let mut list_dir = Command::new("ls"); list_dir.status().expect("process failed to execute"); println!(); } Cargo.lock Cargo.toml src target

fn fib(x: i32) -> i32 { match x { 0 => 0, 1 => 1, _ => fib(x -1) + fib(x -2), } } fn main() { for a in 0..=10 { println!("fib {} is: {}", a, fib(a)) } } fib 0 is: 0 fib 1 is: 1 fib 2 is: 1 fib 3 is: 2 fib 4 is: 3 fib 5 is: 5 fib 6 is: 8 fib 7 is: 13 fib 8 is: 21 fib 9 is: 34 fib 10 is: 55 use std::collections::HashMap; fn memoized_fib(n: u64, memo: &mut HashMap<u64, u64>) -> u64 { if memo.contains_key(&n) { return *memo.get(&n).unwrap(); } let result = match n { 0 => 0, 1 => 1, _ => memoized_fib(n - 1, memo) + memoized_fib(n - 2, memo), }; memo.insert(n, result); result } fn main() { let mut memo: HashMap<u64, u64> = HashMap::new(); for x in 0..=20 { println!("fib ({}): {}", x, memoized_fib(x, &mut memo)); } } fib (0): 0 fib (1): 1 fib (2): 1 fib (3): 2 fib (4): 3 fib (5): 5 fib (6): 8 fib (7): 13 fib (8): 21 fib (9): 34 fib (10): 55 fib (11): 89 fib (12): 144 fib (13): 233 fib (14): 377 fib (15): 610 fib (16): 987 fib (17): 1597 fib (18): 2584 fib (19): 4181 fib (20): 6765

Cargo Cargo is the Rust package manager. Cargo downloads your Rust package’s dependencies, compiles your packages, makes distributable packages, and uploads them to crates.io, the Rust community’s package registry. You can contribute to this book on GitHub.

Common Collection Rust’s standard library includes a number of very useful data structures called collections. Most other data types represent one specific value, but collections can contain multiple values. Unlike the built-in array and tuple types, the data that these collections point to is stored on the heap, which means the amount of data does not need to be known at compile time and can grow or shrink as the program runs. Each kind of collection has different capabilities and costs, and choosing an appropriate one for your current situation is a skill you’ll develop over time. ...

Comments All programmers strive to make their code easy to understand, but sometimes extra explanation is warranted. In these cases, programmers leave comments in their source code that the compiler will ignore but people reading the source code may find useful. // hello, world In Rust, the idiomatic comment style starts a comment with two slashes, and the comment continues until the end of the line. For comments that extend beyond a single line, you’ll need to include // on each line, like this: ...

Control Flow The ability to run some code depending on whether a condition is true and to run some code repeatedly while a condition is true are basic building blocks in most programming languages. The most common constructs that let you control the flow of execution of Rust code are if expressions and loops.

Defining Enum Where structs give you a way of grouping together related fields and data, like a Rectangle with its width and height, enums give you a way of saying a value is one of a possible set of values. For example, we may want to say that Rectangle is one of a set of possible shapes that also includes Circle and Triangle. To do this, Rust allows us to encode these possibilities as an enum. ...

Functions Functions are prevalent in Rust code. You’ve already seen one of the most important functions in the language: the main function, which is the entry point of many programs. You’ve also seen the fn keyword, which allows you to declare new functions. Rust code uses snake case as the conventional style for function and variable names, in which all letters are lowercase and underscores separate words. Here’s a program that contains an example function definition: ...