Programming Tutorials and Coding Guides - Page 3

Compare integers in Bash with -eq, -gt, [ ], [[ ]], and (( )); handle leading zeros, negative values, untrusted input, and decimal checks with bc or awk.

Check whether a file or directory exists in Bash with -e, -f, and -d, including missing paths, symlinks, permissions, and practical shell script examples.

Compare strings in Bash with =, ==, !=, -z and -n. Learn empty vs unset values, substring and glob matching, case-insensitive checks, and lexical ordering.

Learn when to use Bash [ ], [[ ]], and (( )) for tests: POSIX test syntax, Bash conditionals, pattern and regex matching, numeric comparisons, and common failure examples.

Learn how to use the Bash case statement with practical examples, match multiple values and wildcard patterns, add a default case, and compare case with if/elif.

Learn Bash if, elif, and else syntax with examples for variables, multiple conditions, command exit status, nested if statements, and common errors.

Learn Bash arithmetic with $(( )) and (( )), including operators, integer division, counters, number bases, and floating-point calculations with awk and bc.

Learn how Bash exit codes work, check the last status with $?, use exit, understand codes 0, 1, 126 and 127, and handle pipeline failures with PIPESTATUS and pipefail.

Concatenate strings in Bash with adjacent expansions, ${var} brace boundaries, += append, separators, printf -v formatting, and safe patterns for command output and loops.

Get the Bash script name, absolute path, and directory with $0, BASH_SOURCE, dirname, cd+pwd, and GNU readlink -f — including sourced files and symlinks.

Compare Bash echo and printf for newlines, prompts, columns, and portable scripts: echo -n, echo -e pitfalls, printf format strings, printf -v, stderr output, and safe printing of variable content.

Learn Bash script arguments with $1, $#, $@, $*, shift, and ${10}. See how quoting preserves filenames with spaces, validate argument counts, and forward args safely to cp and other commands.

Learn the Bash read builtin for interactive input: read into variables, use -r by default, prompt with -p, split fields with IFS, hide passwords with -s, time out with -t, and read arrays with -a.

Learn how Bash environment variables work with export, env, and printenv, how child processes inherit them, and how to set, list, unexport, and unset variables.

Learn when Bash reads .bashrc, .bash_profile, and .profile on login and non-login shells, how SSH and cron differ, what BASH_ENV does, and where to put PATH, aliases, and exports.

Compare Bash single vs double quotes with tested examples. Learn variable expansion, escaping quotes, $'...' syntax, globbing, filenames with spaces, and safe variable quoting.

Learn how to create, assign, expand, quote, unset, and protect Bash variables with declare and readonly, plus how unset differs from empty and when to use ${var}.

Learn Bash comment syntax with #, inline comments, quoted hash characters, multiline comments, heredoc workarounds, and how shebang lines differ from ordinary comments.

Compare Bash vs sh with tested examples. Learn POSIX portability, Bash-only syntax, what /bin/sh runs, and when to use #!/bin/bash or #!/bin/sh.

Learn what a Bash shebang does, how #!/bin/bash differs from #!/usr/bin/env bash, when the shebang is ignored, and which one to use in shell scripts.

Learn how to write a .bat file on Windows, from echo and variables to arguments, loops, delayed expansion, exit codes, and a complete logging backup script you can adapt.

Learn how to rename a file in Python with pathlib Path.rename(), Path.replace(), os.rename(), os.replace(), and shutil.move(), including extension changes, batch renames, overwrite rules, and cross-filesystem moves.

Learn Go time formatting and parsing with the reference date 2006-01-02, RFC3339, DateOnly, time.Format, time.Parse, ParseInLocation, and timezone layouts.

Learn Go's time package with examples for time.Now, UTC, Duration, Add and Sub, Unix timestamps, time zones, Format, Parse, Sleep, Timer, and Ticker.

Convert a Go string to uint8 using strconv.ParseUint, validate the 0–255 range, and learn the difference between parsing numeric text and reading a string byte.

Learn how to use a Go struct defined in another file, import an exported struct from another package, and fix undefined errors caused by go run main.go.

Convert int to int64 and int64 to int in Go, understand 32-bit vs 64-bit int sizes, check values before narrowing, and choose the correct integer type.

Learn how to kill a process by PID in Go, stop exec.Command children, use Process.Signal vs Kill, handle timeouts with CommandContext, and avoid orphan processes.

Learn how io.ReadCloser combines Reader and Closer in Go, how to close HTTP response bodies, wrap readers with io.NopCloser, and read content with io.ReadAll.

Fix Go "package is not in GOROOT", "cannot find package", and missing module errors by checking go.mod, import paths, workspaces, dependencies, and GOPATH mode.